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ACS Central Science Jun 2024Electron transport chains (ETCs) are ubiquitous in nearly all living systems. Replicating the complexity and control inherent in these multicomponent systems using...
Electron transport chains (ETCs) are ubiquitous in nearly all living systems. Replicating the complexity and control inherent in these multicomponent systems using ensembles of small molecules opens up promising avenues for molecular therapeutics, catalyst design, and the development of innovative energy conversion and storage systems. Here, we present a noncovalent, multistep artificial electron transport chains comprising cyclo[8]pyrrole (), a -aryl hexaphyrin(1.0.1.0.1.0) (naphthorosarin ), and the small molecules I and trifluoroacetic acid (TFA). Specifically, we show that 1) electron transfer occurs from to give I upon the addition of I, 2) proton-coupled electron transfer (PCET) from to give and upon the addition of TFA to a dichloromethane mixture of and , and 3) that further, stepwise treatment of and with I and TFA promotes electron transport from to give first I and then and . The present findings are substantiated through UV-vis-NIR, H NMR, electron paramagnetic resonance (EPR) spectroscopic analyses, cyclic voltammetry studies, and DFT calculations. Single-crystal structure analyses were used to characterize compounds in varying redox states.
PubMed: 38947209
DOI: 10.1021/acscentsci.4c00165 -
ACS Central Science Jun 2024
PubMed: 38947201
DOI: 10.1021/acscentsci.4c00459 -
Research Square Jun 2024Human manganese superoxide dismutase (MnSOD) plays a crucial role in controlling levels of reactive oxygen species (ROS) by converting superoxide (O ) to molecular...
Human manganese superoxide dismutase (MnSOD) plays a crucial role in controlling levels of reactive oxygen species (ROS) by converting superoxide (O ) to molecular oxygen (O ) and hydrogen peroxide (H O ) with proton-coupled electron transfers (PCETs). The reactivity of human MnSOD is determined by the state of a key catalytic residue, Tyr34, that becomes post-translationally inactivated by nitration in various diseases associated with mitochondrial dysfunction. We previously reported that Tyr34 has an unusual pK due to its proximity to the Mn metal and undergoes cyclic deprotonation and protonation events to promote the electron transfers of MnSOD. To shed light on the role of Tyr34 MnSOD catalysis, we performed neutron diffraction, X-ray spectroscopy, and quantum chemistry calculations of Tyr34Phe MnSOD in various enzymatic states. The data identifies the contributions of Tyr34 in MnSOD activity that support mitochondrial function and presents a thorough characterization of how a single tyrosine modulates PCET catalysis.
PubMed: 38946943
DOI: 10.21203/rs.3.rs-4494128/v1 -
World Journal of Gastroenterology Jun 2024In this editorial, we respond to a review article by Nabi , in which the authors discussed gastroesophageal reflux (GER) following peroral endoscopic myotomy (POEM)....
In this editorial, we respond to a review article by Nabi , in which the authors discussed gastroesophageal reflux (GER) following peroral endoscopic myotomy (POEM). POEM is presently the primary therapeutic option for achalasia, which is both safe and effective. A few adverse effects were documented after POEM, including GER. The diagnostic criteria were not clear enough because approximately 60% of patients have a long acid exposure time, while only 10% experience reflux symptoms. Multiple predictors of high disease incidence have been identified, including old age, female sex, obesity, and a baseline lower esophageal sphincter pressure of less than 45 mmHg. Some technical steps during the procedure, such as a lengthy or full-thickness myotomy, may further enhance the risk. Proton pump inhibitors are currently the first line of treatment. Emerging voices are increasingly advocating for the routine combining of POEM with an endoscopic fundoplication method, such as peroral endoscopic fundoplication or transoral incisionless fundoplication. However, more research is necessary to determine the safety and effectiveness of these procedures in the long term for patients who have undergone them.
Topics: Humans; Esophageal Achalasia; Esophageal Sphincter, Lower; Esophagoscopy; Fundoplication; Gastroesophageal Reflux; Myotomy; Natural Orifice Endoscopic Surgery; Proton Pump Inhibitors; Risk Factors; Treatment Outcome
PubMed: 38946871
DOI: 10.3748/wjg.v30.i23.2947 -
Chemistry (Weinheim An Der Bergstrasse,... Jul 2024Developing a water-soluble, oxygen-tolerant, and acid-stable synthetic H2 production catalyst is vital for renewable energy infrastructure. To access such an effective...
