MicroRNA-3061 downregulates the expression of PAX7/Wnt/Ca2+ signalling axis genes to induce premature ovarian failure in mice.

The in-depth mechanisms of microRNA regulation of premature ovarian failure (POF) remain unclear. Crispr-cas9 technology was used to construct transgenic mice. The qPCR and Western blot was used to detect the expression level of genes. H&E staining were used to detect ovarian pathological phenotypes. We found that the expression levels of microRNA-3061 were significantly higher in ovarian granulosa cells (OGCs) of POF mouse models than in controls. The miR-3061+/-/AMH-Cre+/- transgenic mice manifested symptoms of POF. RNA-Seq and luciferase reporter assay confirmed that the PAX7 was one of the target genes negatively regulated by microRNA-3061 (miR-3061-5p). Moreover, PAX7 mediated the expression of non-canonical Wnt/Ca2+ signalling pathway by binding to the motifs of promoters to stimulate the transcriptional activation of Wnt5a and CamK2a. In contrast, specific knock-in of microRNA-3061 in OGCs significantly downregulated the expression levels of PAX7 and inhibited the expression of downstream Wnt/Ca2+ signalling pathway. We also discerned a correlation between the expression levels of mRNAs of the Wnt/Ca2+ signalling pathway and the levels of E2 and FSH in POF patients by examining gene expression in the follicular fluid-derived exosomes of women. We confirmed that overexpression of microRNA-3061 induced proliferative inhibition of OGCs and ultimately induced POF in mice by suppressing the transcription factor PAX7 and downregulating expression levels of its downstream Wnt/Ca2+ signalling pathway genes.

Correction of human nonsense mutation via adenine base editing for Duchenne muscular dystrophy treatment in mouse.

Duchenne muscular dystrophy (DMD) is the most prevalent herediatry disease in men, characterized by dystrophin deficiency, progressive muscle wasting, cardiac insufficiency, and premature mortality, with no effective therapeutic options. Here, we investigated whether adenine base editing can correct pathological nonsense point mutations leading to premature stop codons in the dystrophin gene. We identified 27 causative nonsense mutations in our DMD patient cohort. Treatment with adenine base editor (ABE) could restore dystrophin expression by direct A-to-G editing of pathological nonsense mutations in cardiomyocytes generated from DMD patient-derived induced pluripotent stem cells. We also generated two humanized mouse models of DMD expressing mutation-bearing exons 23 or 30 of human dystrophin gene. Intramuscular administration of ABE, driven by ubiquitous or muscle-specific promoters could correct these nonsense mutations in vivo, albeit with higher efficiency in exon 30, restoring dystrophin expression in skeletal fibers of humanized DMD mice. Moreover, a single systemic delivery of ABE with human single guide RNA (sgRNA) could induce body-wide dystrophin expression and improve muscle function in rotarod tests of humanized DMD mice. These findings demonstrate that ABE with human sgRNAs can confer therapeutic alleviation of DMD in mice, providing a basis for development of adenine base editing therapies in monogenic diseases.

Sandwich-like voltametric immunosensing of interleukin-8 based on ß-cyclodextrin/carbon nanotubes and methylthionine chloride@UIO-66 framework.

The level of interleukin-8 (IL-8) in the body is an effective factor for the early diagnosis of acute tubular necrosis and oral tumor. In this work, a novel sandwich-like voltametric immunosensor (SVS) of IL-8 was constructed by preparing ß-cyclodextrin/carbon nanotube (CD/CNT) to immobilize primary antibody (PAb) of IL-8 and UIO-66-NH2 MOFs structure to immobilize second antibody (SAb) and methylene blue (Mb) probe. In this designed SVS, the prepared CD/CNT nanohybrid with large surface area and conductivity can immobilize PAb via simple host-guest recognition, and UIO-66-NH2 provided an ideal platform to accommodate SAb and a large number of Mb molecules as signal-amplifier. In the existence of target IL-8, the current peak of Mb from the SVS assay increases with the increasement of IL-8 level. Through optimizing and adjusting various factors, a wide linearity (0.001-2.5 ng mL-1) and low analytical limit (0.2 pg mL-1) of IL-8 were realized, so it's expected the developed SVS strategy has significant applications for the detection of IL-8.

