Access to chiral dihydrophenanthridines via a palladium(0)-catalyzed Suzuki coupling and C-H arylation cascade reaction using new chiral-bridged biphenyl bifunctional ligands.

A class of chiral-bridged biphenyl phosphine-carboxylate bifunctional ligands CB-Phos has been developed and successfully applied to Pd(0)-catalyzed single enantioselective C-H arylation and a one pot cascade reaction involving Suzuki cross-coupling and C-H arylation. The catalytic system provides a new and convenient way for the synthesis of versatile chiral dihydrophenanthridines with rich structures and broad functional group tolerance. Good to excellent yields with high enantioselectivities were generally achieved. The reaction mechanism of the cascade reaction was also preliminarily discussed.

Carbon-based molecular properties efficiently predicted by deep learning-based quantum chemical simulation with large language models.

The prediction of thermodynamic properties of carbon-based molecules based on their geometrical conformation using fluctuation and density functional theories has achieved great success in the field of energy chemistry, while the excessive computational cost provides both opportunities and challenges for the integration of machine learning. In this work, a deep learning-based quantum chemical prediction model was constructed for efficient prediction of thermodynamic properties of carbon-based molecules. We constructed a novel framework - encoding the 3D information into a large language model (LLM), which in turn generates a 2D SMILES string, while embedding a learnable encoding designed to preserve the integrity of the original 3D information, providing better structural information for the model. Additionally, we have designed an equivariant learning module to encompass representations of conformations and feature learning for conformational sampling. This framework aims to predict thermodynamic properties more accurately than learning from 2D topology alone, while providing faster computational speeds than conventional simulations. By combining machine learning and quantum chemistry, we pioneer efficient practical applications in the field of energy chemistry. Our model advances the integration of data-driven and physics-based modeling to unlock novel insights into carbon-based molecules.

Abnormal coagulation after hepatectomy in patients with normal preoperative coagulation function.

BACKGROUND: To explore the risk factors for postoperative abnormal coagulation (PAC) and establish a predictive model for patients with normal preoperative coagulation function who underwent hepatectomy. MATERIALS AND METHODS: A total of 661 patients with normal preoperative coagulation function who underwent hepatectomy between January 2015 and December 2021 at the First Affiliated Hospital of Sun Yat-sen University were divided into two groups: the postoperative abnormal coagulation group (PAC group, n = 362) and the normal coagulation group (non-PAC group, n = 299). Univariate and multivariate logistic analyses were used to identify the risk factors for PAC. RESULTS: The incidence of PAC in 661 patients who underwent hepatectomy was 54.8% (362/661). The least absolute shrinkage and selection operator (LASSO) method was used for multivariate logistic regression analysis. The preoperative international normalized ratio (INR), intraoperative succinyl gelatin infusion and major hepatectomy were found to be independent risk factors for PAC. A nomogram for predicting the PAC after hepatectomy was constructed. The model presented a receiver operating characteristic (ROC) curve of 0.742 (95% confidence interval (CI): 0.697-0.786) in the training cohort. The validation set demonstrated a promising ROC of 0.711 (95% CI: 0.639-0.783), and the calibration curve closely approximated the true incidence. Decision curve analysis (DCA) was performed to assess the clinical usefulness of the predictive model. The risk of PAC increased when the preoperative international normalized ratio (INR) was greater than 1.025 and the volume of intraoperative succinyl gelatin infusion was greater than 1500 ml. CONCLUSION: The PAC is closely related to the preoperative INR, intraoperative succinyl gelatin infusion and major hepatectomy. A three-factor prediction model was successfully established for predicting the PAC after hepatectomy.

Circ_0001671 regulates prostate cancer progression through miR-27b-3p/BLM axis.

