Objective To investigate the association between cardiorespiratory fitness (CRF) and muscle strength, and the influencing factors of CRF in maintenance hemodialysis (MHD) patients. Methods It was a single-center cross-sectional study. Patients who were treated with regular MHD from September 1, 2020 to December 31, 2020 were recruited. Baseline data of MHD patients including body circumference (upper arm circumference of non-fistula, triceps skinfold thickness, and calf circumference), exercise capacity [6-min walking test (6MWT), timed up and go test (TUGT)] and upper and lower limb muscle strength (grip strength, knee extension strength) as well as clinical and biochemical data, Charlson comorbidity index were collected or measured. Cardiopulmonary exercise test (CPET) was used to test peak oxygen consumption per kg body weight (peakVO₂/kg) for reflecting CRF. Pearson correlation or Spearman correlation was used to analyze the correlation between peakVO₂/kg and clinical parameters. Multiple linear regression analysis (stepwise) was performed to analyze the influencing factors of peakVO₂/kg. Results A total of 48 patients were enrolled in the study, of whom 34 were males (70.8%). The age was (60.31±10.44) years old. The median dialysis duration was 48(15, 84) months, and the peakVO₂/kg was (12.37±2.71) ml·kg^-1·min^-1, which was well below the normal value of 30-50 ml·kg^-1·min^-1. Furthermore, peakVO₂/kg was positively correlated with lower extremity muscle strength (r=0.322, P=0.026) and 6MWT (r=0.307, P=0.034), and negatively correlated with age (r=-0.300, P=0.038). Multiple linear regression analysis demonstrated that lower extremity muscle strength (β=0.241, P=0.009) and age (β=-0.235, P=0.022) were the influencing factor of peakVO₂/kg. Conclusions CRF of MHD patients is significantly decreased. The decrease of lower extremity muscle strength is an influencing factor of CRF reduction.

Objective To evaluate the effectiveness and safety of coronavirus disease 2019 (COVID-19) vaccines for dialysis patients with chronic kidney disease. Methods PubMed, Medline, Embase databases and CNKI, VIP, Wanfang databases were searched systematically. The deadline was April 25, 2022. The search terms included haemodialysis, peritoneal dialysis, vaccine, seroresponse, COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The main outcome included the positive rate after vaccination, antibody titer, antibody changes during follow-up, infection rate of SARS-CoV-2, hospitalization rate and mortality. Results A total of 154 195 patients were analyzed in 26 studies. The results of meta-analysis showed that the positive rate of serum IgG antibody in patients with chronic kidney disease was 48% after the first dose of vaccine, 89% and 96% after the second dose and third dose, respectively. After vaccination with COVID-19 vaccines, there was no significant difference in serum antibody and titer between hemodialysis patients and peritoneal dialysis patients. However, compared with the healthy control group, the antibody positive rate and antibody titer of dialysis patients after vaccination were lower (both P<0.05). In the follow-up, the antibody positive rate at the third month decreased by 12% compared with at the first month, at the sixth month decreased by 15% compared with at the third month, and at the sixth month decreased by 20% compared with at the first month. The serum antibody positive rate after the third dose of vaccine increased by 38% (RR=1.38, 95%CI 1.12-1.70, P<0.001), and the antibody titer increased significantly (SMD=1.46, 95%CI 0.31-2.61, P<0.001). Although the vaccines could not reduce the infection rate of SARS-CoV-2 in dialysis patients, it could significantly reduce the hospitalization rate and mortality after infection. Conclusions After vaccination with COVID-19 vaccines, dialysis patients can produce strong serum antibodies, which can reduce the hospitalization rate and mortality after SARS-CoV-2 infection. However, the duration of antibody is short and the titer level is low, so it is necessary to timely vaccinate booster vaccine dose to obtain stronger immunogenicity.

