1.Differentiation and treatment strategies for ulcerative colitis based on the"midnight-noon and ebb-flow"theory
Lingfei MENG ; Chaolun ZHU ; Zixu ZHAO ; Ranran SONG ; Yifan WANG ; Congling FAN ; Liuyue MI ; Shuangxi zhang
Journal of Beijing University of Traditional Chinese Medicine 2026;49(1):16-23
Ulcerative colitis is a chronic relapsing inflammatory bowel disease. Modern research indicates that immune dysregulation resulting from disruptions in circadian rhythm is closely associated with its pathogenesis. Both Western chronomedicine and traditional Chinese medicine(TCM)" treatment based on temporal factors" emphasize the temporal relationship between natural rhythms and human physiology and pathology. The " midnight-noon and ebb-flow " theory represents the concrete application and deepening of TCM " treatment based on temporal factors" within the realm of chronomedicine. This article correlates the onset time of ulcerative colitis with specific periods in the " midnight-noon and ebb-flow"theory:the Mao period(05:00-07:00),when the yangming large intestine meridian of hand is dominant; the Si period(09:00-11:00),when the taiyin spleen meridian of foot is dominant; and the You period(17:00-19:00),when the shaoyin kidney meridian of foot is dominant. According to this perspective,if the disease manifests during the Mao period,the pathogenesis is attributed to dampnessheat accumulation and disorder of qi and blood. Treatment should focus on clearing heat,resolving dampness,and harmonizing qi and blood,using modified formulas such as Shaoyao Decoction or Baitouweng Decoction. If it occurs during the Si period,the pathogenesis involves spleen deficiency with dampness obstruction and disharmony of qi and blood. Treatment should focus on strengthening the spleen,eliminating dampness,and restoring qi and blood,using modified formulas such as Huangya Decoction or Shenling Baizhu Powder. If it presents during the You period,the pathogenesis is characterized by fire failing to warm earth,and consumption resulting in qi and blood leakage. Treatment should focus on warming the kidney and spleen,and securing qi and blood,using modified formulas such as Sishen Pill or Tianhun Decoction. In addition to oral administration of Chinese herbal medicine,comprehensive therapies including acupuncture,herbal enemas,and acupoint application can provide novel insights for the clinical diagnosis and treatment of ulcerative colitis.
2.High-altitude exposure on retinal damage and oxidative stress levels
Quan ZHAO ; Song WANG ; Chen YIN ; Meng JING ; Juan MA ; Yan CAI
International Eye Science 2026;26(5):760-766
AIM:To investigate the effects of high-altitude hypoxic exposure on retinal injury and the associated changes in oxidative stress-related indicators in rats. METHODS: Twenty-four healthy male Sprague-Dawley(SD)rats were randomly divided into a plain group and a high-altitude group, with 12 rats(24 eyes)in each group. Rats in the plain group were housed under normoxic conditions in an SPF-grade animal facility, whereas rats in the high-altitude group were placed in a special environmental chamber simulating an altitude of 6 000 m for 7 d. Optical coherence tomography(OCT)was used to assess retinal layer architecture and quantify retinal thickness. Hematoxylin-eosin(HE)staining was performed to observe retinal histopathological changes. Immunofluorescence(IF)was used to detect the expression of hypoxia-inducible factor-1α(HIF-1α)in retinal tissue. Transmission electron microscopy(TEM)was applied to examine the ultrastructure of retinal ganglion cells(RGCs). Enzyme-linked immunosorbent assay(ELISA)was used to measure the levels of malondialdehyde(MDA), total superoxide dismutase(T-SOD), and reduced glutathione(GSH)in retinal tissue. In addition, intracellular reactive oxygen species(ROS)levels in retinal tissue were assessed using the 2',7'-dichlorodihydrofluorescein diacetate(DCFH-DA)fluorescent probe. RESULTS: OCT examination revealed disorganized retinal architecture in the high-altitude group, with increased inner and middle ring thickness and decreased outer ring thickness compared with the plain group(all P<0.05). HE staining showed varying degrees of retinal layer damage, blurred layer boundaries, loosely arranged RGCs, and partial cellular necrosis in the high-altitude group. IF analysis demonstrated significantly increased HIF-1α expression in the inner nuclear layer of the high-altitude group(P<0.01). TEM revealed mitochondrial swelling, disrupted cristae, and reduced matrix electron density in RGCs of the high-altitude group. ELISA and fluorescence probe assays showed significantly elevated MDA levels and ROS fluorescence intensity, accompanied by decreased T-SOD and GSH levels in the retinal tissue of the high-altitude group(all P<0.05). CONCLUSION: Exposure to a high-altitude hypoxic environment induces marked morphological and ultrastructural damage in the rat retina and significantly enhances oxidative stress, suggesting that oxidative stress may play a critical role in retinal injury induced by high-altitude hypoxia.
