Genotypic-phenotypic landscape computation based on first principle and deep learning.

The relationship between genotype and fitness is fundamental to evolution, but quantitatively mapping genotypes to fitness has remained challenging. We propose the Phenotypic-Embedding theorem (P-E theorem) that bridges genotype-phenotype through an encoder-decoder deep learning framework. Inspired by this, we proposed a more general first principle for correlating genotype-phenotype, and the P-E theorem provides a computable basis for the application of first principle. As an application example of the P-E theorem, we developed the Co-attention based Transformer model to bridge Genotype and Fitness model, a Transformer-based pre-train foundation model with downstream supervised fine-tuning that can accurately simulate the neutral evolution of viruses and predict immune escape mutations. Accordingly, following the calculation path of the P-E theorem, we accurately obtained the basic reproduction number (${R}_0$) of SARS-CoV-2 from first principles, quantitatively linked immune escape to viral fitness and plotted the genotype-fitness landscape. The theoretical system we established provides a general and interpretable method to construct genotype-phenotype landscapes, providing a new paradigm for studying theoretical and computational biology.

Targeting senescent cells to reshape the tumor microenvironment and improve anticancer efficacy.

Cancer is daunting pathology with remarkable breadth and scope, spanning genetics, epigenetics, proteomics, metalobomics and cell biology. Cellular senescence represents a stress-induced and essentially irreversible cell fate associated with aging and various age-related diseases, including malignancies. Senescent cells are characterized of morphologic alterations and metabolic reprogramming, and develop a highly active secretome termed as the senescence-associated secretory phenotype (SASP). Since the first discovery, senescence has been understood as an important barrier to tumor progression, as its induction in pre-neoplastic cells limits carcinogenesis. Paradoxically, senescent cells arising in the tumor microenvironment (TME) contribute to tumor progression, including augmented therapeutic resistance. In this article, we define typical forms of senescent cells commonly observed within the TME and how senescent cells functionally remodel their surrounding niche, affect immune responses and promote cancer evolution. Furthermore, we highlight the recently emerging pipelines of senotherapies particularly senolytics, which can selectively deplete senescent cells from affected organs in vivo and impede tumor progression by restoring therapeutic responses and securing anticancer efficacies. Together, co-targeting cancer cells and their normal but senescent counterparts in the TME holds the potential to achieve increased therapeutic benefits and restrained disease relapse in future clinical oncology.

Hydroboration and hydrosilylation of alkenes catalyzed by an unsymmetrical magnesium methyl complex.

The hydroboration and hydrosilylation of alkenes catalyzed by the unsymmetrical ß-diketiminate magnesium methyl complex [(DippXylNacnac)MgMe (THF)] (1) have been reported. When complex 1 was employed as a highly efficient catalyst in the hydroboration of various alkenes with HBpin, only the anti-Markovnikov hydroboration products were obtained in high yields and with high regioselectivities under mild reaction conditions (60 °C). To our surprise, it showed different regioselectivities in the hydrosilylation of a range of alkenes with PhSiH3. Aromatic alkene substrates afforded the corresponding branched Markovnikov hydrosilylation products in high yields and with high regioselectivities; conversely, aliphatic alkenes produced the linear anti-Markovnikov products in moderate yields. This is completely consistent with the corresponding density functional theory (DFT) calculations. In addition, the practical utility was demonstrated via scale-up reactions of boronate esters and a preliminary plausible mechanism of hydroboration and hydrosilylation have been investigated as well.

Penehyclidine hydrochloride alleviates lung ischemia-reperfusion injury by inhibiting pyroptosis.