Objective To investigate the patency rates and risk factors of arteriovenous graft (AVG), and provide a clinical guidance for further optimization of vascular access selection and improvement of dialysis quality. Methods This was a retrospective study. The clinical and follow-up data of patients who received AVG in the Blood Purification Center, First Affiliated Hospital of Zhengzhou University from January 1, 2017 to December 31, 2021 were selected. Kaplan-Meier curve and Cox regression model were used to analyze the patency rates and risk factors of AVG. Results A total of 381 cases with AVG were included, with 154 cases (40.4%) of males, age of (55.5±11.8) years old, and 140 cases (36.7%) of diabetes. The median time of primary patency was 377.00(95%CI 314.26-439.74) days, and the primary patency rates at 1, 2, and 3 years were 51.0%, 30.7%, and 15.4%, respectively. The median time of primary assisted patency was 839.00(95%CI 668.89-1 009.11) days, and the primary assisted patency rates at 1, 2, and 3 years were 78.3%, 56.4%, and 39.1%, respectively. The secondary patency rates at 1, 2, and 3 years were 96.7%, 90.1%, and 78.5%, respectively. Multivariate Cox regression analysis results showed that anastomotic vein types of basilic vein and cephalic vein (median cubital vein as a reference, HR=1.869, 95%CI 1.124-3.107, P=0.016; HR=2.110, 95%CI 1.176-3.786, P=0.012) and the diameter of anastomotic vein<3.5 mm (HR=1.411, 95%CI 1.020-1.952, P=0.037) were the independent influencing factors for abnormal primary patency of AVG. Males (HR=1.680, 95%CI 1.127-2.503, P=0.011), mean arterial pressure<70 mmHg (HR=3.228, 95%CI 1.109-9.394, P=0.032), Acuseal graft type (Intering as a reference, HR=1.884, 95%CI 1.185-2.994, P=0.007), anastomotic vein type of cephalic vein (median cubital vein as a reference, HR=2.817, 95%CI 1.328-5.977, P=0.007), the diameter of anastomotic vein<3.5 mm (HR=1.555, 95%CI 1.048-2.306, P=0.028), serum phosphorus ≤1.78 mmol/L (1.13-1.78 mmol/L />1.78 mmol/L, HR=1.737, 95%CI 1.111-2.716, P=0.015;<1.13 mmol/L />1.78 mmol/L, HR=2.162, 95%CI 1.072- 4.362, P=0.031), and ferritin<200 μg/L (HR=1.850, 95%CI 1.231-2.780, P=0.003) were the independent influencing factors for abnormal primary assisted patency of AVG. Serum albumin<40 g/L (HR=2.165, 95%CI 1.096-4.275, P=0.026) was an independent influencing factor for abnormal secondary patency of AVG. Conclusions The primary patency rates of AVG at 1, 2, and 3 years were 51.0%, 30.7%, and 15.4%, respectively. The secondary patency rates of AVG at 1, 2, and 3 years were 96.7%, 90.1%, and 78.5%, respectively. Anastomotic vein types of cephalic vein and basilic vein, and internal diameter<3.5 mm are the independent risk factors for abnormal primary patency of AVG. Anastomotic vein type of cephalic vein and internal diameter<3.5 mm are the independent risk factors for abnormal assisted primary patency of AVG. Serum albumin<40 g/L is an independent risk factor for abnormal secondary patency of AVG. It is suggested that systematic preoperative evaluation and good nutritional status of patients are important to maintain long-term patency of the AVG.

Objective To investigate the prevalence of chronic constipation in maintenance hemodialysis (MHD) patients and analyze the risk factors of chronic constipation. Methods Using the cross-sectional survey method, patients who received MHD in Huadu District People′s Hospital of Guangzhou from September 1, 2021 to September 30, 2021 were enrolled as the research objects. The patient′s demographic, general data and laboratory results were collected. The anxiety level and quality of life were assessed by questionnaires. The patients were divided into constipation group and non-constipation group according to whether they had chronic constipation. The Rome Ⅳ criteria was used to diagnose chronic constipation, and the differences of clinical data between the constipation group and the non-constipation group were compared. The risk factors of chronic constipation in MHD patients were analyzed by logistic regression analysis method. Results A total of 321 MHD patients were enrolled in this study, with 168 males, 153 females and age of (59.5±13.4) years old (ranged from 29 to 87 years old). There were 160 patients (49.8%) with chronic constipation. The proportions of males, long dialysis age, taking sevelamer and lanthanum carbonate, diabetic nephropathy, and diabetes in the constipation group were higher than those in the non-constipation group, and the differences between the two groups were statistically significant (all P<0.05). The serum calcium, serum phosphorus, calcium-phosphorus product, anxiety scores, average weekly ultrafiltration volume/dry weight in the constipation group were significantly higher than those in the non-constipation group (all P<0.05), and the serum albumin, serum magnesium, urea clearance index (Kt/V) and geriatric nutritional risk index were significantly lower than those in the non-constipation group (all P<0.05). The results of logistic regression analysis showed that moderate to severe anxiety (moderate, OR=3.233, 95%CI 1.339-7.805, P=0.009; severe, OR=5.103, 95%CI 1.906-13.663, P=0.001), existed risk of nutrition (low risk, OR=3.705, 95%CI 1.440-9.533, P=0.007; moderate risk, OR=5.638, 95%CI 2.557-12.430, P<0.001; severe risk, OR=15.097, 95%CI 4.112-55.436, P<0.001), >60 years old (≤40 years old as a reference, OR=4.050, 95%CI 1.366-12.006, P=0.012), diabetes history (OR=2.224, 95%CI 1.253-3.946, P=0.006), taking sevelamer (OR=2.290, 95%CI 1.207-4.346, P=0.011), and calcium-phosphorus product (OR=1.704, 95%CI 1.329-2.186, P<0.001), intact parathyroid hormone (OR=1.013, 95%CI 1.003-1.022, P=0.007), blood urea nitrogen (OR=1.092, 95%CI 1.002-1.189, P=0.045) and serum magnesium (OR=0.042, 95%CI 0.006-0.294, P=0.001) were the independent influencing factors for chronic constipation in MHD patients. Conclusions The prevalence of chronic constipation in MHD patients is 49.8%. Adequate dialysis, improving calcium and phosphorus metabolism, improving nutritional status, relieving anxiety, and increasing serum magnesium level may help to reduce the risk of chronic constipation in MHD patients.