3.Herbal textual research on food and medicinal homologous of Kui
Qian PAN ; Xiangqing MENG ; Yitong SONG ; Tianmengda WU ; Dan JIA ; Min JIA
Journal of Pharmaceutical Practice and Service 2026;44(4):185-188
Kui was first recorded in The Rites of Zhou and is the earliest domesticated wild vegetable in China. In the Qi Min Yao Shu, Kui was called “the master of all vegetables” and has a long history of application in China. As a medicine, Kuizi was first recorded in Shen Nong’s Herbal Classic, which has a history of more than 2 000 years of medicinal use and a long history of clinical application. By researching the ancient and modern herbal literature, the first herbs texts of Kui were examined, various recorded texts, confused products and the history of the original medicinal use were clarified. It was concluded that the ancient herbal texts recorded the base plant of Kui as Malva verticillata L. belonging to family Malvaceae, which provided scientific basis for the development and utilization of Kui.
4.Genetic analysis and prenatal diagnosis of structural brain abnormalities associated with TUBB gene c.155A>G variant.
Yifan LIU ; Wei SONG ; Xinlian WANG ; Yan RUAN ; Meng ZHANG ; Yujiao CHEN ; Yan LIU ; Puqing ZHANG ; Li WANG ; Yousheng YAN
Chinese Journal of Medical Genetics 2026;43(2):136-142
OBJECTIVE:
To explore the genotype-phenotype correlation in a Chinese family with structural brain abnormalities due to variant of the TUBB gene.
METHODS:
A family undergoing prenatal diagnosis at Beijing Obstetrics and Gynecology Hospital in October 2024 was selected as the study subject. Clinical data were collected. Amniotic fluid sample was subjected to chromosomal copy number variation sequencing (CNV-seq). Trio whole-exome sequencing (Trio-WES) was carried out on the amniotic fluid and parental blood samples, and candidate variant was verified by Sanger sequencing. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 2023-KY-076-01).
RESULTS:
Both prenatal ultrasound and fetal MRI showed deviation of brain midline, unilateral lateral ventriculomegaly, and bilateral gyral asymmetry. Trio-WES revealed that the fetus has harbored a maternally derived heterozygous missense variant of the TUBB gene [NM_178014.4: c.155A>G (p.N52S)]. Sanger sequencing confirmed that the woman and a previously terminated fetus both harbored the same variant. Both the proband and two fetuses exhibited similar neuroimaging abnormalities including midline deviation and asymmetrical gyri. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as likely pathogenic (PM2_Supporting+PS2_Moderate+PS3).
CONCLUSION
The heterozygous c.155A>G (p.N52S) variant was the TUBB gene probably underlay the pathogenesis of the structural brain abnormalities in this family. Above findings have expanded the phenotypic spectrum associated with the variant and facilitated the prenatal diagnosis for this family.