Prostate cancer (PCa) ranks as the second most prevalent cancer among males globally. However, the exact mechanisms underlying its progression remain inadequately elucidated. The present study sought to investigate the role and underlying molecular mechanism of hsa_circ_0001671 (circ_0001671) in the pathogenic behavior of PCa cells. Guided by the ceRNA theory, miR-27b-3p was employed to identify circRNAs that could potentially regulate Bloom Syndrome Protein (BLM). A series of experimental approaches including bioinformatics, luciferase assays, Fluorescent In Situ Hybridization (FISH), RNA-pulldown, and RNA Immunoprecipitation (RIP) were utilized to validate the miRNA sponge function of circ_0001671. Divergent primer PCR, RNase R treatments, and Sanger sequencing were conducted for the identification of circ_0001671. Quantitative RT-PCR and Western blot analyses were performed to validate gene expression levels. Both in vitro and in vivo experiments were conducted to assess the functional role of circ_0001671 in PCa cells.It was observed that the expression levels of circ_0001671 and BLM were significantly elevated in PCa tissues and cell lines, whereas miR-27b-3p showed decreased expression. Circ_0001671 was found to promote cellular proliferation, migration, and invasion, while inhibiting apoptosis. In vivo assays confirmed that circ_0001671 facilitated tumor growth. Further mechanistic studies revealed that circ_0001671 acted as a competing endogenous RNA (ceRNA) for BLM by sponging miR-27b-3p. The oncogenic role of circ_0001671 in PCa was shown to be modulated through the miR-27b-3p/BLM axis. In conclusion, circ_0001671 exerts an oncogenic effect in prostate cancer through the regulation of BLM by sponging miR-27b-3p, thus suggesting a novel molecular target for the treatment of PCa.

Objective Noninvasive Measurement of the Volumizing Effect of a Dermal Filler: An In Vivo Study.

BACKGROUND: Information about the volumizing effects of dermal fillers is critical for physicians' understanding of product features and prudent decision-making in clinical practice. It is important for material engineers to develop and optimize new dermal fillers, especially when comparing the physiochemical properties of a new product with those of existing fillers that are used worldwide. OBJECTIVE: This study aimed to establish a reliable, noninvasive method for in vivo quantitative evaluation of the filling effect in order to predict possible effectiveness after filler injection and to evaluate the degradation trend over time. METHODS: A rabbit model of ear injection with dermal fillers was established. Hyaluronic acid (HA) filler was injected into the subcutaneous layer of rabbit ears, resulting in a stable skin bulge. Ultrasonography was used to noninvasively measure the skin bulge for volume calculation; the volume change was analyzed periodically until 38 weeks. Pathological examination, the gold standard, was performed to confirm degradation. RESULTS: The immediate volumizing effect of HA filler injection was macroscopically observed as a local skin bulge. Ultrasound was able to precisely detect the shape of the filler and calculate the length, width, and height of the skin bulge at each time point. The degree of uplift and amount of residual samples in the pathological evaluation were consistent with the results of morphological observation using ultrasound. CONCLUSION: Evaluation of the volume impact of dermal filler through the rabbit ear injection model evaluation enables material science evaluation in the early stage of material development, and has certain clinical reference value. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Fabricating Ultrastrong Carbon Nanotube Fibers via a Microwave Welding Interface.

Liquid crystal wet-spun carbon nanotube fibers (CNTFs) offer notable advantages, such as precise alignment and scalability. However, these CNTFs usually suffer premature failure through intertube slippage due to the weak interfacial interactions between adjacent shells and bundles. Herein, we present a microwave (MW) welding strategy to enhance intertube interactions by partially carbonizing interstitial heterocyclic aramid polymers. The resulting CNTFs exhibit ultrahigh static tensile strength (6.74 ± 0.34 GPa) and dynamic tensile strength (9.52 ± 1.31 GPa), outperforming other traditional high-performance fibers. This work provides a straightforward yet effective approach to strengthening CNTFs for advanced engineering applications.

[Progress of anterior subcutaneous internal fixation in the treatment of anterior pelvic ring injury].

Anterior subcutaneous internal fixation (INFIX) is one of the current representatives of minimally invasive fixation of injuries to the anterior pelvic ring. The nail insertion point of this technique is located at the anterior inferior iliac spinous screw, with an angle of 30° outward and 20° backward. Screw in at an angle, and note that the screw head should be above the deep fascia and maintain a safe distance of 20 to 25 mm from the bone surface. Its improved versions include 3 or 4 nails INFIX with added pubic tubercle screws, unilateral INFIX, short-rod INFIX, and double INFIX. These improvements further enhance stability. The lateral femoral cutaneous nerve (LFCN) is relatively easy to be damaged during anatomy, so special attention should be paid during the operation. Biomechanical stability has advantages over external fixation, and its application is flexible. It is not limited to pubic ramus fracture, symphyseal separation, etc. It also plays an important role in combined anterior and posterior ring fixation. It can be combined with posterior sacroiliac screws, iliac lumbar screws, etc. Fixed etc. Good clinical results have also been reported in children, pregnant women, and people with contraindications for subcutaneous connecting rods. In addition, the current application of robots, reduction frames and other technologies has greatly reduced the difficulty of reduction and improved the quality of closed reduction, making it possible to fix complex pelvic fracture. This technique has high reduction quality and is as effective as traditional steel plates. A common complication is LFCN injury. Careful exposure and adjustment of the position and depth of internal fixation during surgery can effectively avoid this complication.