OBJECTIVE: The aim of this research was to examine how penehyclidine hydrochloride (PHC) impacts the occurrence of pyroptosis in lung tissue cells within a rat model of lung ischemia-reperfusion injury. METHODS: Twenty-four Sprague Dawley (SD) rats, weighing 250 g to 270 g, were randomly distributed into three distinct groups as outlined below: a sham operation group (S group), a control group (C group), and a test group (PHC group). Rats in the PHC group received a preliminary intravenous injection of PHC at a dose of 3 mg/kg. At the conclusion of the experiment, lung tissue and blood samples were collected and properly stored for subsequent analysis. The levels of malondialdehyde, superoxide dismutase, and myeloperoxidase in the lung tissue, as well as IL-18 and IL-1ß in the blood serum, were assessed using an Elisa kit. Pyroptosis-related proteins, including Caspase1 p20, GSDMD-N, and NLRP3, were detected through the western blot method. Additionally, the dry-to-wet ratio (D/W) of the lung tissue and the findings from the blood gas analysis were also documented. RESULTS: In contrast to the control group, the PHC group showed enhancements in oxygenation metrics, reductions in oxidative stress and inflammatory reactions, and a decrease in lung injury. Additionally, the PHC group exhibited lowered levels of pyroptosis-associated proteins, including the N-terminal segment of gasdermin D (GSDMD-N), caspase-1p20, and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3). CONCLUSION: Pre-administration of PHC has the potential to mitigate lung ischemia-reperfusion injuries by suppressing the pyroptosis of lung tissue cells, diminishing inflammatory reactions, and enhancing lung function. The primary mechanism behind anti-pyroptotic effect of PHC appears to involve the inhibition of oxidative stress.

Determination of Flavonolignan Compositional Ratios in Silybum marianum (Milk Thistle) Extracts Using High-Performance Liquid Chromatography.

Milk thistle is one of the most popular ingredients in the liver protection products market. Silymarin is the main component of milk thistle and contains multiple isomers. There have been few studies focusing on the compositional ratios of silymarin isomers. In this study, we developed an HPLC method for the separation and quantification of silymarin isomers, thereby elucidating their compositional ratios. Through the analysis of more than 40 milk thistle extract products on the market, we found that the ratios, specifically Ratio 1 (the silybin B content to the silybin A content, SBNB/SBNA) and Ratio 2 (the sum of the contents of silybin B and isosilybin B to the sum of the contents of silybin A and isosilybin A, (SBNB + IBNB)/(SBNA + IBNA)), are highly consistent across milk thistle extracts, averaging approximately 1.58 and 1.28, respectively. Furthermore, such ratios were verified in milk thistle seed samples. This study introduces significant findings concerning the stable ratios among silymarin isomers in milk thistle extracts and seeds, thereby offering an innovative approach for quality assurance of milk thistle extracts.

Physicochemical Characterization, Antioxidant and Anticancer Activity Evaluation of an Acidic Polysaccharide from Alpinia officinarum Hance.

AHP-3a, a triple-helix acidic polysaccharide isolated from Alpinia officinarum Hance, was evaluated for its anticancer and antioxidant activities. The physicochemical properties and structure of AHP-3a were investigated through gel permeation chromatography, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. The weight-average molecular weight of AHP-3a was 484 kDa, with the molar percentages of GalA, Gal, Ara, Xyl, Rha, Glc, GlcA, and Fuc being 35.4%, 21.4%, 16.9%, 11.8%, 8.9%, 3.1%, 2.0%, and 0.5%, respectively. Based on the results of the monosaccharide composition analysis, methylation analysis, and NMR spectroscopy, the main chain of AHP-3a was presumed to consist of (1→4)-α-D-GalpA and (1→2)-α-L-Rhap residues, which is a pectic polysaccharide with homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) structural domains containing side chains. In addition, the results of the antioxidant activity assay revealed that the ability of AHP-3a to scavenge DPPH, ABTS, and OH free radicals increased with an increase in its concentration. Moreover, according to the results from the EdU, wound healing, and Transwell assays, AHP-3a can control the proliferation, migration, and invasion of HepG2 and Huh7 hepatocellular carcinoma cells without causing any damage to healthy cells. Thus, AHP-3a may be a natural antioxidant and anticancer component.

Effect of oxide interactions on chromium speciation transformation during simulated municipal solid waste incineration.