Developing a water-soluble, oxygen-tolerant, and acid-stable synthetic H2 production catalyst is vital for renewable energy infrastructure. To access such an effective catalyst, we strategically incorporated enzyme-inspired, multicomponent outer coordination sphere elements around the cobaloxime (Cl-Co-X) core with suitable axial coordination (X). Our cobaloximes with axial imidazole or L-histidine coordination in photocatalytic HAT including the construction of anilines via a non-canonical cross-coupling approach is found superior compared to commonly used cobaloxime catalysts. The reversible Co(II)/Co(I) process is influenced by the axial N ligand's nature. Imidazole/ L-histidine with a higher pKa promptly produces H2 upon irradiation, leading to the improved reactivity compared to previously employed axial (di)chloride or pyridine analogue.
PubMed: 38946611
DOI: 10.1002/chem.202401785 -
Inorganic Chemistry Jul 2024An unusual crystalline porous framework constructed from four types of cages, including all-inorganic Keggin-type polyoxometalate (POM) cages [HWO], organic...
An unusual crystalline porous framework constructed from four types of cages, including all-inorganic Keggin-type polyoxometalate (POM) cages [HWO], organic hexamethylenetetramine (Hmt) cages, nanosized silver-Hmt coordination cages, and giant POM-silver-Hmt cages, was hydrothermally synthesized and structurally characterized. The framework features a highly symmetrical structure with one-dimensional nanoscale channels and holds good thermal/solvent stability, which endow it with proton conduction properties and heterogeneous catalytic activity for pyrazole. This paper not only contributes to broadening the structural diversity of cage-based crystalline porous framework materials but also sheds new light on the design of new functional framework materials.
PubMed: 38946338
DOI: 10.1021/acs.inorgchem.4c01579 -
Chemistry (Weinheim An Der Bergstrasse,... Jun 2024As the key component of various energy storage and conversion devices, proton exchange membranes (PEMs) have been attracting significant interest. However, their further...
As the key component of various energy storage and conversion devices, proton exchange membranes (PEMs) have been attracting significant interest. However, their further development is limited by the high cost of perfluorosulfonic acid polymers and the poor stability of acid-dopped non-fluorinated polymers. Recently, a new group of PEMs has been developed by hybridizing polyoxometalates (POMs), a group of super acidic sub-nanoscale metal oxide clusters, with polymers. POMs can serve simultaneously as both proton sponges and stabilizing agents, and their complexation with polymers can further improve polymers' mechanical performance and processability. Enormous efforts have been focused on studying supramolecular complexation or covalent grafting of POMs with various polymers to optimize PEMs in terms of cost, mechanical properties and stabilities. This concept summarizes recent advances in this emerging field and outlines the design strategies and application perspectives employed for using POM-polymer hybrid materials as PEMs.
PubMed: 38945834
DOI: 10.1002/chem.202402262 -
Food Research International (Ottawa,... Aug 2024There is an increasing amount of research into the development of a third generation of iron supplementation using peptide-iron chelates. Peptides isolated from mung...
There is an increasing amount of research into the development of a third generation of iron supplementation using peptide-iron chelates. Peptides isolated from mung bean were chelated with ferrous iron (MBP-Fe) and tested as a supplement in mice suffering from iron-deficiency anemia (IDA). Mice were randomly divided into seven groups: a group fed the normal diet, the IDA model group, and IDA groups treated with inorganic iron (FeSO), organic iron (ferrous bisglycinate, Gly-Fe), low-dose MBP-Fe(L-MBP-Fe), high-dose MBP-Fe(H-MBP-Fe), and MBP mixed with FeSO (MBP/Fe). The different iron supplements were fed for 28 days via intragastric administration. The results showed that MBP-Fe and MBP/Fe had ameliorative effects, restoring hemoglobin (HGB), red blood cell (RBC), hematocrit (HCT), and serum iron (SI) levels as well as total iron binding capacity (TIBC) and body weight gain of the IDA mice to normal levels. Compared to the inorganic (FeSO) and organic (Gly-Fe) iron treatments, the spleen coefficient and damage to liver and spleen tissues were significantly lower in the H-MBP-Fe and MBP/Fe mixture groups, with reparative effects on jejunal tissue. Gene expression analysis of the iron transporters Dmt 1 (Divalent metal transporter 1), Fpn 1 (Ferroportin 1), and Dcytb (Duodenal cytochrome b) indicated that MBP promoted iron uptake. These findings suggest that mung bean peptide-ferrous chelate has potential as a peptide-based dietary supplement for treating iron deficiency.
