Assignment of the slowly exchanging substrate water of nature's water-splitting cofactor.

Identifying the two substrate water sites of nature's water-splitting cofactor (Mn4CaO5 cluster) provides important information toward resolving the mechanism of O-O bond formation in Photosystem II (PSII). To this end, we have performed parallel substrate water exchange experiments in the S1 state of native Ca-PSII and biosynthetically substituted Sr-PSII employing Time-Resolved Membrane Inlet Mass Spectrometry (TR-MIMS) and a Time-Resolved 17O-Electron-electron Double resonance detected NMR (TR-17O-EDNMR) approach. TR-MIMS resolves the kinetics for incorporation of the oxygen-isotope label into the substrate sites after addition of H218O to the medium, while the magnetic resonance technique allows, in principle, the characterization of all exchangeable oxygen ligands of the Mn4CaO5 cofactor after mixing with H217O. This unique combination shows i) that the central oxygen bridge (O5) of Ca-PSII core complexes isolated from Thermosynechococcus vestitus has, within experimental conditions, the same rate of exchange as the slowly exchanging substrate water (WS) in the TR-MIMS experiments and ii) that the exchange rates of O5 and WS are both enhanced by Ca2+→Sr2+ substitution in a similar manner. In the context of previous TR-MIMS results, this shows that only O5 fulfills all criteria for being WS. This strongly restricts options for the mechanism of water oxidation.

Toward a molecular understanding of the surface composition of atmospherically relevant organic particles.

Many mass spectrometry methods using various ionization sources provide bulk composition of airborne particles, but little is known about the surface species that play a major role in determining their physicochemical properties that impact air quality, climate, and health. The present work shows that the composition of surface layers of atmospherically relevant submicron organic particles can be probed without the use of an external ionization source. Solid dicarboxylic acid particles are used as models, with glutaric acid being the most efficient at generating ions. Coating with small diacids or products from α-pinene ozonolysis demonstrates that ions are ejected from the surface, providing surface molecular characterization of organic particles on the fly. This unique approach provides a path forward for elucidating the role of the surface in determining chemical and physical properties of particles, including heterogeneous reactions, particle growth, water uptake, and interactions with biological systems.

On the simulation and interpretation of substrate-water exchange experiments in photosynthetic water oxidation.

Water oxidation by photosystem II (PSII) sustains most life on Earth, but the molecular mechanism of this unique process remains controversial. The ongoing identification of the binding sites and modes of the two water-derived substrate oxygens ('substrate waters') in the various intermediates (Si states, i = 0, 1, 2, 3, 4) that the water-splitting tetra-manganese calcium penta-oxygen (Mn4CaO5) cluster attains during the reaction cycle provides central information towards resolving the unique chemistry of biological water oxidation. Mass spectrometric measurements of single- and double-labeled dioxygen species after various incubation times of PSII with H218O provide insight into the substrate binding modes and sites via determination of exchange rates. Such experiments have revealed that the two substrate waters exchange with different rates that vary independently with the Si state and are hence referred to as the fast (Wf) and the slow (WS) substrate waters. New insight for the molecular interpretation of these rates arises from our recent finding that in the S2 state, under special experimental conditions, two different rates of WS exchange are observed that appear to correlate with the high spin and low spin conformations of the Mn4CaO5 cluster. Here, we reexamine and unite various proposed methods for extracting and assigning rate constants from this recent data set. The analysis results in a molecular model for substrate-water binding and exchange that reconciles the expected non-exchangeability of the central oxo bridge O5 when located between two Mn(IV) ions with the experimental and theoretical assignment of O5 as WS in all S states. The analysis also excludes other published proposals for explaining the water exchange kinetics.

Numerical model study on stability of a micro-tidal inlet at Muttukadu along the east coast of Bay of Bengal.