Cytotoxic lymphocyte-monocyte complex reflects the dynamics of COVID-19 systemic immune response.

SARS-CoV-2 infection causes a variety of clinical manifestations, many of which originate from altered immune responses, either locally or systemically. Immune cell crosstalk occurs mainly in lymphoid organs. However, systemic cell interaction specific to COVID-19 has not been well characterized. Here, by employing single cell RNA sequencing and imaging flow cytometry analysis, we unraveled, in peripheral blood, a heterogeneous group of cell complexes formed by the adherence of CD14+ monocytes to different cytotoxic lymphocytes, including SARS-CoV-2-specific CD8+ T cells, γδT and NKT cells. These lymphocytes attached to CD14+ monocytes that showing enhanced inflammasome activation and pyroptosis-induced cell death in progression stage, whereas in convalescent phase, CD14+ monocytes with elevated antigen presentation potential were targeted by cytotoxic lymphocytes, thereby restricting the excessive immune activation. Collectively, our study reports previously unrecognized cell-cell interplay in SARS-CoV-2 specific immune response, providing new insight into the intricacy of dynamic immune cell interaction representing anti-viral defense.

Enhanced exclusive enteral nutrition delivery during the first 7 days is associated with decreased 28-day mortality in critically ill patients with normal lactate level: a post hoc analysis of a multicenter randomized trial.

BACKGROUND AND AIMS: Exclusive enteral nutrition (EN) is often observed during the first week of ICU admission because of the extra costs and safety considerations for early parenteral nutrition. This study aimed to assess the association between nutrition intake and 28-day mortality in critically ill patients receiving exclusive EN. METHODS: This is a post hoc analysis of a cluster-randomized clinical trial that assesses the effect of implementing a feeding protocol on mortality in critically ill patients. Patients who stayed in the ICUs for at least 7 days and received exclusive EN were included in this analysis. Multivariable Cox hazard regression models and restricted cubic spline models were used to assess the relationship between the different doses of EN delivery and 28-day mortality. Subgroups with varying lactate levels at enrollment were additionally analyzed to address the potential confounding effect brought in by the presence of shock-related hypoperfusion. RESULTS: Overall, 1322 patients were included in the analysis. The median (interquartile range) daily energy and protein delivery during the first week of enrollment were 14.6 (10.3-19.6) kcal/kg and 0.6 (0.4-0.8) g/kg, respectively. An increase of 5 kcal/kg energy delivery was associated with a significant reduction (approximately 14%) in 28-day mortality (adjusted hazard ratio [HR] = 0.865, 95% confidence interval [CI]: 0.768-0.974, P = 0.016). For protein intake, a 0.2 g/kg increase was associated with a similar mortality reduction with an adjusted HR of 0.868 (95% CI 0.770-0.979). However, the benefits associated with enhanced nutrition delivery could be observed in patients with lactate concentration ≤ 2 mmol/L (adjusted HR = 0.804 (95% CI 0.674-0.960) for energy delivery and adjusted HR = 0.804 (95% CI 0.672-0.962) for protein delivery, respectively), but not in those > 2 mmol/L. CONCLUSIONS: During the first week of critical illness, enhanced nutrition delivery is associated with reduced mortality in critically ill patients receiving exclusive EN, only for those with lactate concentration ≤ 2 mmol/L. TRIAL REGISTRATION: ISRCTN12233792, registered on November 24, 2017.

The changing nitrogen landscape of United States streams: Declining deposition and increasing organic nitrogen.

