1.Time series study on influence of sulfur dioxide exposure on hospitalization of chronic obstructive pulmonary disease in Lanzhou from 2016 to 2020
Sheng LIN ; Boxi FENG ; Yongyue LI ; Yiwei HUANG ; Kai ZHENG ; Mingxuan LIU ; Yingying YANG ; Xingmin WEI ; Jianjun WU
Journal of Environmental and Occupational Medicine 2026;43(4):451-457
Background In 2021, chronic obstructive pulmonary disease (COPD) emerged as the forth leading cause of death in the world. However, the impact of air pollutants on COPD is still inconsistent across current studies. Objective To analyze the relationship between ambient sulfur dioxide (SO2) exposure and hospital admissions for COPD in Lanzhou, and to examine the modified effects of SO2 across different genders, age groups, and seasons. Methods A total of
2.Discussion on Theory of "Gaozhuo" and Syndrome Differentiation and Treatment for Microcirculatory Disorders in Diabetic Retinopathy
Kai WU ; Yunfeng YU ; Xiangning HUANG ; Qianhong LIU ; Fangfang LI ; Rong YU ; Xiaolei YAO
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(2):245-252
Retinal microcirculatory disorder is a key factor in the occurrence and development of diabetic retinopathy (DR), and also an important link in the prevention and treatment of DR. The theory of "Gaozhuo" holds that the microcirculatory disorder in DR is based on the deficiency of spleen Qi and is characterized by the obstruction caused by "Gaozhuo" and blood stasis. The deficiency of spleen Qi is an essential precondition for the endogenous formation and accumulation of Gaozhuo, while Gaozhuo invasion is the direct cause of microcirculatory disorders in DR. The deficiency of spleen Qi and the endogenous formation of Gaozhuo mean the process in which glucose metabolism dysfunction induces an excessive production of inflammatory factors and lipid metabolites. The obstruction caused by "Gaozhuo" and blood stasis is the direct pathogenesis of microcirculatory disorders in DR, encompassing two stages: Gaozhuo obstruction and turbidity and stasis stagnation. Gaozhuo obstruction and turbidity and stasis stagnation represent the process in which inflammatory factors and lipid metabolites damage the retinal microcirculation and induce thrombosis, thus mediating microcirculatory disorders. Turbidity and stasis stagnation and blood extravasation outside the vessels reveal the progression to microvascular rupture and hemorrhage resulting from the microcirculatory disorders. According to the pathogenesis evolution of the theory of "Gaozhuo", microcirculatory disorders in DR can be divided into deficiency of spleen Qi with Gaozhuo obstruction, deficiency of spleen Qi with turbidity and stasis stagnation, and turbidity and stasis stagnation with blood extravasation outside the vessels. Clinically, treatment principles should focus on strengthening the spleen and benefiting Qi, resolving turbidity, and dispersing stasis. Different syndrome patterns should be addressed with tailored therapies, such as enhancing the spleen and benefiting Qi while regulating Qi and reducing turbidity, strengthening the spleen and benefiting Qi while resolving turbidity and dispelling stasis, and strengthening the spleen and resolving turbidity while removing stasis and stopping bleeding. Representative prescriptions include modified Wendantang, modified Buyang Huanwutang, modified Danggui Buxuetang, Zhuixue Mingmu decoction, Tangmuqing, Shengqing Jiangzhuo Tongluo Mingmu prescription, Danhong Huayu decoction, and Yiqi Yangyin Huoxue Lishui formula.