The complexity of micro-tidal inlets arises from the combined action of littoral drift and tidal range on their stability. Consequently, understanding and evaluating their stability poses a significant challenge. This study aims to shed some insight on the assessment of inlet stability by employing Delft 3D model. The stability of the inlet between the ocean and estuary relies on the balance between the longshore transport rate and the spring tidal prism. Disrupting this equilibrium results in the closure of the inlets. The movement of sediments in the surf zone is primarily driven by longshore velocity, which acts as the driving force for littoral drift, which is estimated using Delft 3D wave model. The longshore transport rate is estimated by employing empirical relationships and numerical codes based on the obtained driving force. Subsequently, the stability of the inlet is assessed based on these estimations. The spring tidal prism refers to the discharge of water flowing into the ocean from inlets and estuaries. Flow velocity is determined using Delft 3D flow model. The input data for nearshore circulation resulting from waves and currents is primarily collected through field measurements and data collected from Indian National Centre for Ocean Information Services (INCOIS). For the current study, Muttukadu (12°47'13″N, 80°15'01″E) inlet, Kovalam along the East Coast of the Indian Peninsula is investigated by assessing its seasonal variations. This study contributes to the management of marine biological ecology, the expansion of small-scale artisanal fishing, the promotion of water sports-related tourism, the advancement of fishing harbor development, and the execution of coastal engineering projects.

Staged Ventricular Septation of the Double-Inlet Ventricle: How-I-Do-It.

Ventricular septation of the double-inlet ventricle is a largely abandoned operation due to poor historical outcomes. However, there has been renewed interest in septation as an alternative to Fontan palliation given its long-term sequelae. As one of the few centers to revisit septation in the early 1990s, our institution has long-term data on a series of patients with a double-inlet ventricle who underwent biventricular repair. This manuscript is a summary of our approach to staged septation of the double-inlet ventricle, with a focus on patient selection criteria, surgical techniques, perioperative considerations on timing of interventions, and long-term results. We believe that septation of the double-inlet ventricle should be reconsidered in patients with suitable anatomy in light of the known complications of Fontan palliation.

Imaging of Double Inlet Left Ventricle.

Double inlet left ventricle (DILV) is a form of single ventricle heart disease where both atrioventricular valves enter a single left ventricle. Surgical intervention may be needed in the neonatal period secondary to systemic outflow tract obstruction or less commonly pulmonary obstruction. Two-dimensional echocardiography can adequately assess newborn anatomy and define the need for surgery. Beyond the newborn period, there is a renewed interest in septation of DILV using intracardiac baffles in a staged approach. Cross sectional imaging can aid in surgical planning. This article will review common anatomic features of DILV and imaging considerations for both single ventricle palliation and DILV septation.

Usefulness of the preoperative thoracic inlet angle in comparison to the T1 slope for predicting cervical kyphosis after laminoplasty.

PURPOSE: Thoracic inlet angle (TIA) is a sagittal radiographic parameter with a constant value regardless of posture and is significantly correlated with the sagittal balance of the cervical spine. However, the practical use of TIA has not been studied. This study aimed to investigate the usefulness of the preoperative TIA for predicting the development of kyphotic deformity after cervical laminoplasty in comparison to the preoperative T1 slope (T1S). METHODS: A total of 98 patients who underwent cervical laminoplasty without preoperative kyphotic alignment were included (mean age, 73.7 years; 41.8% female). Radiography was evaluated before surgery and at the 2-year follow-up examination. The cervical sagittal parameters were measured on standing radiographs, and the TIA was measured on T2-weighted MRI in a supine position. Cervical alignment with a C2-C7 angle of ≥ 0° was defined as lordosis, and that with an angle of < 0° was defined as kyphosis. RESULTS: Postoperative kyphosis occurred in 11 patients (11.2%). Preoperatively, the kyphosis group showed significantly lower values in the T1S (23.5° vs. 30.3°, p = 0.034) and TIA (76.1° vs. 81.8°, p = 0.042). We performed ROC curve analysis to clarify the impact of the preoperative TIA and T1S on kyphotic deformity after laminoplasty. The optimal cutoff angles for TIA and T1S were 68° and 19°, respectively, with similar diagnostic accuracy. CONCLUSION: This study demonstrated the clinical utility of the preoperative TIA for predicting the risk of postoperative kyphotic deformity after cervical laminoplasty. These findings suggest the importance of the preoperative assessment of thoracic inlet alignment in cervical spine surgery.

Ventricular Septal Defects: Molecular Pathways and Animal Models.