Chromium released during municipal solid waste incineration (MSWI) is toxic and carcinogenic. The removal of chromium from simulated MSWI flue gas by four sorbents (CaO, bamboo charcoal (BC), powdered activated carbon (PAC), and Al2O3) and the effects of four oxides (SiO2, Al2O3, Fe2O3, and CaO) on chromium speciation transformation were investigated. The results showed that the removal rates of total Cr by the four sorbents were Al2O3 < CaO < PAC < BC, while the removal rates of Cr(VI) by the four sorbents were Al2O3 < PAC < BC < CaO. CaO had a strong oxidizing effect on Cr(III), while BC and PAC had a better-reducing effect on Cr(VI). SiO2 was better for the reduction of Na2CrO4 and K2CrO4 above 1000°C due to its strong acidity, and the addition of CaO significantly inhibited the reduction of Cr(VI). MgCrO4 decomposed above 700°C to form MgCr2O4, and the reaction between MgCrO4 and oxides also existed in the form of a more stable trivalent spinel. Furthermore, when investigating the effect of oxides on the oxidation of Cr(III) in CrCl3, it was discovered that CaO promoted the conversion of Cr(III) to Cr(VI), while the presence of chlorine caused chromium to exist in the form of Cr(V), and increasing the content of CaO and extending the heating time facilitated the oxidation of Cr(III). In addition, silicate, aluminate, and ferrite were generated after the addition of SiO2, Al2O3, and Fe2O3, which reduced the alkalinity of CaO and had an important role in inhibiting the oxidation of Cr(III). The acidic oxides can not only promote the reduction of Cr(VI) but also have an inhibitory effect on the oxidation of Cr(III) ascribed to alkali metals/alkaline earth metals, and the proportion of acidic oxides can be increased moderately to reduce the generation of harmful substances in the hazardous solid waste heat treatment.

Transcriptome analysis reveals dysfunction of the endoplasmic reticulum protein processing in the sonic muscle of small yellow croaker (Larimichthys polyactis) following noise exposure.

Noise pollution is increasingly prevalent in aquatic ecosystems, causing detrimental effects on growth and behavior of marine fishes. The physiological responses of fish to underwater noise are poorly understood. In this study, we used RNA-sequencing (RNA-seq) to study the transcriptome of the sonic muscle in small yellow croaker (Larimichthys polyactis) after exposure to a 120 dB noise for 30 min. The behavioral experiment revealed that noise exposure resulted in accelerated tail swimming behavior at the beginning of the exposure period, followed by loss of balance at the end of experiment. Transcriptomic analysis found that most highly expressed genes in the sonic muscle, including parvalbumin, slc25a4, and troponin C were related with energy metabolism and locomotor function. Further, a total of 1261 differentially expressed genes (DEGs) were identified, including 284 up-regulated and 977 down-regulated genes in the noise exposure group compared with the control group. Gene ontology (GO) analysis indicated that the most enriched categories of DEGs included protein folding and response to unfolding protein. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis found over-represented pathways including protein processing in the endoplasmic reticulum, chaperones and folding catalysts, as well as arginine and proline metabolism. Specifically, many genes related to fatty acid and collagen metabolism were up-regulated in the noise exposure group. Taken together, our results indicate that exposure to noise stressors alters the swimming behavior of croaker, inducing endoplasmic reticulum stress, disrupting lipid metabolism, and causing collagen degradation in the sonic muscle of L. polyactis.

Recruitment Patterns and Environmental Sensitivity of Glass Eels of Anguilla japonica in the Yangtze Estuary, China.

The decline of Japanese eel (Anguilla japonica) populations in the Yangtze River estuary represents a critical conservation concern. Eleven-years of daily catch data during recruitment periods (i.e., January-April, 2012-2022) indicate that annual catch averaged from 153 to 1108 eels, and show a bimodal pattern in glass eel arrivals. Utilizing seasonal-trend decomposition and generalized additive models, we demonstrated a strong correlation between catch abundance, optimal water temperatures, and lunar cycles. An auto-regressive integrated moving average (ARIMA) model predicts an increase in glass eel numbers for 2023-2024 but also points to a concerning trend of delayed recruitment timing since 2016, attributable to the 0.48 °C per decade rise in sea surface temperatures. This delay correlates with a significant decrease in the average body weight of glass eels, suggesting potential energy deficits that may hinder successful upstream migration. This study not only furthers our understanding of glass eel recruitment dynamics but also underscores the urgent need for targeted conservation measures. Additionally, it highlights the importance of sustained, detailed monitoring to mitigate the detrimental effects of climate change on these eels, vital for preserving the Yangtze River's ecological integrity.

Effects of plant community structural characteristics on carbon sequestration in urban green spaces.