Humans
;
Female
;
Pregnancy
;
Prenatal Diagnosis
;
Tubulin/genetics*
;
Adult
;
Brain/diagnostic imaging*
;
Male
;
Pedigree
;
DNA Copy Number Variations/genetics*
;
Exome Sequencing
;
Genetic Association Studies
;
Magnetic Resonance Imaging
5.Effect of mussel-derived antimicrobial peptide-coated modified prosthesis on prevention of early periprosthetic joint infection and regulation of bone transfer
Bo LIU ; WUHUZI·WULAMU ; Guangzhao ZHU ; Xiaobin GUO ; Ziyue SONG ; Xingbu MENG ; Junjie HU ; Xiaogang ZHANG
Chinese Journal of Tissue Engineering Research 2026;30(2):278-287
BACKGROUND:Periprosthetic joint infection is the most common cause of early failure after total knee replacement.The current methods of preventing periprosthetic joint infection by improving the surface of the prosthesis have limitations to varying degrees.OBJECTIVE:To construct a coating material that can stably improve the surface of the implant,prevent the initial floating bacterial infection of periprosthetic infection,and regulate the bone transfer function around the implant.METHODS:(1)Material preparation:YGF polypeptide(which promotes bone formation),LL-37 polypeptide(with antibacterial properties)and YGF+LL-37 composite peptide were prepared by Fmoc solid phase peptide synthesis technology.The titanium-based materials were immersed in the three polypeptide solutions for 2 hours to obtain YGF coating,LL-37 coating and composite peptide coating coated titanium sheets.(2)In vitro experiment:Uncoated titanium sheets and coated titanium sheets were co-cultured with Escherichia coli(or Staphylococcus aureus)and the colonies were counted by plate method.MC3T3 cells were inoculated on the surface of uncoated titanium sheet and coated titanium sheet,respectively.Alizarin red staining was used to observe the calcium salt deposition on the surface of the material.Western blot assay was used to detect the protein expression of RUNX2,osteocalcin,osteopontin,and bone morphogenetic protein 2.(3)Animal experiment:24 SD rats were randomly divided into three groups:the blank group(n=8)was implanted with uncoated titanium nails in the femoral medullary canal;the control group(n=8)was implanted with uncoated titanium nails in the femoral medullary canal+intra-articular injection of Staphylococcus aureus suspension;the experimental group(n=8)was implanted with composite peptide coated titanium nails in the femoral medullary canal+intra-articular injection of Staphylococcus aureus suspension.After 5 weeks of implantation,micro-CT examination,hematoxylin-eosin staining and immunohistochemical staining of femur specimens were performed.RESULTS AND CONCLUSION:(1)In vitro experiment:Compared with uncoated titanium sheet and YGF coated titanium sheet,LL-37 coated and composite peptide coated titanium sheet could significantly inhibit the growth and reproduction of Escherichia coli and Staphylococcus aureus.Compared with uncoated titanium sheets and LL-37-coated titanium sheets,YGF-coated and composite peptide-coated titanium sheets could promote calcium salt deposition in osteoblasts and increase the protein expression of RUNX2,osteocalcin,osteopontin and bone morphogenetic protein 2.(2)Animal experiment:Micro-CT test showed that the control group had less bone mass than the blank group and the experimental group.Hematoxylin-eosin staining showed that there was a large amount of fibrous tissue around the nail channel in the control group,only a small amount of tissue fibrosis around the nail channel in the blank group,and only a small amount of tissue fibrosis around the nail channel in the experimental group.Immunohistochemical staining showed that the protein expression of interleukin 1β and tumor necrosis factor α in the control group was higher than that in the blank group and the experimental group,and the expression of osteocalcin,RUNX2 and osteopontin in the experimental group was higher than that in the blank group and the control group.(3)The results show that the titanium-based material coated with YGF+LL-37 composite peptide coating has good antibacterial ability and can promote bone transfer around the implant.
