Objective To study the effect of storage duration on compressive mechanical properties of rabbit patellar, so as to provide references for in vitro ligament storage.Methods The compressive mechanical properties of rabbit patellar ligament storaged at -20 ℃ at different storage durations (in 36 d) were tested with the universal tensile test machine. The microscopic morphology of collagen fibers was observed under the scanning electron microscopy (SEM). The enthalpy and denaturation temperature of collagen fibers were measured with differential scanning calorimetry (DSC).Results With the increase of storage duration, the compressive stress of the patellar ligament at 40% strain increased from 19 kPa to 112 kPa and then decreased to 57 kPa. SEM observation showed that the cross-linking of collagen fibers was initially strengthened and then weakened. DSC results showed that the enthalpy increased from 59.47 J/g to 67.10 J/g and then decreased to 54.43 J/g. The denaturation temperature increased from 67.62 ℃ to 77.28 ℃ and then decreased to 64.10 ℃.Conclusions When rabbit patellar ligament is stored at -20 ℃, with the increase of storage duration, the compressive stress of rabbit patellar ligament at 40% strain increases at first and then decreases. This change may be due to the variation of cross-linking level of collagen fibers. The stronger the cross-linking of collagen fibers, the stronger the compressive mechanical properties will be.

Objective:To describe the baseline characteristics of the subjects enrolled in the China Quantitative CT (QCT) big data program in 2018—2019.Methods:Based on baseline data from the Chinese health big data project from January 2018 to December 2019 from the eligible enrolled population, measurements of bone mineral density (BMD) and visceral adipose tissue (VAT) were performed using Mindways′ QCT Pro Model 4 system. The baseline data of age, gender, regional distribution, height, weight, abdominal circumference, blood pressure, blood routine and blood biochemical tests were analyzed. And the single factor analysis of variance (ANOVA) was used to check the age related trend of BMD and VAT in both genders.Results:After screening the inclusion exclusion criteria and outliers of the main indicators, 86 113 people were enrolled in the project. The enrollment rate was 92.47%, including 35 431 (41.1%) women and 50 682 (58.9%) men, and the ratio of men to women was 1.43. The mean age was (50.3±12.7) years in all the subjects, and it was (50.2±12.8) years and (50.4±12.5) years in men and women, respectively, and there was no statistical difference between the two genders ( P>0.05). Total of 43 833 people were enrolled in east China, it was the largest group by region (50.90%), it was followed by central China (16 434 people, 19.08%), and the number of people enrolled in Northeast China was the lowest (2 914 people, 3.38%). The rate of completing of health information indicators related to the main outcome of the study were all above 70%, and there were significant differences between men and women (all P<0.05). The mean BMD was (139.33±46.76) mg/cm 3 in women, (135.90±36.48) mg/cm 3 in men, which showed a decreasing trend with age in both gender (both P<0.001); the mean intra-abdominal fat area was (116.39±56.23) cm 2 in women, (191.67±77.07) cm 2 in men, and there was an increasing trend with age in both men and women (both P<0.001). Conclusions:There are gender differences in BMD and VAT measured by QCT with different age tendency, and there are gender differences in health information index. Regional factors should also be taken into account for regional differences in the inclusion of data.

Objective:To investigate the normal reference values of spinal bone mineral density measured by quantitative computed tomography (QCT) and the differences of bone mineral density (BMD) in different regions of in Chinese adult males.Methods:Men who underwent low-dose CT lung scan for cancer screening in regions of Northeast, North, East, South, Central and Southwest of China from January 2018 to December 2019 were selected. And the lumbar vertebrae BMD values in the male subjects were measured by the QCT system (Mindways Software, Inc.). The mean BMD values and their decline rates were calculated at an age interval of 10 years, and the prevalence of osteoporosis was calculated according to the American College of Radiology spine QCT osteoporosis diagnostic criteria.Results:A total of 50 682 males with a mean age of (50.22±12.79) years (ranged 20 to 98 years) were included in this study. The peak BMD of (173.11±28.56) mg/cm 3 in the healthy Chinese adult male population appeared in the age group of 20 to 29 years and then declined with age. Before the age of 70 years, the BMD was relatively higher in males in South China, and it was lower in Central China and Southwest China, and it was intermediate in Northeast, North and East of China, with statistically significant differences. There was no significant differences in BMD in the males in the two age groups of 70 to 79 years and 80 and older among the regions in China. The overall decline rate of spinal BMD in Chinese males under QCT was about 46.92% over the lifetime, and it declined obviouslyin the 40-49 age group. The overall prevalence of osteoporosis in Chinese male population aged 50 years and above was approximately 11.42%, with the highest prevalence in Southwest China and Central China (14.72% and 13.87%, respectively) and the lowest in North China and South China (8.53% and 7.71%, respectively). Conclusions:A reference of lumbar spine BMD values for healthy males in China based on QCT is established. BMD values were highest in South China and Lowest in Central China.