The structural characteristics of plant communities in urban green spaces have a significant impact on their carbon sequestration function. In this study, comprehensive data were collected from 106 plant communities (each 20 m × 20 m) in Zhengzhou Green Expo Park. We assessed aboveground and soil carbon storage, alongside maintenance carbon emissions, to quantify carbon dynamics. Our primary objective was to establish a statistical model that correlates the structural attributes of plant communities with their total annual carbon sequestration. This model aims to provide a quantitative framework for optimizing community structures to maximize carbon sequestration in urban green spaces. The results showed that density and coverage were significantly and positively correlated with aboveground and soil carbon stocks. Density and mean height were significantly and positively correlated with maintenance carbon emissions. Density played a key structural role in regulating the total carbon sequestration of the plant communities, being 27.24 times more effective than coverage. The total annual carbon sequestration of the plant community reached an optimal value of 327.67 kg CO2-eq/y-1 at a density and cover of 0.15 and 1, respectively. This study provides valuable data for increasing the carbon sink ability of urban green spaces through plant structure regulation and supporting low-carbon development strategies in urban management.

Kaempferol from Alpinia officinarum hance induces G2/M cell cycle arrest in hepatocellular carcinoma cells by regulating the ATM/CHEK2/KNL1 pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Alpinia officinarum Hance (A. officinarum), a perennial herb known for its medicinal properties, has been used to treat various ailments, such as stomach pain, abdominal pain, emesis, and digestive system cancers. A. officinarum is extensively cultivated in the Qiongzhong and Baisha regions of Hainan, and it holds substantial therapeutic value for the local Li people of Hainan. Kaempferol, a flavonoid derived from A. officinarum, has demonstrated anticancer properties in various experimental and biological studies. Nevertheless, the precise mechanisms through which it exerts its anti-hepatocellular carcinoma (HCC) effects remain to be comprehensively delineated. AIM OF THE STUDY: This investigation aims to elucidate the anti-HCC effects of kaempferol derived from A. officinarum and to delve into its underlying mechanistic pathways. MATERIALS AND METHODS: Using ultra-high performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS/MS) to identify active compounds in A. officinarum. HCCLM3 and Huh7 cells were used to study the anti-HCC effect of kaempferol from A. officinarum. The cytotoxicity and proliferation of kaempferol and A. officinarum were measured using CCK-8 and EDU staining. Wound-healing assays and three-dimensional tumor spheroid models were further used to evaluate migration and the anti-HCC activity of kaempferol. The cell cycle and apoptosis were evaluated by flow cytometry. Western blot and qRT-PCR were used to detect the expression of proteins and genes associated with the cell cycle checkpoints. Finally, bioinformatics was used to analyze the relationship between the differential expression of core targets in the ATM/CHEK2/KNL1 pathway and a poor prognosis in clinical HCC samples. RESULTS: UPLC-MS/MS was employed to detect five active compounds in A. officinarum, such as kaempferol. The CCK-8 and EDU assays showed that kaempferol and A. officinarum significantly inhibited the proliferation of HCC cells. A wound-healing assay revealed that kaempferol remarkably inhibited the migration of HCC cells. Kaempferol significantly suppressed the growth of tumor spheroids. In addition, kaempferol markedly induced G2/M arrest and promoted apoptosis of HCC cells. Mechanically, kaempferol significantly reduced the protein and mRNA expression levels of ATM, CHEK2, CDC25C, CDK1, CCNB1, MPS1, KNL1, and Bub1. Additionally, the combination of kaempferol and the ATM inhibitor KU55933 had a more significant anti-HCC effect. The results of bioinformatics showed that ATM, CHEK2, CDC25C, CDK1, and KNL1 were highly expressed in patients with HCC and cancer tissues, indicating that these genes have certain value in the clinical diagnosis of HCC. CONCLUSIONS: Collectively, our results revealed that kaempferol from A. officinarum inhibits the cell cycle by regulating the ATM/CHEK2/KNL1 pathway in HCC cells. In summary, our research presents an innovative supplementary strategy for HCC treatment.

Whole transcriptome sequencing reveals key genes and ceRNA regulatory networks associated with pimpled eggs in hens.