Non-equilibrium compression achieving high sensitivity and linearity for iontronic pressure sensors.

Flexible pressure sensors with high sensitivity and linearity are highly desirable for robot sensing and human physiological signal detection. However, the current strategies for stabilizing axial microstructures (e.g., micro-pyramids) are mainly susceptible to structural stiffening during compression, thereby limiting the realization of high sensitivity and linearity. Here, we report a bending-induced non-equilibrium compression process that effectively enhances the compressibility of microstructures, thereby crucially improving the efficiency of interfacial area growth of electric double layer (EDL). Based on this principle, we fabricate an iontronic flexible pressure sensor with vertical graphene (VG) array electrodes. Ultra-high sensitivity (185.09 kPa-1) and linearity (R2 = 0.9999) are realized over a wide pressure range (0.49 Pa-66.67 kPa). It also exhibits remarkable mechanical stability during compression and bending. The sensor is successfully employed in a robotic gripping task to recognize the targets of different materials and shapes based on a multilayer perception (MLP) neural network. It opens the door to realizing haptic sensing capabilities for robotic hands and prosthetic limbs.

Modified activated carbon material-assisted electrochemical disinfection effectively inactivate antibiotic-resistant bacteria.

ABSTRACTThe production and widespread transmission of antibiotic-resistant bacteria (ARB) pose an emerging threat to global public health. Electrochemical disinfection (ED) is an environmentally friendly disinfection technology widely utilized to inactivate ARB. This study explored the effect of modified activated carbon material (MACM) assisted ED on multi-ARB inactivation and the regeneration ability. The established ED technique was proven to be effective in inactivating multi-resistant ARB. Specifically, a 5-log ARB removal was achieved within 30 min treatment of MACM-assisted ED at 2.5 V. Additionally, no ARB regrowth was observed, indicating a permanent inactivation of ARB. The high level of reactive chlorine induced by MACM electrolysis was stressful to the ARB. Reactive chlorine led to overproduction of reactive oxygen species and damage of cell membranes in cells, accelerating the inactivation of ARB. Conclusively, the MACM-assisted ED method demonstrated efficient performance for ARB inactivation, implying this method is a promising alternative to traditional disinfection methods in countering ARB transmission.

Photocatalytic Generation of Carbocation from Thiols and Application to Cross-Nucleophile Coupling.

Represented herein is a simple thiol identified as an effective precursor to photochemically form a carbocation. Thanks to the thiyl radical rapid transformation to disulfide, which serves not only to stabilize the generated thiyl radical but also to allow the second electron transfer to form a carbocation. The resulting carbocations, including primary benzylic, secondary, and tertiary carbocations, can smoothly couple with nitrogen, oxygen, and carbon nucleophilic coupling partners as well as complex drug molecules, accompanied by elemental sulfur formation in air.

Modular Access to Chiral Amines via Imine Reductase-Based Photoenzymatic Catalysis.

The development of catalysts serves as the cornerstone of innovation in synthesis, as exemplified by the recent discovery of photoenzymes. However, the repertoire of naturally occurring enzymes repurposed by direct light excitation to catalyze new-to-nature photobiotransformations is currently limited to flavoproteins and keto-reductases. Herein, we shed light on imine reductases (IREDs) that catalyze the remote C(sp3)-C(sp3) bond formation, providing a previously elusive radical hydroalkylation of enamides for accessing chiral amines (45 examples with up to 99% enantiomeric excess). Beyond their natural function in catalyzing two-electron reductive amination reactions, upon direct visible-light excitation or in synergy with a synthetic photoredox catalyst, IREDs are repurposed to tune the non-natural photoinduced single-electron radical processes. By conducting wet mechanistic experiments and computational simulations, we unravel how engineered IREDs direct radical intermediates toward the productive and enantioselective pathway. This work represents a promising paradigm for harnessing nature's catalysts for new-to-nature asymmetric transformations that remain challenging through traditional chemocatalytic methods.