6.Effects of long-term endurance exercise on kl/FGF23 axis and calcium-phosphorus metabolism in naturally aging mice
Tuanhui PENG ; Hongming SONG ; Ling YANG ; Xiaoge DING ; Pengjun MENG
Chinese Journal of Tissue Engineering Research 2026;30(5):1089-1095
BACKGROUND:Studies have shown that disorders of mineral metabolism may be responsible for premature aging and that the kl/FGF23 axis plays an important role in mineral metabolism.OBJECTIVE:To explore the effect of long-term endurance exercise on the kl/FGF23 axis in naturally aging mice,and to observe the impact of long-term endurance exercise on calcium and phosphorus metabolism,so as to provide a reference for the influence of long-term endurance exercise on natural aging.METHODS:Twenty-two 5-week-old SPF male balb/c mice were randomly divided into three groups:young and quiet control group,natural aging quiet group and natural aging exercise group.Mice in the young and quiet control group were then killed immediately.Mice in the natural aging quiet group were raised normally until 60 weeks of age.Mice in the natural aging exercise group were subjected to adaptive exercise for 1 week,followed by the maximum running speed test.The official exercise speed was set at 70%of the maximum running speed,and exercise was performed on Mondays,Wednesdays,and Fridays for 50 minutes each.Maximum running speed was retested at 8-week intervals to adjust the official exercise speed until the age of 60 weeks.(3)Enzyme-linked immunoassay was used to measure the levels of femoral fibroblast growth factor 23,renal fibroblast growth factor receptor 1,1α-hydroxylase,and serum 1,25(OH)2D3.RESULTS AND CONCLUSION:(1)Compared with the young and quiet control group,serum calcium and phosphorus levels in natural aging quiet group had no significant changes(P>0.05),but bone calcium and phosphorus levels were significantly reduced(P<0.01).Compared with the natural aging quiet group,the serum phosphorus level was significantly reduced(P<0.05),the serum calcium level did not change(P>0.05),and bone calcium and phosphorus levels were significantly increased in the natural aging exercise group(P<0.05).(2)Compared with the young and quiet control group,the level of fibroblast growth factor 23 in the femur of the natural aging quiet group was significantly increased(P<0.05).Compared with the natural aging quiet group,the level of fibroblast growth factor 23 in the femur of the natural aging exercise group was reduced,but it was not statistically significant(P>0.05).(3)Compared with the young and quiet control group,the renal Klotho protein expression,the renal fibroblast growth factor receptor 1,1α-hydroxylase,and serum 1,25(OH)2 D3 levels in the natural aging quiet group were significantly decreased(P<0.05,P<0.01).Compared with the natural aging quiet group,the levels of the above-mentioned indicators were significantly increased in the natural aging exercise group(P<0.05,P<0.01).To conclude,long-term endurance exercise can regulate Klotho protein and fibroblast growth factor 23 through the kl/FGF23 axis,thereby affecting the expression of 1α-hydroxylase and the level of 1,25(OH)2D3,and further regulating the body's calcium and phosphorus metabolism,especially phosphate metabolism.This indicates that long-term endurance exercise can delay the natural aging of the body through the kl/FGF23 axis.