3.A VBM study on gray matter structure alterations in patients with Alzheimer’s disease comorbid with apathy
Yi JI ; Xuerui PANG ; Chaoyi YANG ; Yulong DAI ; Shanshan ZHOU ; Xingqi WU ; Kai WANG
Acta Universitatis Medicinalis Anhui 2026;61(1):156-162
ObjectiveTo investigate the characteristics of gray matter structure and clinical symptoms in patients with Alzheimer's disease (AD) comorbid with apathy (AD-A). MethodsThe study included 30 patients with AD-A, 30 AD disease patients without apathy (AD without apathy, AD-NA), and 30 healthy controls (HCs) matched in gender, age, and years of education. All participants underwent a comprehensive neuropsychological assessment and magnetic resonance imaging (MRI) scans. Voxel-based morphometry (VBM) was used to analyze changes in gray matter volume among the three groups. Additionally, the correlation between the identified abnormal brain regions and apathy scale scores was analyzed. ResultsThere were no statistically significant differences among the three groups in terms of age, gender, years of education, or total intracranial volume. Compared with the HCs group, both the AD-A and AD-NA groups showed significantly lower scores in cognitive function (P<0.001). The AD-A group exhibited significantly higher apathy scale scores compared with the AD-NA group (P<0.001). Compared with the AD-NA group, the AD-A group showed reduced gray matter volume in the bilateral caudate nucleus, left orbitofrontal cortex, lingual gyrus, inferior frontal gyrus, superior frontal gyrus, entorhinal cortex, right middle frontal gyrus and posterior cingulate cortex (FWE-corrected, P<0.05 for all). Compared with the HCs group, the AD-A group exhibited reduced gray matter volume in the bilateral middle temporal gyrus, left fusiform gyrus, calcarine sulcus, postcentral gyrus, right inferior frontal gyrus and supramarginal gyrus (FWE-corrected, P<0.05 for all). Compared with the HCs group, the AD-NA group showed reduced gray matter volume in the left precuneus, inferior temporal gyrus, and right inferior temporal gyrus (FWE-corrected, P<0.05 for all). In the AD-A group, changes in the gray matter volume of the left caudate nucleus (r= -0.557, P=0.002) and right middle frontal gyrus (r=-0.620, P=0.001) were negatively correlated with the apathy evaluation scale (AES) scores. ConclusionPatients in the AD-A group exhibited significant atrophy in the frontal-temporal-basal ganglia circuit, and the degree of gray matter atrophy was correlated with the severity of apathy.
4.Dosimetric comparison and analysis of AXB and AAA algorithms in postoperative radiotherapy planning for left-sided breast cancer after breast-conserving surgery
Jianhui WU ; Yufeng GAO ; Kai GAO ; Chengqiong TANG ; Jiao LIU
Chinese Journal of Radiological Health 2026;35(1):120-127
Objective To investigate the impact of two different algorithms, AAA and AXB, on the dose distribution of postoperative radiotherapy for left-sided breast cancer after breast-conserving surgery. Methods A total of 96 target volumes from patients who underwent breast-conserving surgery for left-sided breast cancer were selected for dose verification using a two-dimensional matrix system. The planned dose distributions were simulated using both AAA and AXB algorithms. Dosimetric differences in organs at risk and the target volumes were then compared to identify the algorithm that could reduce the radiation dose to organs at risk without compromising the dose distribution to the target volume. Dose verification was performed on the plans generated by both algorithms, and the pass rates of plans for each target volume using both algorithms were compared to provide a quantitative basis for the precise selection of subsequent radiotherapy plans. Results Both AAA and AXB plans met the radiotherapy requirements. The AXB algorithm demonstrated significant advantages in the D98, D2, homogeneity index, and conformity index for the planning target volume, as well as in the V5 and V20 for the left lung. The AXB algorithm showed advantages in the V30 for the heart and the maximum and mean doses for the skin. With the 2 mm/2% criterion in dose verification, the gamma pass rate was higher for the AXB algorithm. Conclusion Through a comparative analysis of the two algorithms, this study revealed that the AXB algorithm offers certain advantages in the dose distribution of radiotherapy after breast-conserving surgery for left-sided breast cancer. These findings provide an important reference for the rational selection of algorithms in clinical practice and are expected to improve radiotherapy efficacy and patient prognosis.