Objective:To establish the normal reference value of lumbar bone mineral density (BMD) under quantitative CT (QCT) in Chinese healthy adult females and to explore the regional differences.Methods:Total of 35 431 healthy women who met the inclusion criteria of Chinese health quantitative CT big data program were selected in this study. The BMD of the central plane of L 1 and L 2 vertebrae was measured by Mindways′s QCT system, and the mean value was taken. One-way analysis of variance was used to compare the BMD differences of lumbar vertebrae in women of different ages and regions. The subjects were grouped by an age interval of 10 years, and the level of BMD in different regions of the same age group were compaired. Results:The peak BMD of Chinese healthy adult women appeared in the age group of 20-29 years (Northeast China(183.01±24.58) mg/cm 3, North China (188.93±24.80) mg/cm 3, East China (187.54±27.71) mg/cm 3, South China (186.22±33.72) mg/cm 3, Central China (176.33±24.91) mg/cm 3, Southwest China(182.25±28.00) mg/cm 3), and then it decreased with age. The level of BMD in different regions decreased with the age. Before the age of 70 years, BMD in Central and Southwest China was always at a low level((176.23±24.91) to (90.38±28.12) mg/cm 3, 182.25±28.00 to (88.55±25.68) mg/cm 3), lower than those in Northeast China ((183.01±24.58) to (99.69±27.85) mg/cm 3), North China ((188.93±24.80) to (95.89±26.12) mg/cm 3), East China ((187.54±27.71) to (95.65±27.86) mg/cm 3). After 70 years of age, BMD tended to be the same in different regions ( P>0.05). The BMD values in Central China and Southwest China were similar in the age group of 40-60 years ( P>0.05). The BMD values in the health adult femles in the age group of 60 years in different regions of Chinawere all lower than those of bone mass abnormality (all P<0.05). The detection rate of osteoporosis in females over 50 years was the highest in Southwest China (25.65%) and it was the lowest in North China (17.30%). Conclusions:This study establishes reference values of BMD under QCT in healthy Chinese women, which can be used as a reference basis for identifying women with low BMD who are at risk of osteoporosis. The BMD value is the lowest in Southwest China and the highest in South China.

Objective:To use quantitative computed tomography (QCT) technology to measure the bone mineral density of the spine of the Chinese healthy population, and to explore its correlation with hemoglobin and serum albumin.Methods:The data in this study came from the China Health Quantitative CT Big Data Project (China Biobank). The spine bone density was measured by using QCT Pro Image Analysis System and all cooperating centers used the European spine phantom (NO.145) for quality control. Total of 50 053 healthy persons who met the criteria for entry were selected as the research subjects. The subjects were divided into 7 groups according to age. The general data, spine bone density, serum albumin, hemoglobin of the subjects were collected. The single-factor analysis of variance, Pearson correlation analysis and multi-classification logistic regression model were applied to analyze the correlation between bone density and hemoglobin and serum albumin.Results:The bone mineral density of healthy people decreased with age ( P<0.05), and there were significant differences in hemoglobin, serum albumin and body mass index (BMI) among different age groups (all P<0.05). Linear correlation analysis showed that there were positive correlation between bone mineral density and hemoglobin in healthy males in different age groups ( r=0.086, 0.101, 0.076, 0.090, 0.072, 0.123, 0.100, all P<0.01). There were negative correlation between bone mineral density and hemoglobin in certain age groups in women (40-49 years group: r=-0.027; 70-79 yearsgroup: r=-0.077; both P<0.05). And corelation were found between bone mineral density and serum levels of albumin in certain age groups of healthy subjects (among men, 30-39 years group: r=-0.048; 40-49 years group, r=-0.027; 70-79 years group, r=-0.051; among women, 30-39 years group: r=-0.044; 40-49 years group, r=-0.042; 50-59 years group, r=-0.086; 70-79 years group, r=-0.070; all P<0.05). After adjusting for age and BMI, the multi-category logistic regression analysis showed that the hemoglobin level was protective factor of normal bone density ( OR=1.022, 95% CI:1.017-1.027) and decreased bone density ( OR=1.012, 95% CI:1.007-1.016) in healthy males, and the serum albumin was risk factor for normal bone density ( OR=0.926, 95% CI:0.905-0.948) and decreased bone density ( OR=1.006, 95% CI:0.951-1.011) in healthy women. Conclusion:There is a correlation between bone mineral density and hemoglobin and serum albumin in Chinese healthy population. Hemoglobin is a protective factor for bone mineral density in men, and serum albumin is a risk factor for bone mineral densityin women.