7.Effect of mussel-derived antimicrobial peptide-coated modified prosthesis on prevention of early periprosthetic joint infection and regulation of bone transfer
Bo LIU ; WUHUZI·WULAMU ; Guangzhao ZHU ; Xiaobin GUO ; Ziyue SONG ; Xingbu MENG ; Junjie HU ; Xiaogang ZHANG
Chinese Journal of Tissue Engineering Research 2026;30(2):278-287
BACKGROUND:Periprosthetic joint infection is the most common cause of early failure after total knee replacement.The current methods of preventing periprosthetic joint infection by improving the surface of the prosthesis have limitations to varying degrees.OBJECTIVE:To construct a coating material that can stably improve the surface of the implant,prevent the initial floating bacterial infection of periprosthetic infection,and regulate the bone transfer function around the implant.METHODS:(1)Material preparation:YGF polypeptide(which promotes bone formation),LL-37 polypeptide(with antibacterial properties)and YGF+LL-37 composite peptide were prepared by Fmoc solid phase peptide synthesis technology.The titanium-based materials were immersed in the three polypeptide solutions for 2 hours to obtain YGF coating,LL-37 coating and composite peptide coating coated titanium sheets.(2)In vitro experiment:Uncoated titanium sheets and coated titanium sheets were co-cultured with Escherichia coli(or Staphylococcus aureus)and the colonies were counted by plate method.MC3T3 cells were inoculated on the surface of uncoated titanium sheet and coated titanium sheet,respectively.Alizarin red staining was used to observe the calcium salt deposition on the surface of the material.Western blot assay was used to detect the protein expression of RUNX2,osteocalcin,osteopontin,and bone morphogenetic protein 2.(3)Animal experiment:24 SD rats were randomly divided into three groups:the blank group(n=8)was implanted with uncoated titanium nails in the femoral medullary canal;the control group(n=8)was implanted with uncoated titanium nails in the femoral medullary canal+intra-articular injection of Staphylococcus aureus suspension;the experimental group(n=8)was implanted with composite peptide coated titanium nails in the femoral medullary canal+intra-articular injection of Staphylococcus aureus suspension.After 5 weeks of implantation,micro-CT examination,hematoxylin-eosin staining and immunohistochemical staining of femur specimens were performed.RESULTS AND CONCLUSION:(1)In vitro experiment:Compared with uncoated titanium sheet and YGF coated titanium sheet,LL-37 coated and composite peptide coated titanium sheet could significantly inhibit the growth and reproduction of Escherichia coli and Staphylococcus aureus.Compared with uncoated titanium sheets and LL-37-coated titanium sheets,YGF-coated and composite peptide-coated titanium sheets could promote calcium salt deposition in osteoblasts and increase the protein expression of RUNX2,osteocalcin,osteopontin and bone morphogenetic protein 2.(2)Animal experiment:Micro-CT test showed that the control group had less bone mass than the blank group and the experimental group.Hematoxylin-eosin staining showed that there was a large amount of fibrous tissue around the nail channel in the control group,only a small amount of tissue fibrosis around the nail channel in the blank group,and only a small amount of tissue fibrosis around the nail channel in the experimental group.Immunohistochemical staining showed that the protein expression of interleukin 1β and tumor necrosis factor α in the control group was higher than that in the blank group and the experimental group,and the expression of osteocalcin,RUNX2 and osteopontin in the experimental group was higher than that in the blank group and the control group.(3)The results show that the titanium-based material coated with YGF+LL-37 composite peptide coating has good antibacterial ability and can promote bone transfer around the implant.
8.Effects of long-term endurance exercise on kl/FGF23 axis and calcium-phosphorus metabolism in naturally aging mice
Tuanhui PENG ; Hongming SONG ; Ling YANG ; Xiaoge DING ; Pengjun MENG
Chinese Journal of Tissue Engineering Research 2026;30(5):1089-1095