5.Mechanisms of Anemarrhenae Rhizoma Water Extract in Ameliorating Neuroinflammation in Alzheimer's Disease Model Rats via SIRT1/HMGB1/NF-κB Signaling Pathway
Fei WU ; Yuexia LI ; Qi HUANG ; Tianshi LI ; Chuanshan JIN ; Kai MA
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(7):230-240
ObjectiveTo investigate the therapeutic effects of the Anemarrhenae Rhizoma water extract (AR) on Alzheimer's disease (AD) model rats and to explore its potential underlying mechanisms. MethodsMale rats were intraperitoneally injected with D-galactose (100 mg·kg-1) for 42 days, and on day 14, 1 μL of β-amyloid (Aβ25-35, 2 g·L-1) solution was injected into the hippocampus. Rats were randomly divided into a model group, low-dose AR (0.6 g·kg-1), medium-dose AR (1.2 g·kg-1), high-dose AR (2.4 g·kg-1), and a positive control group (donepezil, 5 mg·kg-1). Healthy rats receiving only a hippocampal injection of 1 μL of sterile saline served as the sham-operated group. From day 21, rats in the treatment groups were administered the corresponding drugs by gavage once daily for 21 consecutive days, while the blank control and model groups received an equal volume of saline. Learning and memory abilities were assessed using the Morris water maze. Brain tissue damage was observed by hematoxylin and eosin (HE) staining, and neuronal apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. Levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) in brain tissues were measured by enzyme-linked immunosorbent assay (ELISA). BV2 microglial cells were co-cultured with Aβ25-35 (40 μmol·L-1) for 2 h, and cell viability was determined by the CCK-8 assay to screen the optimal concentration of AR-containing serum (S-AR). Cells were divided into blank control, Aβ25-35, S-AR, EX527 [silent information regulator 1 (SIRT1) inhibitor], and S-AR+EX527 groups. Immunofluorescence staining was used to detect the expression of CD16, CD206, and high-mobility group box 1 (HMGB1). Western blot analysis was performed to measure the protein expression of CD16, inducible nitric oxide synthase (iNOS), CD206, arginase (Arg), and proteins related to the SIRT1/HMGB1/nuclear factor-κB (NF-κB) signaling pathway. ResultsIn vivo experiments showed that, compared with the sham-operated group, the model group exhibited reduced platform crossings and time spent in the target quadrant (P<0.01), prolonged escape latency, increased hippocampal neuronal apoptosis (P<0.01), and obvious hippocampal damage. The expression levels of IL-6, TNF-α, IL-10, CD16, and iNOS in brain tissues were significantly elevated (P<0.01), while CD206 and Arg protein expression showed an increasing trend without statistical significance. Compared with the model group, all AR-treated groups significantly increased platform crossings and target quadrant time (P<0.05, P<0.01), alleviated hippocampal damage, reduced escape latency and neuronal apoptosis, downregulated the expression of TNF-α, IL-6, CD16, and iNOS (P<0.05, P<0.01), and upregulated the expression of IL-10, CD206 and Arg (P<0.05, P<0.01). In vitro experiments demonstrated that, compared with the blank control group, the Aβ25-35 group showed increased fluorescence intensity of CD206, CD16, and HMGB1, as well as elevated protein expression of iNOS and CD16 (P<0.01), while CD206 and Arg protein expression exhibited an increasing trend without statistical significance. After S-AR intervention, CD206 fluorescence intensity and the protein expression of Arg and CD206 were significantly increased (P<0.01), whereas the fluorescence intensity of CD16 and HMGB1 and the protein expression of iNOS and CD16 were significantly decreased (P<0.01). These effects were reversed by EX527 (P<0.05, P<0.01). Furthermore, compared with the blank control group, the Aβ25-35 group showed significantly increased cytoplasmic HMGB1 expression and p-p65/p65 ratio (P<0.01), along with significantly decreased SIRT1 and nuclear HMGB1 expression (P<0.01). In contrast, the S-AR group exhibited opposite trends compared with the Aβ25-35 group, and the regulatory effects of S-AR on these proteins were reversed by EX527 (P<0.01). ConclusionAR exerts neuroprotective effects in AD model rats by regulating microglial polarization and alleviating neuroinflammation, potentially through modulation of the SIRT1/HMGB1/NF-κB signaling pathway.
