Following the improvement of survival rate of very premature infants，the incidence of bronchopulmonary dysplasia（BPD）has been showing a rising trend in recent years.BPD is the most common and severe pulmonary complication in premature infants.Although prematurity and immature pulmonary growth are the most important risk factors in the development of BPD，the precise pathogenesis of BPD remains to be verified.Silent information regulator 2 homolog 1（SIRT1）belongs to sirtuin family，which plays an important role in the progress of inflammation，oxidative stress，apoptosis，autophagy and epithelial-mesenchymal transition，which is closely associated with BPD.Current studies of SIRT1 in the mechanism of BPD are reviewed in this article，which may provide reference for pathogenesis of BPD and potential therapeutic target.

Autism spectrum disorder（ASD）is a neurodevelopmental disorder characterized by social disorders and restricted，repetitive stereotyped behaviors.The pathogenesis of ASD is not clear.There are no recognized drugs that could be used to improve the core symptoms of ASD.Drug treatment is mainly aimed at their emotional problems and inappropriate behavior.Atypical second-generation antipsychotic drugs such as risperidone and aripiprazole are commonly used to deal with the emotional and behavioral problems of children with ASD.Comorbidities such as attention deficit hyperactivity disorder，epilepsy，gastrointestinal symptoms and sleep disorder are common in children with ASD.Methylphenidate and atomoxetine are the first choice for the treatment of ASD with attention deficit hyperactivity disorder.At present，there are still some drugs that have not been widely used in clinical practice，and need further support from evidence-based medicine.

Infliximab（IFX）is one of anti-tumor necrosis factor-α（anti-TNF-α）and is currently biological preparations with indications for the use of inflammatory bowel disease（IBD）of children in China.With the clinical application of IFX，the treatment goal of IBD has shifted from clinical remission to mucosal healing，thereby further improving the prognosis of the disease.However，in clinical work，it has been found that some children have primary or secondary unresponsiveness to IFX treatment，which is a major challenge during the IFX treatment process.Research has found that this phenomenon may be related to a decrease in blood drug concentration and the production of anti drug antibodies.Therefore，IFX therapeutic drug monitoring（TDM）is very important in the treatment of pediatric IBD.This article reviews the current application status of TDM in the treatment of IBD in children with IFX，and puts forward prospects for future research directions of TDM.

Munchausen syndrome by proxy（MSBP）in children refers to the caregivers who enforce unnecessary medication-seeking on children by falsifying symptoms or inducing disease（exacerbation），resulting in different degrees of physical or mental damage.And it may lead to adverse psychosocial consequences of the victims in adulthood，and even become the new "MSBP caregivers".First reported in 1977，MSBP in children has attracted widespread attention in European and American countries，and gradually attracted attention worldwide.However，Chinese pediatricians have insufficient knowledge of the disease at present，and there are just a few relevant literature reports in China.This article reviews the clinical features and progress on diagnosis and treatment of MSBP in children.

Infliximab is one of the most extensively used biological agents in the treatment of Crohn's disease，but in the actual application process，some patients may have loss of response，which may lead to the refactory disease and the rise of treatment cost.Identifying loss of response at an early phase has become a crucial component of treatment，but the academic community has not a unified prediction standard yet.This article reviews the recent indicators for predicting loss of response to infliximab treatment，such as infliximab concentration and anti-antibody monitoring，serological indicators，ultrasound，magnetic resonance imaging and endoscopy，clinical indicators of Crohn's disease，HLA-DQA1*05 gene，newly developed models and indicators and their criteria.

Long-COVID-19 syndrome（LCS）is a multisystem and chronic disease caused by SARS-CoV-2，which can be attributed to the disorder of gut microbiota.Compared to healthy individuals，patients with LCS have different microbial communities，which can last for some time.The distribution of gut microbiota is different.Potential mechanisms that affect LCS may be related to gut-lung axis，gut-brain axis，potential pathogenic bacterias，microbial metabolites，etc.Prevention and treatment about LCS based on gut microbiota mainly contain probiotics，prebiotics，fecal microbiota transplantation，etc.Clarifying the relationship and pathogenesis between gut microbiota and LCS may contribute to early diagnosis and the research for new biological targets.

Maintaining the homeostasis of gut microbes is essential for the maintenance of human health.The evolution of the human gut microbiota is involved in many physiological functions.Besides，changes in gut flora can be traced back to early life.The prevalence of malnutrition in infants and young children is persistently high，especially in low-and middle-income countries.More and more researches have confirmed that the immature development of intestinal microbiota and abnormal metabolites are related to malnutrition.Due to nutritional diet is the most important factor affecting the microbiota，studies have begun to assess the therapeutic potential of microbiota oriented food interventions in improving infant and young child malnutrition.Therefore，this review summarizes the latest advances in the field and recommend further progress towards finding new treatments for the malnutrition of infant and young child.

Ulcerative colitis（UC）presents as a chronic，non-specific intestinal inflammatory disease with an obscure etiology and pathogenesis.Early clinical manifestations in pediatric patients lack specificity，necessitating reliance on endoscopic of invasive examination，which is poorly tolerated，particularly by infants and toddlers.This review summarizes advancements in non-invasive diagnostic examinations for pediatric UC，emphasizing their value in early detection.Non-invasive imaging modalities，including intestinal ultrasound，CT enterography，and magnetic resonance enterography，can improve children acceptance.Serum autoantibodies，fecal calprotectin，non-coding RNA and other biomarkers also have potential application value for early clinical diagnosis.In addition，recent studies in intestinal microbiota and metabolomics analysis also hold promise for applying to early diagnosis in pediatric UC.

Acute kidney injury（AKI）is one of the risk factors leading to death in premature infants.The incidence of AKI showed a upward trend year by year.The pathogenesis may be related to preterm birth with insufficient nephrons，prenatal inflammatory injury and urinary podocyte loss.The occurrence rate of AKI in premature infants increased with the decreasing of gestational age and birth weight.It should be emphasized that AKI in premature infants does not exist independently，but interacts with other organs，such as heart，lung，intestine，brain，and other organs.Moreover，the involvement of these organs may increase the risk of AKI，and so does bloodstream infections.Blood creatinine and urine volume can be used for clinical diagnosis and classification of AKI in premature infants.Glucocorticoids and caffeine can protect kidney in premature infants.Due to the lack of specificity in the treatment of AKI，fluid management and medication are important for the development of AKI.Renal replacement therapy，the common of which are peritoneal dialysis and continuous renal replacement therapy，can be used in severe AKI.

Children's sleep health runs through the entire process of children's growth and development and is of great significance.Sleep disorders are one of the important problems affecting children's grow，development and growth health.The number of pediatric patients with sleep disorders is on the rise year by year.Current studies show that the disturbance of children's sleep homeostasis is usually accompanied by the increase of neuroendocrine system activities，the activation of immune system，metabolic disorders，etc，lead to the corresponding hormones（such as cortisol），inflammatory factors，metabolic substances and other homeostasis changes，mutual influence，forming a vicious cycle.In addition，the relationship between genetic factors and sleep is also increasingly concerned.This article reviews the mechanisms，influencing factors and research progress of children's sleep health and sleep disorders，aiming to provide a reference for clinical intervention in children′s sleep problems.