Objective:To investigate the value of renal artery resistance index (RRI) and urinary angiotensinogen (UAGT) in the early diagnosis of acute kidney injury (AKI) in patients with sepsis.Methods:A prospective study was conducted. Seventy-eight patients with sepsis admitted to the department of critical care medicine of General Hospital of Ningxia Medical University from January to September 2021 were enrolled. Patients were observed for the development of AKI within 1 week. General data [gender, age, body mass index (BMI), major infection sites and critical illness related scores], laboratory indicators [mean arterial pressure (MAP), central venous pressure (CVP), procalcitonin (PCT), arterial blood lactic acid (Lac), etc.], duration of mechanical ventilation and length of intensive care unit (ICU) stay were recorded. After hemodynamic stabilization of the patients, renal ultrasound was performed to measure the RRI within 24 hours after ICU admission. Urine samples were taken immediately after diagnosis, and the level of UAGT was detected by enzyme-linked immunosorbent assay (ELISA). The above parameters were compared between the two groups. Multivariate Logistic regression was used to analyze the risk factors of AKI in patients with sepsis. Receiver operator characteristic curve (ROC curve) was drawn to analyze the predictive value of related indicators for AKI in sepsis.Results:A total of 78 patients were finally enrolled, of which 45 developed AKI and 33 did not. Compared with the non-AKI group, the rates of vasoactive drugs use, 28-day mortality, sequential organ failure assessment (SOFA) score, acute physiology and chronic health evaluation Ⅱ (APACHEⅡ) score, PCT, Lac, RRI and UAGT were significantly higher in the AKI group [rates of vasoactive drugs use: 68.9% vs. 39.4%, 28-day mortality: 48.9% vs. 24.2%, SOFA score: 12.0 (10.5, 14.0) vs. 8.0 (7.0, 10.0), APACHEⅡ score: 22.0 (18.0, 27.5) vs. 16.0 (15.0, 18.5), PCT (μg/L): 12.5±2.6 vs. 10.9±2.8, Lac (mmol/L): 2.6 (1.9, 3.4) vs. 1.9 (1.3, 2.6), RRI: 0.74±0.03 vs. 0.72±0.02, UAGT (μg/L): 75.16±19.99 vs. 46.28±20.75, all P < 0.05], the duration of mechanical ventilation and the length of ICU stay were significantly prolonged [duration of mechanical ventilation (days): 8.0 (7.0, 12.0) vs. 5.0 (4.0, 6.0), length of ICU stay (days): 14.0 (10.0, 16.0) vs. 9.0 (8.0, 11.5), both P < 0.01], and MAP was significantly lowered [mmHg (1 mmHg ≈ 0.133 kPa): 68.5±11.2 vs. 74.2±12.8, P < 0.05]. There was no significant difference in other parameters between the two groups. Multivariate Logistic regression analysis showed that SOFA score [odds ratio ( OR) = 2.088, 95% confidence interval (95% CI) was 1.322-3.299], APACHEⅡ score ( OR = 1.447, 95% CI was 1.134-1.845), RRI ( OR = 1.432, 95% CI was 1.103-1.859), and UAGT ( OR = 1.077, 95% CI was 1.035-1.121) were independent risk factors for sepsis complicated with AKI (all P < 0.01). ROC curve analysis showed that SOFA score, APACHEⅡ score, RRI and UAGT had certain predictive value for AKI in septic patients, the area under the ROC curve (AUC) were 0.814 (95% CI was 0.716-0.912), 0.804 (95% CI was 0.708-0.901), 0.789 (95% CI was 0.690-0.888), and 0.840 (95% CI was 0.747-0.934), respectively, and the AUC of RRI combined with UAGT was 0.912 (95% CI was 0.849-0.974), which was better than the above single index (all P < 0.05). Conclusion:RRI combined with UAGT has a high early predictive value for septic AKI.