Objective To explore the role of prostacyclin (PGI₂) in the development of kidney and vascular system in mice. Methods The prostacyclin synthase (PGIS) knockout model was established in C57BL/6J mice. The effects of PGIS knockout on the survival rate of mice were observed by genotyping analysis. The effects of PGIS knockout on the development of kidney and vascular system in mice were observed by hematoxylin and eosin staining and periodic acid-Schiff staining. The morphological changes of kidneys in PGIS knockout mice were observed. Blood urea nitrogen was tested to evaluate the function of kidney in mice. Real-time quantitative PCR was used to analyze the effect of PGIS knockout on the mRNA expression of prostaglandin synthetase PGES and TXAS. The expression of PGIS in vascular system was observed by immunofluorescence staining. The blood pressure and heart rate of mice were measured by the tail-cuff method. Results Most of the systemic complete PGIS knockout (PGIS^-/-) fetal mice sacrificed. The kidneys of PGIS^-/- fetal mice developed abnormally, which showed sparse interstitial, abnormal tissue differentiation, lengthened renal vesicle, and significant decrease in the number of “S”-shape bodies (P<0.01). The kidneys of PGIS^-/- mice showed tissue atrophy, surface irregularities and cyst formation. Blood urea nitrogen level in the PGIS^-/- mice was significantly higher than that in the wild type (PGIS^+/+) mice [(36.89±5.39) mmol/L vs (5.07±0.69) mmol/L, n=3, P<0.01]. There was no significant difference in the mRNA expression of PGES and TXAS between PGIS^+/+ mice and PGIS^-/-mice. PGIS was widely expressed in renal vascular endothelial cells and smooth muscle cells of PGIS^+/+ mice. Vascular system developed abnormally, which showed loss of smooth muscle layer, width of subendothelial loose layer, thinning of the pipe wall, and discontinuity of the inner elastic plate in PGIS^+/- mice. There was no significant difference in the blood pressure and heart rate between PGIS systemic half-knockout (PGIS^+/-) mice and PGIS^-/- mice. Conclusion PGIS plays an important role in the development of kidney and vascular system in mice.

Objective To investigate whether hepatitis B virus X protein (HBx) mediates the podocyte injury through reactive oxygen species (ROS) /nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) signaling pathway. Methods HBx-overexpressing lentivirus was transfected into renal podocytes of mouse to mimic the pathogenesis of hepatitis B virus-associated glomerulonephritis. Podocytes were divided into the following five groups: blank control group (no special treatment), negative control group (transfected with control lentivirus), HBx overexpression group (transfected with HBx overexpression lentivirus), HBx overexpression+NLRP3 siRNA group (transfected with HBx overexpression lentivirus and NLRP3 siRNA), and HBx overexpression+ROS inhibitor group (transfected with HBx overexpression lentivirus and adding ROS inhibitor). The morphological changes of podocytes were observed with electron microscope. The generation of ROS was detected by dichlorodihydrofluorescein diacetate assay (DCFH-DA). Hoechst 33342 staining was used to observe the morphological and quantitative changes of podocyte nuclei. Enzyme-linked immunosorbent assay was used to detect caspase-1 activity, and the levels of lactate dehydrogenase, interleukin (IL)-1β and IL-18. Quantitative real-time polymerase chain reaction and Western blotting were used to detect the expression levels of mRNA and protein of pyroptosis-related protein, such as NLRP3, apoptosis-associated speck-like protein containing card (ASC), caspase-1, IL-1β and IL-18. TUNEL staining and flow cytometer were used to detect the number of pyroptosis cells. Immunofluorescence staining was used to detect the expression levels of desmin and nephrin. Results After successful infection of podocytes with HBx-overexpressing lentivirus, pyroptosis-related morphological changes in the cells were observed under electron microscope. The level of ROS in the HBx overexpression group was significantly higher compared to the negative control group (P<0.05). Hoechst 33342 staining revealed condensed nuclei in the HBx overexpression group. TUNEL staining and flow cytometer demonstrated that podocytes underwent increased pyroptosis in the HBx overexpression group. The mRNA and protein expression levels of pyroptosis-related proteins such as NLRP3, ASC, caspase-1, IL-1β and IL-18 were up-regulated upon HBx overexpression (all P<0.05). Caspase-1 enzyme activity, lactate dehydrogenase and desmin expression levels were enhanced after HBx overexpression (all P<0.05). However, NLRP3 knockdown or addition of ROS inhibitors attenuated the pyroptosis and increased expression levels of pyroptosis-related proteins caused by HBx overexpression (all P<0.05). Conclusion ROS/NLRP3 pathway plays an important role in HBx-induced podocyte pyroptosis.