Air quality regulations have led to decreased nitrogen (N) and sulfur deposition across the conterminous United States (CONUS) during the last several decades, particularly in the eastern parts. But it is unclear if declining deposition has altered stream N at large scales. We compared watershed N inputs with N chemistry from over 2,000 CONUS streams where deposition was the largest N input to the watershed. Weighted change analysis showed that deposition declined across most watersheds, especially in the Eastern CONUS. Nationally, declining N deposition was not associated with significant large-scale declines in stream nitrate concentration. Instead, significant increases in stream dissolved organic carbon (DOC) and total organic N (TON) were widespread across regions. Possible mechanisms behind these increases include declines in acidity and/or ionic strength drivers, changes in carbon availability, and/or climate variables. Our results also reveal a declining trend of DOC/TON ratio over the entire study period, primarily influenced by the trend in the Eastern region, suggesting the rate of increase in stream TON exceeded the rate of increase in DOC concentration during this period. Our results illustrate the complexity of nutrient cycling that links long-term atmospheric deposition to water quality. More research is needed to understand how increased dissolved organic N could affect aquatic ecosystems and downstream riverine nutrient export.

RNA-binding proteins in breast cancer: Biological implications and therapeutic opportunities.

RNA-binding proteins (RBPs) refer to a class of proteins that participate in alternative splicing, RNA stability, polyadenylation, localization and translation of RNAs, thus regulating gene expression in post-transcriptional manner. Dysregulation of RNA-RBP interaction contributes to various diseases, including cancer. In breast cancer, disorders in RBP expression and function influence the biological characteristics of tumor cells. Targeting RBPs has fostered the development of innovative therapies for breast cancer. However, the RBP-related mechanisms in breast cancer are not completely clear. In this review, we summarize the regulatory mechanisms of RBPs and their signaling crosstalk in breast cancer. Specifically, we emphasize the potential of certain RBPs as prognostic factors due to their effects on proliferation, invasion, apoptosis, and therapy resistance of breast cancer cells. Most importantly, we present a comprehensive overview of the latest RBP-related therapeutic strategies and novel therapeutic targets that have proven to be useful in the treatment of breast cancer.

Association of energy delivery with short-term survival in mechanically ventilated critically ill adult patients: a secondary analysis of the NEED trial.

BACKGROUND AND AIMS: The optimal energy delivery for mechanically ventilated patients is controversial, particularly during the first week of ICU admission. This study aimed to investigate the association between different caloric adequacy and 28-day mortality in a cohort of critically ill adults on mechanical ventilation. METHODS: This is a secondary analysis of a multicenter, cluster-randomized controlled trial. Eligible patients were divided into four quartiles (Q1-Q4) according to caloric adequacy calculated by the actual average daily energy delivery during the first seven days of ICU stay divided by energy requirement as a percentage. Cox proportional hazards models were used to examine the impact of different quartiles of caloric adequacy on 28-day mortality in the whole cohort and subgroups with different nutritional risk status at enrollment. RESULTS: A total of 1587 patients were included in this study, with an overall 28-day mortality of 15.8%. The average caloric adequacy was 26.3 ± 11.9% (Q1), 52.5 ± 5.5% (Q2), 71.7 ± 6.4% (Q3), 107.0 ± 22.2% (Q4), respectively (p < 0.001 among quartiles). Compared with Q1, Q3 was associated with lower mortality in the unadjusted model (hazard ratio [HR] = 0.536; 95% confidence interval [CI], 0.375-0.767; P = 0.001) and adjusted model (adjusted HR = 0.508; 95% CI, 0.339-0.761; P = 0.001). This association remained valid in the subgroup of high nutritional risk patients (unadjusted HR = 0.387; 95% CI, 0.238-0.627; P < 0.001 and adjusted HR = 0.369; 95% CI, 0.216-0.630; P < 0.001, respectively), but not in those with low risk. CONCLUSIONS: Energy delivery near the 70% energy requirements in the first week of ICU stay was associated with reduced 28-day mortality among mechanically ventilated critically ill patients, especially in patients with high nutrition risk at admission.