A Scoping Review of the Epidemiology, Management, and Outcomes of Golf-Related Fractures.

ABSTRACT: Golf is a popular sport; however, there is a paucity of data in relation to golf-associated fractures, and the rate and timing of returning to golf. The aim of this review is to describe golf-associated fractures, including epidemiology, management, and timing of returning to golf following treatment. A literature search was performed using MEDLINE/PubMed, Embase, and Web of Science. Data were extracted and summarized in a narrative synthesis. A total of 436 articles were identified with an initial search of which 58 met the inclusion criteria. Twelve anatomical sites of golf swing-related fractures were identified, of which 10 sites were specific for stress fractures. The most common sites of golf swing-related stress fractures were the ribs followed by the hook of hamate. There was a common theme of delay to diagnosis, being initially assigned to a soft tissue injury. Most golfers with swing-related stress fractures were able to return to golf with the exception of osteoporotic associated vertebral stress fractures. Timing of returning to golf was between 4 and 12 months for most of the golfers with stress fractures following conservative management. Operative intervention was an option of hook of hamate nonunion, following a stress fracture, and tibial shaft stress fractures. Golf equipment-related fractures were not rare and were associated with major trauma and in some cases associated with significant persistent morbidity. Golf-related stress fractures commonly involve the ribs and hook of hamate; knowledge of this may aid in early diagnosis and appropriate treatment when symptomatic golfers are encountered. Although golf is a noncontact sport, fractures associated with golf equipment can be life changing, and safety training guidelines should be established.

2D Janus Polarization Functioned by Mechanical Force.

2D polarization materials have emerged as promising candidates for meeting the demands of device miniaturization, attributed to their unique electronic configurations and transport characteristics. Although the existing inherent and sliding mechanisms are increasingly investigated in recent years, strategies for inducing 2D polarization with innovative mechanisms remain rare. This study introduces a novel 2D Janus state by modulating the puckered structure. Combining scanning probe microscopy, transmission electron microscopy, and density functional theory calculations, this work realizes force-triggered out-of-plane and in-plane dipoles with distorted smaller warping in GeSe. The Janus state is preserved after removing the external mechanical perturbation, which could be switched by modulating the sliding direction. This work offers a versatile method to break the space inversion symmetry in a 2D system to trigger polarization in the atomic scale, which may open an innovative insight into configuring novel 2D polarization materials.

Pan-cancer analysis of prognostic and immunological role of IL4I1 in human tumors: a bulk omics research and single cell sequencing validation.

BACKGROUND: Interleukin-4 inducible gene 1 (IL4I1) regulates tumor progression in numerous tumor types. However, its correlation with immune infiltration and prognosis of patients in a pan-cancer setting remains unclear. METHODS: Data from the Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), UALCAN, Clinical Proteomic Tumor Analysis Consortium (CPTAC), Gene Expression Omnibus (GEO), cBioPortal, Cancer Single-cell State Atlas (CancerSEA), and Tumor IMmune Estimation Resource(TIMER) databases were used to evaluate IL4I1 expression, clinical features and prognostic effects, gene set enrichment, and correlation with immune cell infiltration, as well as the relationship between IL4I1 methylation and expression and survival prognosis. Correlations with 192 anticancer drugs were also analyzed. RESULTS: IL4I1 was significantly overexpressed in the majority of tumors, and the imbalance of IL4I1 was significantly correlated with overall survival and pathological stage. Moreover, total IL4I1 protein was increased in cancer. Therefore, IL4I1 may be used as a prognostic biomarker or protective factor in numerous types of cancer. The methylation level of IL4I1 may also be used as a prognostic marker. The functional enrichment of IL4I1 was closely related to the immunomodulatory pathway. In addition, the level of tumor-associated macrophage infiltration was positively correlated with the expression of IL4I1 in pan-cancerous tissues. scRNA-seq analysis suggested that IL4I1 differ significantly among different cells in the tumor microenvironment and was most enriched in macrophages. Various immune checkpoint genes were positively correlated with IL4I1 expression in most tumors. In addition, patients with high IL4I1 expression may be resistant to BMS-754807 and docetaxel, but sensitive to temozolomide. CONCLUSION: IL4I1 may play a role as promoter of cancer and prognostic indicator in patients. High expression of IL4I1 is associated with the state of tumor immunosuppression and may contribute to tumor-associated macrophage invasion. Therefore, IL4I1 may be a new therapeutic target for the treatment and prognosis of patients with cancer.