6.Phenotypic heterogeneity and management strategies for two brothers with XIAP deficiency syndrome.
Hui HU ; Shengnan WU ; Kai CHEN ; Jingbo SHAO ; Ting ZHANG ; Yongmei XIAO
Chinese Journal of Medical Genetics 2026;43(2):123-128
OBJECTIVE:
To summarize the clinical features and management of two brothers affected with X-linked inhibitor of apoptosis protein (XIAP) deficiency.
METHODS:
This study retrospectively analyzed the clinical presentations, treatment, and follow-up of two brothers with XIAP deficiency diagnosed at Shanghai Children's Hospital in 2020, and summarized similar cases recorded in databases such as PubMed, Wanfang, Chinese Medical Association Journals, and WIP from January 2006 to November 2024. This study was approved by the Medical Ethics Committee of our hospital (Ethics No.: 2025R128-E01).
RESULTS:
Patient 1 was the younger brother, who presented at 8 years of age with growth retardation, folliculitis, erythema nodosum, and perineal abscess. Sequencing revealed that he has carried a hemizygous c.566T>C (p.Leu189Pro) variant of the XIAP gene, which was inherited from his mother. He was allergic to infliximab treatment and underwent allogeneic stem cell transplantation (HSCT) in January 2021. During a follow-up of 3 years and 10 months post-transplantation, he showed no gastrointestinal symptoms and had a good outcome. Patient 2 was the elder brother, who presented at 10 years and 6 months of age with growth retardation, rash, and anal fistula. Genetic testing revealed the same variant. He was treated with oral azathioprine but did not have regular follow-ups. At 14-years-and-6-months of age, he had developed severe gastrointestinal infection and hemophagocytic lymphohistiocytosis, which was alleviated after treatment with antibiotics, glucocorticoids, immunoglobulin, and rituximab. He is currently being prepared for HSCT. A total of 13 publications were retrieved, which involved 64 patients from 23 families, with 23 different variants identified. The main clinical manifestations included splenomegaly (34 cases, 53.1%), hemophagocytic lymphohistiocytosis (27 cases, 42.2%), and inflammatory bowel disease or colitis (20 cases, 31.8%). There were significant phenotypic differences among patients from the same family. Thirteen patients (20.3%) underwent HSCT, with a survival rate of 61.5%.
CONCLUSION
For male children with early onset, poor treatment response, especially those with unexplained splenomegaly and IBD-like symptoms, early genetic testing is recommended. HSCT is a safe and effective treatment for XIAP deficiency. For patients with developmental delay, early onset, and severe IBD phenotype, early transplantation is recommended.