The kiwifruit amyloplast proteome (kfALP): a resource to better understand the mechanisms underlying amyloplast biogenesis and differentiation.

The biogenesis and differentiation (B&D) of amyloplasts contributes to fruit flavor and color. Here, remodeling of starch granules, thylakoids and plastoglobules was observed during development and ripening in two kiwifruit (Actinidia spp.) cultivars - yellow-fleshed 'Hort16A' and green-fleshed 'Hayward'. A protocol was developed to purify starch-containing plastids with a high degree of intactness, and amyloplast B&D was studied using label-free-based quantitative proteomic analyses in both cultivars. Over 3000 amyloplast-localized proteins were identified, of which >98% were quantified and defined as the kfALP (kiwifruit amyloplast proteome). The kfALP data were validated by Tandem-Mass-Tag (TMT) labeled proteomics in 'Hort16A'. Analysis of the proteomic data across development and ripening revealed: 1) a conserved increase in the abundance of proteins participating in starch synthesis/degradation during both amyloplast B&D; 2) up-regulation of proteins for chlorophyll degradation and of plastoglobule-localized proteins associated with chloroplast breakdown and plastoglobule formation during amyloplast differentiation; 3) constitutive expression of proteins involved in ATP supply and protein import during amyloplast B&D. Interestingly, two different pathways of amyloplast B&D were observed in the two cultivars. In 'Hayward', significant increases in abundance of photosynthetic- and tetrapyrrole metabolism-related proteins were observed, but the opposite trend was observed in 'Hort16A'. In conclusion, analysis of the kfALP provides new insights into the potential mechanisms underlying amyloplast B&D with relevance to key fruit quality traits in contrasting kiwifruit cultivars.

Assessing multiple factors affecting the gut microbiome structure of very preterm infants.

The composition and diversity of the gut microbiota are essential for the health and development of the immune system of infants. However, there is limited information on factors that influence the gut microbiota of very preterm infants. In this study, we analyzed factors that affect the gut microbiota of very preterm infants. The stool samples from 64 very preterm infants with a gestational age less than 32 weeks were collected for 16S rRNA gene sequencing. The infants were divided according to the delivery mode, antibiotic use during pregnancy, and feeding methods. The abundance of Proteobacteria was high in both cesarean (92.7%) and spontaneous (55.5%) delivery groups and then shifted to Firmicutes after the first week of birth. In addition, Proteobacteria was also the dominant phylum of infant gut microbiome for mothers with antibiotic use, with more than 50% after the first week of birth. In comparison, the dominant phylum for mothers without antibiotic use was Firmicutes. Proteobacteria level was also high in breastfeeding and mixed-feeding groups, consisting of more than 90% of the community. By contrast, Proteobacteria was the dominant phylum at the first week of birth but then shifted to Firmicutes for the formula-fed group. The alterations of gut microbiota in infants can affect their health condition during growth. This study confirmed that the different feeding types, delivery modes, and use of antibiotics during pregnancy can significantly affect the composition of the gut microbiota of very preterm infants.

Improving myopia awareness via school-based myopia prevention health education among Chinese students.

AIM: To investigate the myopia awareness level, knowledge, attitude, and skills at baseline and to implement and evaluate the efficacy of myopia prevention health education among Chinese students. METHODS: A total of 1000 middle school students from 2 middle schools were invited to participate in the study, and myopia prevention health education was conducted. The students were assessed at baseline, followed by a survey. The efficacy of health education was evaluated using the self-comparison method pre- and post-health education. RESULTS: The study included 957 and 850 pre- and post-health education participants, respectively. The baseline knowledge of all respondents on myopic symptoms (87.5%), myopia is a risk of eyes (72.9%), myopia prevention (91.3%), myopia increases with age (86.7%), performing periodic eye examinations (92.8%), and one first, one foot, and one inch (84.8%) significantly increased after health education (P<0.001 for all). However, the percentage of students who still did not think it necessary to take breaks after 30-40min of continuous near work was 27.0%. The opinion that "myopia can be cured" was still present in 38.3%. CONCLUSION: Implementing school-based myopia prevention health education improves knowledge, attitudes, and skills regarding myopia among Chinese middle school students.