Strong Acceptors Based on Derivatives of Benzothiadiazoloimidazole.

Despite the rapid progression of organic semiconductors, developing high-air-stability n-type organic semiconductors are still challenging. Herein, novel strong acceptors based on benzothiadiazoloimidazole units are reported. The results reveal that the strong acceptor BTI-NDI-BTI-a has good solubility and high electron affinity (3.94 eV), accompanied by 1D slipped-stacking crystals. Notably, the material presents promising potential for developing into air-stable n-type organic semiconductor materials.

Bioactive Alkaloids from the Mangrove-Derived Fungus Nigrospora oryzae SYSU-MS0024.

Chemical investigation of marine fungus Nigrospora oryzae SYSU-MS0024 cultured on solid-rice medium led to the isolation of three new alkaloids, including a pair of epimers, nigrosporines A (1) and B (2), and a pair of enantiomers, (+)-nigrosporine C (+)-3, and (-)-nigrosporine C (-)-3, together with eight known compounds (4-11). Their structures were elucidated based on extensive mass spectrometry (MS) and 1D/2D nuclear magnetic resonance (NMR) spectroscopic analyses and compared with data in the literature. The absolute configurations of compounds 1-3 were determined by a combination of electronic circular dichroism (ECD) calculations, Mosher's method, and X-ray single-crystal diffraction technique using Cu Kα radiation. In bioassays, compound 2 exhibited moderate inhibition on NO accumulation induced by lipopolysaccharide (LPS) on BV-2 cells in a dose-dependent manner at 20, 50, and 100 µmol/L and without cytotoxicity in a concentration of 100.0 µmol/L. Moreover, compound 2 also showed moderate acetylcholinesterase (AChE) inhibitory activities with IC50 values of 103.7 µmol/L. Compound 5 exhibited moderate antioxidant activity with EC50 values of 167.0 µmol/L.

A conserved molecular logic for neurogenesis to gliogenesis switch in the cerebral cortex.

During development, neural stem cells in the cerebral cortex, also known as radial glial cells (RGCs), generate excitatory neurons, followed by production of cortical macroglia and inhibitory neurons that migrate to the olfactory bulb (OB). Understanding the mechanisms for this lineage switch is fundamental for unraveling how proper numbers of diverse neuronal and glial cell types are controlled. We and others recently showed that Sonic Hedgehog (Shh) signaling promotes the cortical RGC lineage switch to generate cortical oligodendrocytes and OB interneurons. During this process, cortical RGCs generate intermediate progenitor cells that express critical gliogenesis genes Ascl1, Egfr, and Olig2. The increased Ascl1 expression and appearance of Egfr+ and Olig2+ cortical progenitors are concurrent with the switch from excitatory neurogenesis to gliogenesis and OB interneuron neurogenesis in the cortex. While Shh signaling promotes Olig2 expression in the developing spinal cord, the exact mechanism for this transcriptional regulation is not known. Furthermore, the transcriptional regulation of Olig2 and Egfr has not been explored. Here, we show that in cortical progenitor cells, multiple regulatory programs, including Pax6 and Gli3, prevent precocious expression of Olig2, a gene essential for production of cortical oligodendrocytes and astrocytes. We identify multiple enhancers that control Olig2 expression in cortical progenitors and show that the mechanisms for regulating Olig2 expression are conserved between the mouse and human. Our study reveals evolutionarily conserved regulatory logic controlling the lineage switch of cortical neural stem cells.

Assessing agricultural greenhouse gas emission mitigation by scaling up farm size: An empirical analysis based on rural household survey data.