Humans
;
Male
;
X-Linked Inhibitor of Apoptosis Protein/deficiency*
;
Child
;
Genetic Diseases, X-Linked/therapy*
;
Phenotype
;
Siblings
;
Retrospective Studies
;
Hematopoietic Stem Cell Transplantation
7.Long-term survival outcomes and prognostic factors following radical resection of pancreatic body and tail cancer:a retrospective analysis of 992 patients
Dong XU ; Yang WU ; Kai ZHANG ; Nan LYU ; Qianqian WANG ; Pengfei WU ; Jie YIN ; Baobao CAI ; Guodong SHI ; Jianzhen LIN ; Yazhou WANG ; Lingdi YIN ; Zipeng LU ; Min TU ; Jianmin CHEN ; Feng GUO ; Jishu WEI ; Junli WU ; Wentao GAO ; Cuncai DAI ; Yi MIAO ; Kuirong JIANG
Chinese Journal of Surgery 2026;64(1):46-54
Objective:To investigate the survival outcomes and prognostic factors in patients undergoing radical resection for pancreatic body and tail cancer.Methods:A retrospective case series study was conducted on 992 patients who underwent radical resection for pancreatic body and tail cancer at the Pancreatic Center of the First Affiliated Hospital of Nanjing Medical University from January 2016 to June 2024. In this study, 577 (58.2%) were male and 415 (41.8%) were female,with an age of (65±9) years (range: 26 to 86 years). Follow-up continued until June 2024. Survival rates were estimated using the Kaplan-Meier method,and prognostic factors were identified using univariate and multivariate Cox proportional hazards models.Results:Among 992 patients,open surgery was the predominant approach (89.1%, 884/992), and radical antegrade modular pancreatosplenectomy (RAMPS) was performed in 317 patients (32.0%). Combined organ resection,venous resection,and arterial resection were performed in 23.5%, 9.3%,and 11.2% of patients,respectively. The rates of R0, R1-1 mm, and R1-direct resections were 49.8% (494/992),41.5% (412/992), and 8.7% (86/992),respectively. Stage ⅡB was the most common TNM stage (32.2%,319/992). A total of 801 patients (80.8%) received adjuvant chemotherapy. The median follow-up period was 32.0(8.8) months(range:3.2 to 105.3 months),during which 508 patients (51.2%) died. The overall median survival (OS) was 26.4 months,with 1-,3-, and 5-year survival rates of 79.0%,40.0%, and 29.0%, respectively. In the recent five years (from 2020 to 2024), the median OS improved significantly to 34.1 months compared to 20.0 months from 2016 to 2019 ( P<0.01). Histological subtype analysis showed that the median OS time was 26.7 months for pancreatic ductal adenocarcinoma (PDAC, n=855),58.9 months for invasive intraductal papillary mucinous carcinoma (IPMC, n=32),and 15.7 months for adenosquamous carcinoma of pancreas (ASCP, n=73) ( P=0.001). Among PDAC patients, adjuvant chemotherapy significantly improved survival (29.1 months vs. 14.4 months, P<0.01);in IPMC patients, adjuvant chemotherapy also extended survival (65.7 months vs. 58.9 months, P=0.047). Although ASCP patients receiving chemotherapy had a longer median OS time than those without (18.8 months vs. 8.9 months),the difference was not statistically significant ( P=0.151). Multivariate Cox regression analysis in PDAC patients indicated that adjuvant chemotherapy, R0 resection, T stage,N stage,and tumor differentiation were independent prognostic factors ( P<0.01). The median OS time by TNM stage was:not reached for stage ⅠA, 51.6 months for ⅠB, 25.5 months for ⅡA, 23.7 months for ⅡB, 23.0 months for Ⅲ, and 14.4 months for Ⅳ. The median OS time for R0,R1-1 mm,and R1-direct resections was 34.1,24.7,and 15.7 months,respectively ( P<0.01). Conclusion:Adjuvant chemotherapy,R0 resection,tumor stage,and differentiation are independent prognostic factors for pancreatic body and tail cancer.