Ventricular septation is a complex process which involves the major genes of cardiac development, acting on myocardial cells from first and second heart fields, and on mesenchymal cells from endocardial cushions. These genes, coding for transcription factors, interact with each other, and their differential expression conditions the severity of the phenotype. In this chapter, we will describe the formation of the ventricular septum in the normal heart, as well as the molecular mechanisms leading to the four main anatomic types of ventricular septal defects: outlet, inlet, muscular, and central perimembranous, resulting from failure of development of the different parts of the ventricular septum. Experiments on animal models, particularly transgenic mouse lines, have helped us to decipher the molecular determinants of ventricular septation. However, a precise description of the anatomic phenotypes found in these models is mandatory to achieve a better comprehension of the complex mechanisms responsible for the various types of VSDs.

Clinical Presentation and Therapy of Ventricular Septal Defect.

Ventricular septal defects (VSDs) occur in 1.5-3.5 of 1000 live births and constitutes 20 % of congenital cardiac defects. There is no gender predominance.

Ventricular Septation of the Double-Inlet Ventricle: Over Three Decades of Follow-Up.

There is renewed interest in septation of the double-inlet ventricle as an alternative to Fontan palliation. We examined our septation experience with over 30 years of follow-up. We retrospectively reviewed patients with double-inlet ventricle from 1990 to 2011. Patients with two adequate atrioventricular valves, a volume-overloaded ventricle, and no significant subaortic obstruction were septation candidates. Of 98 double-inlet ventricle patients, 9 (9.2%) underwent attempted septation via a one-stage (n = 2, 22.2%) or two-stage (n = 7, 77.8%) approach. Ages at primary septation were 7.5 and 20.2 months. In the staged group, median age at the first and second stage was 8.3 months [range 4.1-14.7] and 22.4 months [range 11.4-195.7], respectively. There were no operative mortalities. Median follow-up was 18.8 years [range 0.4-32.9] and 30-year transplant-free survival was 77.8% ± 13.9%. Both single stage patients are alive and in sinus rhythm; 1 underwent bilateral outflow tract obstruction repair 27 years later. Of 7 patients planned for two-stage septation, there was 1 interval mortality and 1 deferred the second stage. Five patients underwent the second stage; 1 required early reintervention for a residual neo-septal defect and 1 underwent right atrioventricular valve replacement 28 years later. Three patients required a pacemaker preoperatively (n = 1) or after partial septation (n = 2). At latest follow-up, 7 patients have normal biventricular function and no significant valvulopathy. All remain NYHA functional class I. Select double-inlet ventricles may be septated with excellent long-term outcomes. Reconsideration of this strategy is warranted to avoid the sequelae of Fontan circulation.

Using unsupervised learning to classify inlet water for more stable design of water reuse in industrial parks.

The water reuse facilities of industrial parks face the challenge of managing a growing variety of wastewater sources as their inlet water. Typically, this clustering outcome is designed by engineers with extensive expertise. This paper presents an innovative application of unsupervised learning methods to classify inlet water in Chinese water reuse stations, aiming to reduce reliance on engineer experience. The concept of 'water quality distance' was incorporated into three unsupervised learning clustering algorithms (K-means, DBSCAN, and AGNES), which were validated through six case studies. Of the six cases, three were employed to illustrate the feasibility of the unsupervised learning clustering algorithm. The results indicated that the clustering algorithm exhibited greater stability and excellence compared to both artificial clustering and ChatGPT-based clustering. The remaining three cases were utilized to showcase the reliability of the three clustering algorithms. The findings revealed that the AGNES algorithm demonstrated superior potential application ability. The average purity in six cases of K-means, DBSCAN, and AGNES were 0.947, 0.852, and 0.955, respectively.

Characterizing compensatory mechanisms in the absence of photoprotective qE in Chlamydomonas reinhardtii.