Engineered CRISPR-OsCas12f1 and RhCas12f1 with robust activities and expanded target range for genome editing.

The type V-F CRISPR-Cas12f system is a strong candidate for therapeutic applications due to the compact size of the Cas12f proteins. In this work, we identify six uncharacterized Cas12f1 proteins with nuclease activity in mammalian cells from assembled bacterial genomes. Among them, OsCas12f1 (433 aa) from Oscillibacter sp. and RhCas12f1 (415 aa) from Ruminiclostridium herbifermentans, which respectively target 5' T-rich Protospacer Adjacent Motifs (PAMs) and 5' C-rich PAMs, show the highest editing activity. Through protein and sgRNA engineering, we generate enhanced OsCas12f1 (enOsCas12f1) and enRhCas12f1 variants, with 5'-TTN and 5'-CCD (D = not C) PAMs respectively, exhibiting much higher editing efficiency and broader PAMs, compared with the engineered variant Un1Cas12f1 (Un1Cas12f1_ge4.1). Furthermore, by fusing the destabilized domain with enOsCas12f1, we generate inducible-enOsCas12f1 and demonstate its activity in vivo by single adeno-associated virus delivery. Finally, dead enOsCas12f1-based epigenetic editing and gene activation can also be achieved in mammalian cells. This study thus provides compact gene editing tools for basic research with remarkable promise for therapeutic applications.

Shifts in the composition of nitrogen deposition in the conterminous United States are discernable in stream chemistry.

Across the conterminous United States (U.S.), the composition of atmospheric nitrogen (N) deposition is changing spatially and temporally. Previously, deposition was dominated by oxidized N, but now reduced N (ammonia [NH3] + ammonium [NH4+]) is equivalent to oxidized N when deposition is averaged across the entire nation and, in some areas, reduced N dominates deposition. To evaluate if there are effects of this change on stream chemistry at the national scale, estimates of N deposition form (oxidized or reduced) from the National Atmospheric Deposition Program Total Deposition data were coupled with stream measurements from the U.S. Environmental Protection Agency (EPA) National Rivers and Streams Assessments (three stream surveys between 2000 and 2014). A recent fine-scaled N input inventory was used to identify watersheds (<1000 km2) where atmospheric deposition is the largest N source (n = 1906). Within these more atmospherically-influenced watersheds there was a clear temporal shift from a greater proportion of sites dominated by oxidized N deposition to a greater proportion of sites dominated by reduced forms of N deposition. We found a significant positive correlation between oxidized N deposition and stream NO3- concentrations, whereas the correlation between reduced N deposition and stream NO3- concentrations were significant but weaker. Sites dominated by atmospheric inputs of reduced N forms had higher stream total organic N and total N despite lower total N deposition on average. This higher stream concentration of total N is mainly driven by the higher concentration of total organic N, suggesting an interaction between elevated reduced N in deposition and living components of the ecosystem or soil organic matter dynamics. Regardless of the proportion of reduced to oxidized N forms in deposition, stream NH4+ concentrations were generally low, suggesting that N deposited in a reduced form is rapidly immobilized, nitrified and/or assimilated by watershed processes.

Develop a Compact RNA Base Editor by Fusing ADAR with Engineered EcCas6e.

Catalytically inactive CRISPR-Cas13 (dCas13)-based base editors can achieve the conversion of adenine-to-inosine (A-to-I) or cytidine-to-uridine (C-to-U) at the RNA level, however, the large size of dCas13 protein limits its in vivo applications. Here, a compact and efficient RNA base editor (ceRBE) is reported with high in vivo editing efficiency. The larger dCas13 protein is replaced with a 199-amino acid EcCas6e protein, derived from the Class 1 CRISPR family involved in pre-crRNA processing, and conducted optimization for toxicity and editing efficiency. The ceRBE efficiently achieves both A-to-I and C-to-U base editing with low transcriptome off-target in HEK293T cells. The efficient repair of the DMD Q1392X mutation (68.3±10.1%) is also demonstrated in a humanized mouse model of Duchenne muscular dystrophy (DMD) after AAV delivery, achieving restoration of expression for gene products. The study supports that the compact and efficient ceRBE has great potential for treating genetic diseases.