8.Long-term survival outcomes and prognostic factors following radical resection of pancreatic body and tail cancer:a retrospective analysis of 992 patients
Dong XU ; Yang WU ; Kai ZHANG ; Nan LYU ; Qianqian WANG ; Pengfei WU ; Jie YIN ; Baobao CAI ; Guodong SHI ; Jianzhen LIN ; Yazhou WANG ; Lingdi YIN ; Zipeng LU ; Min TU ; Jianmin CHEN ; Feng GUO ; Jishu WEI ; Junli WU ; Wentao GAO ; Cuncai DAI ; Yi MIAO ; Kuirong JIANG
Chinese Journal of Surgery 2026;64(1):46-54
Objective:To investigate the survival outcomes and prognostic factors in patients undergoing radical resection for pancreatic body and tail cancer.Methods:A retrospective case series study was conducted on 992 patients who underwent radical resection for pancreatic body and tail cancer at the Pancreatic Center of the First Affiliated Hospital of Nanjing Medical University from January 2016 to June 2024. In this study, 577 (58.2%) were male and 415 (41.8%) were female,with an age of (65±9) years (range: 26 to 86 years). Follow-up continued until June 2024. Survival rates were estimated using the Kaplan-Meier method,and prognostic factors were identified using univariate and multivariate Cox proportional hazards models.Results:Among 992 patients,open surgery was the predominant approach (89.1%, 884/992), and radical antegrade modular pancreatosplenectomy (RAMPS) was performed in 317 patients (32.0%). Combined organ resection,venous resection,and arterial resection were performed in 23.5%, 9.3%,and 11.2% of patients,respectively. The rates of R0, R1-1 mm, and R1-direct resections were 49.8% (494/992),41.5% (412/992), and 8.7% (86/992),respectively. Stage ⅡB was the most common TNM stage (32.2%,319/992). A total of 801 patients (80.8%) received adjuvant chemotherapy. The median follow-up period was 32.0(8.8) months(range:3.2 to 105.3 months),during which 508 patients (51.2%) died. The overall median survival (OS) was 26.4 months,with 1-,3-, and 5-year survival rates of 79.0%,40.0%, and 29.0%, respectively. In the recent five years (from 2020 to 2024), the median OS improved significantly to 34.1 months compared to 20.0 months from 2016 to 2019 ( P<0.01). Histological subtype analysis showed that the median OS time was 26.7 months for pancreatic ductal adenocarcinoma (PDAC, n=855),58.9 months for invasive intraductal papillary mucinous carcinoma (IPMC, n=32),and 15.7 months for adenosquamous carcinoma of pancreas (ASCP, n=73) ( P=0.001). Among PDAC patients, adjuvant chemotherapy significantly improved survival (29.1 months vs. 14.4 months, P<0.01);in IPMC patients, adjuvant chemotherapy also extended survival (65.7 months vs. 58.9 months, P=0.047). Although ASCP patients receiving chemotherapy had a longer median OS time than those without (18.8 months vs. 8.9 months),the difference was not statistically significant ( P=0.151). Multivariate Cox regression analysis in PDAC patients indicated that adjuvant chemotherapy, R0 resection, T stage,N stage,and tumor differentiation were independent prognostic factors ( P<0.01). The median OS time by TNM stage was:not reached for stage ⅠA, 51.6 months for ⅠB, 25.5 months for ⅡA, 23.7 months for ⅡB, 23.0 months for Ⅲ, and 14.4 months for Ⅳ. The median OS time for R0,R1-1 mm,and R1-direct resections was 34.1,24.7,and 15.7 months,respectively ( P<0.01). Conclusion:Adjuvant chemotherapy,R0 resection,tumor stage,and differentiation are independent prognostic factors for pancreatic body and tail cancer.