Eggshell is one of the most important indicators of egg quality, and due to low shell strength, pimple eggs (PE) are more susceptible to breakage, thus causing huge economic losses to the egg industry. At the current time, the molecular mechanisms that regulate the formation of pimple eggs are poorly understood. In this study, uterine tissues of PE-laying hens (n = 8) and normal egg (NE) -laying hens (n = 8) were analyzed by whole transcriptome sequencing, and a total of 619 differentially expressed mRNAs (DE mRNAs), 122 differentially expressed lncRNAs (DE lncRNAs) and 21 differentially expressed miRNAs (DE miRNAs) were obtained. Based on the targeting relationship among DE mRNAs, DE lncRNAs and DE miRNAs, we constructed a competitive endogenous RNA (ceRNA) network including 12 DE miRNAs, 19 DE lncRNAs, and 128 DE mRNAs. Considering the large amount of information contained in the network, we constructed a smaller ceRNA network to better understand the complex mechanisms of pimple egg formation. The smaller ceRNA network network contains 7 DE lncRNAs (LOC107056551, LOC121109367, LOC121108909, LOC121108862, LOC112530033, LOC121113165, LOC107054145), 5 DE miRNAs (gga-miR-6568-3p, gga-miR-31-5p, gga-miR-18b-3p, gga-miR-1759-3p, gga-miR-12240-3p) and 7 DE mRNAs (CABP1, DNAJC5, HCN3, HPCA, IBSP, KCNT1, OTOP3), and these differentially expressed genes may play key regulatory roles in the formation of pimpled eggs in hens. This study provides the overall expression profiles of mRNAs, lncRNAs and miRNAs in the uterine tissues of hens, which provides a theoretical basis for further research on the molecular mechanisms of pimpled egg formation, and has potential applications in improving eggshell quality.

Ferritin-mediated mitochondrial iron homeostasis is essential for the survival of hematopoietic stem cells and leukemic stem cells.

Iron metabolism plays a crucial role in cell viability, but its relationship with adult stem cells and cancer stem cells is not fully understood. The ferritin complex, responsible for intracellular iron storage, is important in this process. We report that conditional deletion of ferritin heavy chain 1 (Fth1) in the hematopoietic system reduced the number and repopulation capacity of hematopoietic stem cells (HSCs). These effects were associated with a decrease in cellular iron level, leading to impaired mitochondrial function and the initiation of apoptosis. Iron supplementation, antioxidant, and apoptosis inhibitors reversed the reduced cell viability of Fth1-deleted hematopoietic stem and progenitor cells (HSPCs). Importantly, leukemic stem cells (LSCs) derived from MLL-AF9-induced acute myeloid leukemia (AML) mice exhibited reduced Fth1 expression, rendering them more susceptible to apoptosis induced by the iron chelation compared to normal HSPCs. Modulating FTH1 expression using mono-methyl fumarate increased LSCs resistance to iron chelator-induced apoptosis. Additionally, iron supplementation, antioxidant, and apoptosis inhibitors protected LSCs from iron chelator-induced cell death. Fth1 deletion also extended the survival of AML mice. These findings unveil a novel mechanism by which ferritin-mediated iron homeostasis regulates the survival of both HSCs and LSCs, suggesting potential therapeutic strategies for blood cancer with iron dysregulation.

Sialic acid-based probiotic intervention in lactating mothers improves the neonatal gut microbiota and immune responses by regulating sialylated milk oligosaccharide synthesis via the gut-breast axis.

Human milk oligosaccharides (HMOs) are vital milk carbohydrates that help promote the microbiota-dependent growth and immunity of infants. Sialic acid (SA) is a crucial component of sialylated milk oligosaccharides (S-MOs); however, the effects of SA supplementation in lactating mothers on S-MO biosynthesis and their breastfed infants are unknown. Probiotic intervention during pregnancy or lactation demonstrates promise for modulating the milk glycobiome. Here, we evaluated whether SA and a probiotic (Pro) mixture could increase S-MO synthesis in lactating mothers and promote the microbiota development of their breastfed neonates. The results showed that SA+Pro intervention modulated the gut microbiota and 6'-SL contents in milk of maternal rats more than the SA intervention, which promoted Lactobacillus reuteri colonization in neonates and immune development. Deficient 6'-SL in the maternal rat milk of St6gal1 knockouts (St6gal1-/-) disturbed intestinal microbial structures in their offspring, thereby impeding immune tolerance development. SA+Pro intervention in lactating St6gal1± rats compromised the allergic responses of neonates by promoting 6'-SL synthesis and the neonatal gut microbiota. Our findings from human mammary epithelial cells (MCF-10A) indicated that the GPR41-PI3K-Akt-PPAR pathway helped regulate 6'-SL synthesis in mammary glands after SA+Pro intervention through the gut - breast axis. We further validated our findings using a human-cohort study, confirming that providing SA+Pro to lactating Chinese mothers increased S-MO contents in their breast milk and promoted gut Bifidobacterium spp. and Lactobacillus spp. colonization in infants, which may help enhance immune responses. Collectively, our findings may help alter the routine supplementation practices of lactating mothers to modulate milk HMOs and promote the development of early-life gut microbiota and immunity.