Structure-guided peptide engineering of a positive allosteric modulator targeting the outer pore of TRPV1 for long-lasting analgesia.

Transient receptor potential vanilloid 1 (TRPV1) ion channel is a classic analgesic target, but antagonists of TRPV1 failed in clinical trials due to their side effects like hyperthermia. Here we rationally engineer a peptide s-RhTx as a positive allosteric modulator (PAM) of TRPV1. Patch-clamp recordings demonstrate s-RhTx selectively potentiated TRPV1 activation. s-RhTx also slows down capsaicin-induced desensitization of TRPV1 in the presence of calcium to cause more calcium influx in TRPV1-expressing cells. In addition, our thermodynamic mutant cycle analysis shows that E652 in TRPV1 outer pore specifically interacts with R12 and K22 in s-RhTx. Furthermore, we demonstrate in vivo that s-RhTx exhibits long-lasting analgesic effects in noxious heat hyperalgesia and CFA-induced chronic inflammatory pain by promoting the reversible degeneration of intra-epidermal nerve fiber (IENF) expressing TRPV1 channels in mice, while their body temperature remains unaffected. Our results suggest s-RhTx is an analgesic agent as a PAM of TRPV1.

Electroacupuncture attenuates ac4C modification of P16 mRNA in the ovarian granulosa cells of a mouse model premature ovarian failure.

BACKGROUND: Premature ovarian failure (POF) is a type of pathological aging, which seriously interferes with the fertility of affected women. Electroacupuncture (EA) may have a beneficial effect; however, its mechanism of action is unknown. The purpose of this study was to determine the effect of EA on ovarian function in ovarian granulosa cells (OGCs) in a cyclophosphamide (CTX)-induced mouse model of POF. METHODS: Mice were divided into three groups: wild type (WT) group, CTX group and CTX + EA group. EA was administered under isoflurane anesthesia at CV4, ST36 and SP6 for 30 min every 2 days, 2-3 times per week for a total of 4 weeks. Effects of EA on ovarian weight and level of estrogen were examined. The mRNA and protein expression levels of cell cycle-associated proteins were detected and mRNA modifications were analyzed. RESULTS: EA significantly increased ovarian weight and reduced the proportion of atretic follicles in mice with CTX-induced POF (p < 0.05). EA increased the level of estrogen in the peripheral blood of mice and inhibited the modification of total mRNA N4-acetylcytidine (ac4C). A significant increase in the expression of P16 and N-acetyltransferase 10 (NAT10) and a significant decrease in the expression of Cyclin D (CCND1) and cyclin-dependent kinase 6 (CDK6) were observed in the OGCs of POF mice (p<0.05). After EA, P16 and NAT10 expression was decreased, and CCND1 and CDK6 expression was increased. Finally, EA reduced the ac4C modification of P16 mRNA-specific sites in the OGCs of POF mice. CONCLUSION: This study demonstrated that EA promoted the repair of the ovarian microenvironment by inhibiting the ac4C modification of P16 mRNA to decrease its stability and expression intensity, and by altering the activity of the P16/CDK6/CCND1 axis in OGCs.

Mini-dCas13X-mediated RNA editing restores dystrophin expression in a humanized mouse model of Duchenne muscular dystrophy.