Rapid fluctuations in the quantity and quality of natural light expose photosynthetic organisms to conditions when the capacity to utilize absorbed quanta is insufficient. These conditions can result in the production of reactive oxygen species and photooxidative damage. Non-photochemical quenching (NPQ) and alternative electron transport are the two most prominent mechanisms which synergistically function to minimize the overreduction of photosystems. In the green alga Chlamydomonas reinhardtii, the stress-related light-harvesting complex (LHCSR) is a required component for the rapid induction and relaxation of NPQ in the light-harvesting antenna. Here, we use simultaneous chlorophyll fluorescence and oxygen exchange measurements to characterize the acclimation of the Chlamydomonas LHCSR-less mutant (npq4lhcsr1) to saturating light conditions. We demonstrate that, in the absence of NPQ, Chlamydomonas does not acclimate to sinusoidal light through increased light-dependent oxygen consumption. We also show that the npq4lhcsr1 mutant has an increased sink capacity downstream of PSI and this energy flow is likely facilitated by cyclic electron transport. Furthermore, we show that the timing of additions of mitochondrial inhibitors has a major influence on plastid/mitochondrial coupling experiments.

Distribution characteristics of microplastics in storm-drain inlet sediments affected by the types of urban functional areas, economic and demographic conditions in southern Beijing.

A storm-drain inlet is an important link in the transport of microplastic pollutants in urban rainwater runoff. In three functional districts (agricultural, commercial, and residential) from Beijing South 2nd Ring Road to South 6th Ring Road, microplastics in storm-drain inlet sediments were analyzed for abundance and characteristics. The abundance of microplastics in the collected samples ranged from 1121 ± 247 items kg-1 to 7393 ± 491 items kg-1. Among the sample areas, the commercial area had the greatest abundance (11094 items kg-1), while the agricultural area had the lowest (833 items kg-1). The microplastics in the samples were mainly fragments, accounting for 50.4%. Microplastics of less than 1 mm accounted for 74.8%. The color of microplastics was diverse, with colored MPs accounting for 26% and transparent ones for 47.8%. Most of the polymers detected were PET, PS, and PP, which are the most commonly used polymers. Overall, the results provide baseline data on microplastic pollution and its associated risks, in addition to guidelines for controlling runoff pollution.

Esophageal Inlet Patch: Association with Barrett's Esophagus.

BACKGROUND: Esophageal inlet patch (IP) with heterotopic gastric mucosa is an incidental finding on esophagogastroduodenoscopy (EGD). Although IP is thought to be embryologic in nature, IP has been associated with Barrett's esophagus (BE). AIMS: The aim of this study was to compare prevalence, symptoms, demographic factors, and esophageal testing in patients with IP and BE. METHODS: We retrospectively analyzed endoscopic findings of EGDs, high-resolution esophageal manometry and esophageal pH impedance studies from January 2010 to January 2021 at a single academic medical center. Patients were grouped by presence or absence of IP and BE. RESULTS: Of 27,498 patients evaluated, 1.3% had endoscopic evidence of IP and 4.9% had BE. Of 362 patients with IP, 17.1% had BE; of 1356 patients with BE, 4.6% had IP. Both IP and BE patients presented primarily with heartburn and/or regurgitation. Patients with BE and/or IP were older and had higher BMI than those without (p < 0.001). Mean lower esophageal sphincter pressure was lower and mean acid exposure time (AET) was higher in patients with IP and/or BE than those without (p < 0.05). CONCLUSIONS: Our study reports an IP prevalence of 1.3%, with 17.1% patients having concomitant BE; and a BE prevalence of 4.9%, with 4.6% also having IP. Patients with IP alone presented with similar symptoms to patients with concomitant BE. Esophageal function testing showed that patients with either IP or BE had decreased LES pressures and increased esophageal AET. During endoscopy, patients found to have one of these findings should be carefully examined for the other.

Argon Plasma Coagulation of Gastric Inlet Patches of the Cervical Esophagus Relieves Vocal and Respiratory Symptoms in Selected Patients.