Agriculture is a major contributor to greenhouse gas (GHG) emissions. Farm size affects agricultural production inputs and thus has impacts on agricultural GHG emissions. However, the effects and mechanisms behind this are still unclear. In this paper, we identified the effects and mechanisms of farm size on agricultural GHG emissions, based on survey data about over 20,000 rural households in China from 2009 to 2016. Firstly, we calculated the agricultural CO2, CH4, and N2O emissions using the life-cycle analysis (LCA). Secondly, the impacts of farm size on GHG emissions intensity were explored with a fixed effect model, based on the long-term rural household survey data. Finally, the mechanisms were tested by the mediation effect model. The results showed that a 1 % increase in farm size, on average, could reduce the GHG emissions intensity of rural households by 0.245 % from 2009 to 2016. The mechanism analysis showed that the larger farm size reduced GHG emissions intensity mainly by reducing the non-fixed input intensity and raising fixed input investment. By identifying the impacts and mechanisms of farm size on agricultural GHG emissions, this paper aims to provide insights for policymakers to achieve China's goal of reaching carbon neutrality by 2060.

Oral vitamin A supplements to prevent acute upper respiratory tract infections in children up to seven years of age.

BACKGROUND: According to global prevalence analysis studies, acute upper respiratory tract infections (URTIs) are the most common acute infectious disease in children, especially in preschool children. Acute URTIs lead to an economic burden on families and society. Vitamin A refers to the fat-soluble compound all-trans-retinol and also represents retinol and its active metabolites. Vitamin A interacts with both the innate immune system and the adaptive immune system and improves the host's defences against infections. Correlation studies show that serum retinol deficiency was associated with a higher risk of respiratory tract infections. Therefore, vitamin A supplementation may be important in preventing acute URTIs. OBJECTIVES: To assess the effectiveness and safety of vitamin A supplements for preventing acute upper respiratory tract infections in children up to seven years of age. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, the Chinese Biomedical Literature Database, and two trial registration platforms to 8 June 2023. We also checked the reference lists of all primary studies and reviewed relevant systematic reviews and trials for additional references. We imposed no language or publication restrictions. SELECTION CRITERIA: We included randomised controlled trials (RCTs), which evaluated the role of vitamin A supplementation in the prevention of acute URTIs in children up to seven years of age. DATA COLLECTION AND ANALYSIS: We used the standard methodological procedures expected by Cochrane. MAIN RESULTS: We included six studies (27,351 participants). Four studies were RCTs and two were cluster-RCTs. The included studies were all conducted in lower-middle-income countries (two in India, two in South Africa, one in Ecuador, and one in Haiti). Three studies included healthy children who had no vitamin A deficiency, one study included children born to HIV-infected women, one study included low-birthweight neonates, and one study included children in areas with a high local prevalence of malnutrition and xerophthalmia. In two studies, vitamin E was a co-treatment administered in addition to vitamin A. We judged the included studies to be at either a high or unclear risk of bias for random sequence generation, incomplete outcome data, and blinding. Primary outcomes Six studies reported the incidence of acute URTIs during the study period. Five studies reported the number of acute URTIs over a period of time, but there was population heterogeneity and the results were presented in different forms, therefore only three studies were meta-analysed. We are uncertain of the effect of vitamin A supplementation on the number of acute URTIs over two weeks (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.92 to 1.09; I2 = 44%; 3 studies, 22,668 participants; low-certainty evidence). Two studies reported the proportion of participants with an acute URTI. We are uncertain of the effect of vitamin A supplementation on the proportion of participants with an acute URTI (2 studies, 15,535 participants; low-certainty evidence). Only one study (116 participants) reported adverse events. No infant in either the placebo or vitamin A group was found to have feeding difficulties (failure to feed or vomiting), a bulging fontanelle, or neurological signs before or after vitamin A administration (very low-certainty evidence). Secondary outcomes Two studies (296 participants) reported the severity of subjective symptoms, presented by the mean duration of acute URTI. Vitamin A may have little to no effect on the mean duration of acute URTI (very low-certainty evidence). AUTHORS' CONCLUSIONS: The evidence for the use of vitamin A supplementation to prevent acute URTI is uncertain, because population, dose and duration of interventions, and outcomes vary between studies. From generally very low- to low-certainty evidence, we found that there may be no benefit in the use of vitamin A supplementation to prevent acute URTI in children up to seven years of age. More RCTs are needed to strengthen the current evidence. Future research should report over longer time frames using validated tools and consistent reporting, and ensure adequate power calculations, to allow for easier synthesis of data. Finally, it is important to assess vitamin A supplementation for preschool children with vitamin A deficiency.