BACKGROUND:Studies have shown that disorders of mineral metabolism may be responsible for premature aging and that the kl/FGF23 axis plays an important role in mineral metabolism.OBJECTIVE:To explore the effect of long-term endurance exercise on the kl/FGF23 axis in naturally aging mice,and to observe the impact of long-term endurance exercise on calcium and phosphorus metabolism,so as to provide a reference for the influence of long-term endurance exercise on natural aging.METHODS:Twenty-two 5-week-old SPF male balb/c mice were randomly divided into three groups:young and quiet control group,natural aging quiet group and natural aging exercise group.Mice in the young and quiet control group were then killed immediately.Mice in the natural aging quiet group were raised normally until 60 weeks of age.Mice in the natural aging exercise group were subjected to adaptive exercise for 1 week,followed by the maximum running speed test.The official exercise speed was set at 70%of the maximum running speed,and exercise was performed on Mondays,Wednesdays,and Fridays for 50 minutes each.Maximum running speed was retested at 8-week intervals to adjust the official exercise speed until the age of 60 weeks.(3)Enzyme-linked immunoassay was used to measure the levels of femoral fibroblast growth factor 23,renal fibroblast growth factor receptor 1,1α-hydroxylase,and serum 1,25(OH)2D3.RESULTS AND CONCLUSION:(1)Compared with the young and quiet control group,serum calcium and phosphorus levels in natural aging quiet group had no significant changes(P>0.05),but bone calcium and phosphorus levels were significantly reduced(P<0.01).Compared with the natural aging quiet group,the serum phosphorus level was significantly reduced(P<0.05),the serum calcium level did not change(P>0.05),and bone calcium and phosphorus levels were significantly increased in the natural aging exercise group(P<0.05).(2)Compared with the young and quiet control group,the level of fibroblast growth factor 23 in the femur of the natural aging quiet group was significantly increased(P<0.05).Compared with the natural aging quiet group,the level of fibroblast growth factor 23 in the femur of the natural aging exercise group was reduced,but it was not statistically significant(P>0.05).(3)Compared with the young and quiet control group,the renal Klotho protein expression,the renal fibroblast growth factor receptor 1,1α-hydroxylase,and serum 1,25(OH)2 D3 levels in the natural aging quiet group were significantly decreased(P<0.05,P<0.01).Compared with the natural aging quiet group,the levels of the above-mentioned indicators were significantly increased in the natural aging exercise group(P<0.05,P<0.01).To conclude,long-term endurance exercise can regulate Klotho protein and fibroblast growth factor 23 through the kl/FGF23 axis,thereby affecting the expression of 1α-hydroxylase and the level of 1,25(OH)2D3,and further regulating the body's calcium and phosphorus metabolism,especially phosphate metabolism.This indicates that long-term endurance exercise can delay the natural aging of the body through the kl/FGF23 axis.
9.Clinical application of an artificial intelligence system in predicting benign or malignant pulmonary nodules and pathological subtypes
Zhuowen YANG ; Zhizhong ZHENG ; Bin LI ; Yiming HUI ; Mingzhi LIN ; Jiying DANG ; Suiyang LI ; Chunjiao ZHANG ; Long YANG ; Liang SI ; Tieniu SONG ; Yuqi MENG
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2025;32(08):1086-1095
Objective To evaluate the predictive ability and clinical application value of artificial intelligence (AI) systems in the benign and malignant differentiation and pathological type of pulmonary nodules, and to summarize clinical application experience. Methods A retrospective analysis was conducted on the clinical data of patients with pulmonary nodules admitted to the Department of Thoracic Surgery, Second Hospital of Lanzhou University, from February 2016 to February 2025. Firstly, pulmonary nodules were divided into benign and non-benign groups, and the discriminative abilities of AI systems and clinicians were compared. Subsequently, lung nodules reported as precursor glandular lesions (PGL), microinvasive adenocarcinoma (MIA), and invasive adenocarcinoma (IAC) in postoperative pathological results were analyzed, comparing the efficacy of AI systems and clinicians in predicting the pathological type of pulmonary nodules. Results In the analysis of benign/non-benign pulmonary nodules, clinical data from a total of 638 patients with pulmonary nodules were included, of which there were 257 males (10 patients and 1 patient of double and triple primary lesions, respectively) and 381 females (18 patients and 1 patient of double and triple primary lesions, respectively), with a median age of 55.0 (47.0, 61.0) years. Different lesions in the same patient were analyzed as independent samples. Univariate analysis of the two groups of variables showed that, except for nodule location, the differences in the remaining variables were statistically significant (P<0.05). Multivariate logistic regression analysis showed that age, nodule type (subsolid pulmonary nodule), average density, spicule sign, and vascular convergence sign were independent influencing