OBJECTIVES: Argon plasma coagulation (APC) of gastric inlet patches of the cervical esophagus (GIP) has been shown to relieve the globus sensation. This study aimed to investigate the long-term effects of APC therapy on a variety of laryngopharyngeal symptoms. METHODS: Patients with laryngopharyngeal symptoms who had undergone endoscopic GIP eradication via APC therapy were eligible for a retrospective observational cohort study. Symptom relief was assessed by a five-grade scale during a structured interview. Statistical analysis included ANOVA, the chi-squared and t-test. RESULTS: A total of 45 patients (61.0 (52.0; 69.0) years, 26 (57.8%) female) were included after a follow-up time of 85.0 (55.3; 111.0) months. Symptoms included dysphagia (56.0%), dysphonia (51.0%), hoarseness (76.0%), the necessity of throat clearing (73.0%), globus sensation (56.0%) and heartburn (71.0%). Complete GIP eradication was achieved after one session in 25 (55.6%), repetitive sessions were needed in the remaining cases. Fourteen patients (31.1%) reported a very strong, 11 (24.4%) a strong and 8 patients (17.8%) an intermediate improvement; five patients did not benefit. The most apparent improvement was seen regarding hoarseness (from 2.6 ± 1.7 to 1.2 ± 1.3), the necessity of throat clearing (from 2.6 ± 1.7 to 1.1 ± 1.3), globus sensation (from 2.0 ± 1.9 to 0.9 ± 1.3) and heartburn (from 2.5 ± 1.8 to 1.4 ± 1.6). Adverse events included post-endoscopic pain (n = 6, 13.3%) and purulent pharyngitis (n = 2, 4.4%). CONCLUSIONS: The APC therapy of GIP is safe and leads to long-term relief of laryngopharyngeal symptoms in carefully selected patients.

Pelvic inlet area is associated with birth mode.

INTRODUCTION: To determine whether a pelvis is wide enough for spontaneous delivery has long been the subject of obstetric research. A number of variables have been proposed as predictors, all with limited accuracy. In this study, we use a novel three-dimensional (3D) method to measure the female pelvis and assess which pelvic features influence birth mode. We compare the 3D pelvic morphology of women who delivered vaginally, women who had cesarean sections, and nulliparous women. The aim of this study is to identify differences in pelvic morphology between these groups. MATERIAL AND METHODS: This observational study included women aged 50 years and older who underwent a CT scan of the pelvis for any medical indication. We recorded biometric data including height, weight, and age, and obtained the obstetric history. The bony pelvis was extracted from the CT scans and reconstructed in three dimensions. By placing 274 landmarks on each surface model, the pelvises were measured in detail. The pelvic inlet was measured using 32 landmarks. The trial was registered at the German Clinical Trials Register DRKS (DRKS00017690). RESULTS: For this study, 206 women were screened. Exclusion criteria were foreign material in the bony pelvis, unknown birth mode, and exclusively preterm births. Women who had both a vaginal birth and a cesarean section were excluded from the group comparison. We compared the pelvises of 177 women between three groups divided by obstetric history: vaginal births only (n = 118), cesarean sections only (n = 21), and nulliparous women (n = 38). The inlet area was significantly smaller in the cesarean section group (mean = 126.3 cm2 ) compared with the vaginal birth group (mean = 134.9 cm2 , p = 0.002). The nulliparous women were used as a control group: there was no statistically significant difference in pelvic inlet area between the nulliparous and vaginal birth groups. CONCLUSIONS: By placing 274 landmarks on a pelvis reconstructed in 3D, a very precise measurement of the morphology of the pelvis is possible. We identified a significant difference in pelvic inlet area between women with vaginal delivery and those with cesarean section. A unique feature of this study is the method of measurement of the bony pelvis that goes beyond linear distance measurements as used in previous pelvimetric studies.

Cook Inlet beluga whale Delphinapterus leucas with valvular endocarditis, encephalitis, rhabdomyolysis, heavy parasitism and fungal dermatitis.

This is a case report of a Cook Inlet beluga whale Delphinapterus leucas found dead stranded on September 28, 2020 in Turnagain Arm, Alaska. This subadult male had valvular endocarditis, encephalitis, rhabdomyolysis, myoglobinuric nephropathy, severe parasitism and fungal dermatitis. Erysipelothrix rhusiopathiae was detected in the heart lesion, eye and external swabs. The level of infection and parasitism in this individual is markedly higher than what has been found in other Cook Inlet belugas, suggesting immunosuppression.

Heterotopic Gastric Mucosa in the Proximal Esophagus: Prospective Study and Systematic Review on Relationships with Endoscopic Findings and Clinical Data.