Topics: Animals; Vigna; Anemia, Iron-Deficiency; Biological Availability; Mice; Ferrous Compounds; Peptides; Iron; Male; Iron Chelating Agents; Hemoglobins; Dietary Supplements; Cation Transport Proteins; Disease Models, Animal; Glycine
PubMed: 38945571
DOI: 10.1016/j.foodres.2024.114602 -
Radiotherapy and Oncology : Journal of... Jun 2024Sacrococcygeal chordomas have high recurrence rates and are challenging to treat.
INTRODUCTION
Sacrococcygeal chordomas have high recurrence rates and are challenging to treat.
METHODS
In this phase II prospective, randomized, stratified trial, the safety and feasibility of hypofractionated ion radiation therapy were investigated. The primary focus was monitored through the incidence of Grade 3-5 NCI-CTC-AE toxicity. Secondary endpoints included local progression-free (LPFS) and overall survival (OS).
RESULTS
The study enrolled 82 patients with primary (87 %) and recurrent (13 %) inoperable or incompletely resected sacral chordomas from January 2013 to July 2022, divided equally into proton therapy (Arm A) and carbon ion beam therapy (Arm B) groups, each receiving a total dose of 64 Gy (RBE) in 16 fractions, 5-6 fractions per week. Overall 74 % of patients received no previous surgery and 66 % of tumors were confirmed by a brachyury staining. The mean and median Gross Tumor Volume at the time of treatment (GTV) was 407 ml and 185 ml, respectively. The median follow-up of the surviving patients was 44.7 months, and the 2-year and 4-year OS rates were 96 % and 81 %, respectively. Factors such as smaller GTV and younger age trended towards better OS. The LPFS after 2-year and 4-year was 84 % and 70 %, respectively. Male gender emerged as a significant predictor of LPFS. There was no significant difference between the treatment groups. We observed five grade IV wound healing disorders (6 %).
CONCLUSION
The initial response rates were promising; however local control was not sustained. More comparative research on fractionation schemes is essential to refine treatment approaches for inoperable sacral chordoma.
PubMed: 38944346
DOI: 10.1016/j.radonc.2024.110418 -
The Journal of Pediatrics Jun 2024To evaluate the influence of proton pump inhibitor (PPI) use on COVID-19 susceptibility and severity in children.
OBJECTIVE
To evaluate the influence of proton pump inhibitor (PPI) use on COVID-19 susceptibility and severity in children.
STUDY DESIGN
This retrospective, case-control study included all children < 21 years undergoing COVID-19 PCR testing at a tertiary children's hospital between March 2020 and January 2023. The main exposure was PPI usage. The primary outcome was COVID-19 infection. The secondary outcome was COVID-19 hospitalization. Log-binomial regressions were used to examine associations between PPI use and these outcomes.
RESULTS
116,209 patients age 8.5±6.2 years underwent 234,867 COVID-19 tests. Current PPI use was associated with a decreased risk of COVID-19 test positivity compared with PPI non-use [RR 0.85 (95% CI 0.76, 0.94), P = 0.002]; however, there was a significant interaction with time of testing, and an effect of PPIs was no longer seen in the final months of the study following lessening of COVID-19 precautions [RR 1.04 (95% CI 0.0.80, 1.36), P = 0.77]. PPI use was not associated with risk of hospitalization in patients positive for COVID-19 after adjusting for other hospitalization risk factors [RR 0.85 (95% CI 0.64, 1.13), P = 0.26].
CONCLUSIONS
We did not find an association between PPI use and increased COVID-19 susceptibility or severity in this pediatric sample. These results provide reassuring evidence that PPIs may not worsen COVID-19 outcomes in children.
PubMed: 38944187
DOI: 10.1016/j.jpeds.2024.114179