9.Research on a COPD Diagnosis Method Based on Electrical Impedance Tomography Imaging
Fang LI ; Bai CHEN ; Yang WU ; Kai LIU ; Tong ZHOU ; Jia-Feng YAO
Progress in Biochemistry and Biophysics 2025;52(7):1866-1877
ObjectiveThis paper proposes a novel real-time bedside pulmonary ventilation monitoring method for the diagnosis of chronic obstructive pulmonary disease (COPD), based on electrical impedance tomography (EIT). Four indicators—center of ventilation (CoV), global inhomogeneity index (GI), regional ventilation delay inhomogeneity (RVDI), and the ratio of forced expiratory volume in one second to forced vital capacity (FEV1/FVC)—are calculated to enable the spatiotemporal assessment of COPD. MethodsA simulation of the respiratory cycles of COPD patients was first conducted, revealing significant differences in certain indicators compared to healthy individuals. The effectiveness of these indicators was then validated through experiments. A total of 93 subjects underwent multiple pulmonary function tests (PFTs) alongside simultaneous EIT measurements. Ventilation heterogeneity under different breathing patterns—including forced exhalation, forced inhalation, and quiet tidal breathing—was compared. EIT images and related indicators were analyzed to distinguish healthy individuals across different age groups from COPD patients. ResultsSimulation results demonstrated significant differences in CoV, GI, FEV1/FVC, and RVDI between COPD patients and healthy individuals. Experimental findings indicated that, in terms of spatial heterogeneity, the GI values of COPD patients were significantly higher than those of the other two groups, while no significant differences were observed among healthy individuals. Regarding temporal heterogeneity, COPD patients exhibited significantly higher RVDI values than the other groups during both quiet breathing and forced inhalation. Moreover, during forced exhalation, the distribution of FEV1/FVC values further highlighted the temporal delay heterogeneity of regional lung function in COPD patients, distinguishing them from healthy individuals of various ages. ConclusionEIT technology effectively reveals the spatiotemporal heterogeneity of regional lung function, which holds great promise for the diagnosis and management of COPD.
10.Dynamic Monitoring and Analysis of Ammonia Concentration in Laboratory Animal Facilities Under Suspension of Heating Ventilation and Air Conditioning System
Qingzhen JIAO ; Guihua WU ; Wen TANG ; Fan FAN ; Kai FENG ; Chunxiang YANG ; Jian QIAO ; Sufang DENG
Laboratory Animal and Comparative Medicine 2025;45(4):490-495
ObjectiveTo monitor the real-time changes in ammonia concentration in the laboratory animal facility environment before, during, and after the air conditioning system stops supplying air, so as to provide a basis and reference for developing emergency plans for the shutdown of the air conditioning system. MethodsThe laboratory animal facilities of the Wuhan Institute of Biological Products were used as the research object. Ammonia concentration detectors were used to monitor ammonia concentration continuously in the environment of conventional rabbit production facility, SPF hamster production facility, and SPF guinea pig experimental facility before and after the passive shutdown due to repairs and active maintenance shutdown of the air conditioning system, as well as the time for the ammonia concentration to return to daily levels after resuming air supply. ResultsUnder both shutdown modes of the air conditioning system, the trend of ammonia concentration changes in different laboratory animal facilities was consistent, showing a rapid increase after shutdown and a rapid decrease after resuming air supply. Under active maintenance shutdown, the maximum ammonia concentrations in the conventional rabbit production facilities, SPF hamster production facilities, and SPF guinea pig experimental facilities were 9.81 mg/m³, 14.27 mg/m³, and 6.98 mg/m³, respectively. Within 12 minutes after resuming air supply, ammonia concentration could return to normal daily levels. Under passive long-term shutdown, ammonia concentration value was positively correlated with the duration of air supply suspension. As the shutdown duration increased, ammonia concentration continued to increase. The maximum ammonia concentration values in the three facilities occurred at 88 minutes (38.06 mg/m³), 40 minutes (18.43 mg/m³), and 34 minutes (15.61 mg/m³) after air supply suspension, respectively.Within 11 minutes after resuming air supply, ammonia concentration could return to normal daily levels. ConclusionShutdown of the air conditioning system causes a rapid increase in ammonia concentration in laboratory animal facilities, and the rise in ammonia concentration is positively correlated with the duration of air supply suspension. Therefore, when an emergency shutdown of the air-conditioning system is required due to maintenance or other reasons, backup fans should be provided in accordance with the requirements of GB 50447-2008 "Architectural and Technical Code for Laboratory Animal Facilities". Older facilities should make adequate preparations and develop a scientifically sound emergency plan.

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