Cervical inlet patches (CIP) are common endoscopic findings with uncertain pathogenesis and clinical significance. We aimed to perform a systematic review and prospective study of clinical data and endoscopic findings related to CIP. It was a prospective single-center study conducted between 10/01/2017 and 9/01/2018. Forty patients with histopathologically confirmed CIP were compared with 222 individuals in the reference group. The systematic review was executed in accordance with the PRISMA guideline. Alcohol consumption tended to be higher among patients with CIP (3.0 ± 4.6 vs. 1.9 ± 5.0 standard drinks/week CIP patients and reference group, respectively; p < 0.001). Dysphagia was more frequent among patients with CIP (25% vs. 1.4%, CIP patients and reference group, respectively; p < 0.001), and sore throat and hoarseness were less frequent in patients with CIP (17.5% vs. 26.6% CIP patients and reference group, respectively; p < 0.01). In the multivariate regression analysis, the only risk factor of CIP occurrence was dysphagia (OR 21.9, 95%CI 4.9-98.6; p < 0.001). Sore throat and hoarseness were a reverse-risk factor of CIP diagnosis (OR 0.3, 95%CI 0.1-0.93; p = 0.04). Clinical data and coexisting endoscopic findings were not related to CIP. In the presented study, dysphagia was related to CIP occurrence, and sore throat and hoarseness tended to be less frequent among patients with CIP.

Effects of Head and Neck Alignment and Pharyngeal Anatomy on Epiglottic Inversion During Swallowing in Dysphagic Patients.

The effects of head and neck alignment and pharyngeal anatomy on epiglottic inversion remain unclear. This study investigated the factors involved in epiglottic inversion, including head and neck alignment and pharyngeal anatomy, in patients with dysphagia. Patients with a chief complaint of dysphagia and who underwent videofluoroscopic swallowing study at our hospital from January to July 2022 were enrolled. They were divided into three groups based on the degree of epiglottic inversion as the complete-inversion (CI), partial-inversion (PI), and non-inversion group (NI) groups. Data were compared among the three groups; a total of 113 patients were analyzed. The median age was 72.0 (IQR: 62.0-76.0) years; 41 (36.3%) and 72 (63.7%) were women and men, respectively. There were in 45 (39.8%) patients in the CI, 39 (34.5%) in the PI, and 29 (25.7%) in the NI groups, respectively. Single-variable analysis revealed significant relation to epiglottic inversion of Food Intake LEVEL Scale score, penetration-aspiration score with 3-mL thin liquid bolus, epiglottic vallecula and pyriform sinus residue, hyoid position and displacement during swallowing, pharyngeal inlet angle (PIA), epiglottis to posterior pharyngeal wall distance, and body mass index. Logistic regression analysis with complete epiglottic inversion as the dependent variable revealed the X coordinate at maximum hyoid elevation position during swallowing and PIA as significant explanatory variables. These results suggest that epiglottic inversion is constrained in patients with dysphagia who have poor head and neck alignment or posture and a narrow pharyngeal cavity just before swallowing.

Quantitative Detection of Natural Rubber Content in Eucommia ulmoides by Portable Pyrolysis-Membrane Inlet Mass Spectrometry.

Eucommia ulmoides gum (EUG) is a natural polymer predominantly consisting of trans-1,4-polyisoprene. Due to its excellent crystallization efficiency and rubber-plastic duality, EUG finds applications in various fields, including medical equipment, national defense, and civil industry. Here, we devised a portable pyrolysis-membrane inlet mass spectrometry (PY-MIMS) approach to rapidly, accurately, and quantitatively identify rubber content in Eucommia ulmoides (EU). EUG is first introduced into the pyrolyzer and pyrolyzed into tiny molecules, which are then dissolved and diffusively transported via the polydimethylsiloxane (PDMS) membrane before entering the quadrupole mass spectrometer for quantitative analysis. The results indicate that the limit of detection (LOD) for EUG is 1.36 µg/mg, and the recovery rate ranges from 95.04% to 104.96%. Compared to the result of pyrolysis-gas chromatography (PY-GC), the average relative error is 1.153%, and the detection time was reduced to less than 5 min, demonstrating that the procedure was reliable, accurate, and efficient. The method has the potential to be employed to precisely identify the rubber content of natural rubber-producing plants such as Eucommia ulmoides, Taraxacum kok-saghyz (TKS), Guayule, and Thorn lettuce.