Sphingosine d18:1 promotes nonalcoholic steatohepatitis by inhibiting macrophage HIF-2α.

Non-alcoholic steatohepatitis (NASH) is a severe type of the non-alcoholic fatty liver disease (NAFLD). NASH is a growing global health concern due to its increasing morbidity, lack of well-defined biomarkers and lack of clinically effective treatments. Using metabolomic analysis, the most significantly changed active lipid sphingosine d18:1 [So(d18:1)] is selected from NASH patients. So(d18:1) inhibits macrophage HIF-2α as a direct inhibitor and promotes the inflammatory factors secretion. Male macrophage-specific HIF-2α knockout and overexpression mice verified the protective effect of HIF-2α on NASH progression. Importantly, the HIF-2α stabilizer FG-4592 alleviates liver inflammation and fibrosis in NASH, which indicated that macrophage HIF-2α is a potential drug target for NASH treatment. Overall, this study confirms that So(d18:1) promotes NASH and clarifies that So(d18:1) inhibits the transcriptional activity of HIF-2α in liver macrophages by suppressing the interaction of HIF-2α with ARNT, suggesting that macrophage HIF-2α may be a potential target for the treatment of NASH.

A microbial metabolite inhibits the HIF-2α-ceramide pathway to mediate the beneficial effects of time-restricted feeding on MASH.

Time-restricted feeding (TRF) is a potent dietary intervention for improving metabolic diseases, including metabolic dysfunction-associated steatotic liver disease/metabolic dysfunction-associated steatohepatitis (MASLD/MASH). However, the mechanism of this efficacy has remained elusive. Here, we show that TRF improves MASLD, which is associated with a significant enrichment of Ruminococcus torques (R. torques). Mechanistically, R. torques suppresses the intestinal HIF-2α-ceramide pathway via the production of 2-hydroxy-4-methylpentanoic acid (HMP). We identify rtMor as a 4-methyl-2-oxopentanoate reductase that synthesizes HMP in R. torques. Finally, we show that either the colonization of R. torques or oral HMP supplementation can ameliorate inflammation and fibrosis in a MASH mouse model. These findings identify R. torques and HMP as potential TRF mimetics for the treatment of metabolic disorders.

Recurrent respiratory tract infections in children might be associated with vitamin A status: a case-control study.

Background: Recurrent respiratory tract infections (RRTIs) are common in children and its development might be associated with vitamin A deficiency according to recent research. The aim of this study was to understand the relation between vitamin A status and RRTIs in children, and the relation between dietary intake of vitamin A and RRTIs. Methods: 2,592 children aged 0.5-14 years from Heilongjiang province of China participated in the survey. The RRTI group consisted of 1,039 children with RRTIs, while 1,553 healthy children were included in the control group. The levels of serum vitamin A were determined by high performance liquid chromatography (HPLC); dietary information was collected with the Food Frequency Questionnaire (FFQ). Results: Serum vitamin A concentration in the RRTI group was significantly lower than that in the control group (0.27 ± 0.09 mg/L vs. 0.29 ± 0.09 mg/L) (P < 0.01). The levels of vitamin A was obviously associated with the occurrence of RRTIs. The odds ratios (ORs) for vitamin A insufficiency and deficiency were 1.32 (95% CI: 1.09-1.60) and 1.95 (95% CI: 1.50-2.55) respectively; whereas 1.48 (95% CI: 1.13-1.94) and 6.51 (95% CI: 4.18-10.14) respectively, in children with current respiratory tract infection (RTI) symptoms. Even an insufficient intake of animal liver was associated with lower RRTIs [OR: 0.45 (95% CI: 0.38-0.53)], while only an excessive intake of meat had the same effect [OR: 0.85 (95% CI: 0.68-1.06)]. Conclusions: Low serum vitamin A concentration was associated with high incidence of RRTIs in children in northeast China; low serum vitamin A concentrations and the current RTI symptoms were associated with the development of RRTIs; and low intakes of vitamin A-rich foods were also associated with the development of RRTIs.