factors for non-benign pulmonary nodules, among which age, nodule type (subsolid pulmonary nodule), spicule sign, and vascular convergence sign were positively correlated with non-benign pulmonary nodules, while average density was negatively correlated with the occurrence of non-benign pulmonary nodules. The area under the receiver operating characteristic curve (AUC) of the malignancy risk value given by the AI system in predicting non-benign pulmonary nodules was 0.811, slightly lower than the 0.898 predicted by clinicians. In the PGL/MIA/IAC analysis, clinical data from a total of 411 patients with pulmonary nodules were included, of which there were 149 males (8 patients of double primary lesions) and 262 females (17 patients of double primary lesions), with a median age of 56.0 (50.0, 61.0) years. Different lesions in the same patient were analyzed as independent samples. Univariate analysis results showed that, except for gender, nodule location, and vascular convergence sign, the differences in the remaining variables among the three groups of PGL, MIA, and IAC patients were statistically significant (P<0.05). Multinomial multivariate logistic regression analysis showed that the differences between the parameters in the PGL group and the MIA group were not statistically significant (P>0.05), and the maximum diameter and average density of the nodules were statistically different between the PGL and IAC groups (P<0.05), and were positively correlated with the occurrence of IAC as independent risk factors. The average AUC value, accuracy, recall rate, and F1 score of the AI system in predicting lung nodule pathological type were 0.807, 74.3%, 73.2%, and 68.5%, respectively, all better than the clinical physicians’ prediction of lung nodule pathological type indicators (0.782, 70.9%, 66.2%, and 63.7% respectively). The AUC value of the AI system in predicting IAC was 0.853, and the sensitivity, specificity, and optimal cutoff value were 0.643, 0.943, and 50.0%, respectively. Conclusion This AI system has demonstrated high clinical value in predicting the benign and malignant nature and pathological type of lung nodules, especially in predicting lung nodule pathological type, its ability has surpassed that of clinical physicians. With the optimization of algorithms and the adequate integration of multimodal data, it can better assist clinical physicians in formulating individualized diagnostic and treatment plans for patients with lung nodules.
10.Association of physical activity and sedentary behavior with cardiorespiratory fitness among middle school students in Lhasa
Chinese Journal of School Health 2025;46(9):1318-1322
Objective:
To explore the relationship of physical activity (PA) and sedentary behavior (SB) with cardiorespiratory fitness (CRF) among middle schoold students in Tibet, so as to provide empirical references for improving the cardiorespiratory fitness and health levels of adolescents in Tibet.
Methods:
From August to December 2020, 1 225 junior and senior high school students were selected from 2 middle schools in Lhasa, Tibet Autonomous Region, using the stratified cluster random sampling method. Triaxial accelerometers were used to evaluate PA and SB behaviors, and the 20 meter shuttle run was employed to assess CRF among the middle school students. Isochronous substitution modeling was used to analyze the associations of SB, low intensity physical activity (LPA), and moderate vigorous physical activity (MVPA) with CRF, and the saturation threshold effect in the dose response relationship between MVPA and CRF was analyzed through restricted cubic spline and two stage linear regression.
Results:
After adjusting for covariates such as gender, body mass index and sleep quality score, isotemporal substitution analysis showed that among junior high school students aged 13-15, replacing 30 minutes of SB ( B =1.73) or LPA ( B =2.38) with MVPA were positively associated with CRF (both P <0.05). Among senior high school students aged 16-18, replacing SB ( B =0.99) or LPA ( B =1.38) with MVPA were also positively associated with CRF (both P <0.05). Restricted cubic spline and two piecewise linear regression analyses indicated that only middle school girls aged 13-18 exhibited a saturation threshold effect between MVPA and CRF (logarithmic likelihood ratio test=0.03), with the optimal CRF improvement observed at 60 minutes of MVPA per day ( B=0.13, P < 0.01).
Conclusions
Reducing SB and LPA while increasing MVPA can improve CRF in Tibetan middle school students. To maximize CRF improvement, middle school girls should engage in at least 60 minutes of MVPA daily.


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