Approximately 10% of monogenic diseases are caused by nonsense point mutations that generate premature termination codons (PTCs), resulting in a truncated protein and nonsense-mediated decay of the mutant mRNAs. Here, we demonstrate a mini-dCas13X-mediated RNA adenine base editing (mxABE) strategy to treat nonsense mutation-related monogenic diseases via A-to-G editing in a genetically humanized mouse model of Duchenne muscular dystrophy (DMD). Initially, we identified a nonsense point mutation (c.4174C>T, p.Gln1392*) in the DMD gene of a patient and validated its pathogenicity in humanized mice. In this model, mxABE packaged in a single adeno-associated virus (AAV) reached A-to-G editing rates up to 84% in vivo, at least 20-fold greater than rates reported in previous studies using other RNA editing modalities. Furthermore, mxABE restored robust expression of dystrophin protein to over 50% of WT levels by enabling PTC read-through in multiple muscle tissues. Importantly, systemic delivery of mxABE by AAV also rescued dystrophin expression to averages of 37%, 6%, and 54% of WT levels in the diaphragm, tibialis anterior, and heart muscle, respectively, as well as rescued muscle function. Our data strongly suggest that mxABE-based strategies may be a viable new treatment modality for DMD and other monogenic diseases.

Intravenous amino acids may mediate the adverse effect of early parenteral nutrition on mortality in critically ill patients requiring mechanical ventilation: A post hoc analysis of the NEED trial.

BACKGROUND: There is controversy regarding the optimal timing of initiating parenteral nutrition (PN) in critically ill patients. We aimed to evaluate the association between early PN and clinical outcomes and explore the mediation effects of different macronutrients in a cohort of mechanically ventilated patients. METHODS: This is a post hoc analysis of the NEED trial aiming to investigate the effect of implementing an evidence-based feeding guideline in newly-admitted critically ill patients. All eligible patients were divided into those who received early PN within the first 3 days of enrollment (early PN) or those who did not (non-early PN). Propensity score matching with a one-to-one nearest neighbor-matching algorithm was applied to control potential confounders. Mediation analysis was used to test the indirect effect of different macronutrients from PN on the relationship between early PN and 28-day mortality. RESULTS: The propensity score matching created 370 matched pairs of 1154 patients that met the eligibility criteria. Compared with non-early PN, patients receiving early PN had significantly higher 28-day mortality (19.7% vs 12.4%; hazard ratio = 1.904; 95% CI, 1.063-3.410; P = 0.03). Mediation analysis showed that amino acids from early PN mediated 65% (mediation effect = 0.07; 95% CI, 0.02-0.13; P = 0.01) of the detrimental effect of early PN on the 28-day mortality. CONCLUSION: Early PN is associated with increased 28-day mortality in critically ill patients requiring invasive mechanical ventilation. The detrimental effect may be mediated by intravenous amino acids from early PN.

Assessing multiple factors affecting the gut microbiome structure of very preterm infants

The composition and diversity of the gut microbiota are essential for the health and development of the immune system of infants. However, there is limited information on factors that influence the gut microbiota of very preterm infants. In this study, we analyzed factors that affect the gut microbiota of very preterm infants. The stool samples from 64 very preterm infants with a gestational age less than 32 weeks were collected for 16S rRNA gene sequencing. The infants were divided according to the delivery mode, antibiotic use during pregnancy, and feeding methods. The abundance of Proteobacteria was high in both cesarean (92.7%) and spontaneous (55.5%) delivery groups and then shifted to Firmicutes after the first week of birth. In addition, Proteobacteria was also the dominant phylum of infant gut microbiome for mothers with antibiotic use, with more than 50% after the first week of birth. In comparison, the dominant phylum for mothers without antibiotic use was Firmicutes. Proteobacteria level was also high in breastfeeding and mixed-feeding groups, consisting of more than 90% of the community. By contrast, Proteobacteria was the dominant phylum at the first week of birth but then shifted to Firmicutes for the formula-fed group. The alterations of gut microbiota in infants can affect their health condition during growth. This study confirmed that the different feeding types, delivery modes, and use of antibiotics during pregnancy can significantly affect the composition of the gut microbiota of very preterm infants.