Objective:To investigate the relationship between abdominal visceral adipose tissue (VAT) and cardiometabolic risk (CMR) through quantitative computed tomography (QCT).Methods:The present study included 76226 participants. Abdominal fat areas were measured using the QCT Pro Model 4 system. Cardiometabolic indices were collected, including systolic and diastolic blood pressures, fasting plasma glucose, total cholesterol, triglyceride, and low-density and high-density lipoprotein cholesterols CMR score was the sum of abnormal blood pressure, fasting glucose, triglyceride, and high-density lipoprotein cholesterol. Restricted cubic spline and ordered logistic regression models were applied.Results:The mean age was 50±13 years and the percentage of men was 58.8%. The level of VAT area was higher in men than in women (191.7±77.1 cm 2 vs 116.4±56.2 cm 2, P<0.0001 for all). After adjustment for age, the cardiometabolic indices except high-density lipoprotein cholesterol increased with increasing VAT area. When VAT area was 300 cm 2, age-adjusted odds ratios and 95% confidence intervals of a CMR score ≥ 1 were 14.61 (13.31, 16.04) for men and 5.46 (4.06, 7.36) for women, and the age-adjusted probability of a CMR score ≥ 3 was 31.7% for men and 31.3% for women. Conclusions:QCT-derived VAT is closely related to CMR. The findings suggest that measurement of visceral fat is recommended for the management of abdominal obesity in subjects who agree to undergo lung cancer screening via low-dose CT without additional radiation exposure.

Objective To investigate the protective effect of carbon monoxide release molecule-2 (CORM-2) on intestinal barrier injury in shock rats. Methods Thirty-two rats were equally and randomly divided into 4 groups: the sham operated group, shock group, carbon monoxide releasing molecule-2 (CORM-2) group and inactivated CORM-2 (iCORM-2) group. A modified Wiggers model was used in inducing hemorrhagic shock. In the CORM-2 group and iCORM-2 group, the animals were intraperitoneally injected CORM-2 (5 mg/kg) or iCORM-2 (5 mg/kg) 1 h before inducing shock. The ileum tissues were harvested 24 h after operation or 24 h after inducing shock, and the histopathologic changes and ultrastructure of the ileum were observed. The expressions of ZO-1, Occludin, and Claudin3 protein in ileum intestinal mucosa were determined by Western blot. TNF-α and D-lactic acid levels in the blood were measured by enzyme-linked immunosorbent assay (ELISA). Data of multi-groups were analyzed by one way variance (ANOVA) and inter-group comparisons were made by the least significant difference (LSD)-t tests. Kruskal Wallis rank sum test was used when homogeneity of variance were not met. The value of P<0.05 was considered statistically significant. Results (1) The pathological changes and ultrastructural damage of ileum mucosa in the shock group were obvious. CORM-2 can significantly improve the pathological morphology and ultrastructural integrity of intestinal mucosa in shock rats. (2) Compared with the sham operated group, the expressions of Claudin3, Occludin, and ZO-1 of ileum intestinal mucosa were significantly decreased in the shock group and iCORM-2 group(all P<0.05), but in the CORM-2 group, only the expression of Claudin3 and ZO-1 were decreased(P<0.05). The expression of these proteins in the CORM-2 group was higher than that in the shock group and iCORM-2 group. (3) Compared with the sham operated group, the levels of D-lactic acid and TNF-α in the shock group and iCORM-2 group were significantly higher[D-lactic acid(ng/mL): 139.49 ± 28.83, 135.75 ± 25.19 vs 65.09 ± 33.16; TNF-α(pg/mL):358.60(314.18, 395.73),312.25(275.75, 345.40) vs 65.85(47.82, 84.32); all P<0.05], TNF-α value and D-lactic acid level showed increased trend in CORM-2 group, but it's not statistically significant[ D-lactic acid(ng/mL): 75.65±34.14 vs 65.09±33.16; TNF-α(pg/mL): 104.00(93.10, 131.95) vs 65.85(47.82, 84.32); all P>0.05]. The levels of D-lactic acid and TNF-αin the CORM-2 group were lower than those in the shock group and iCORM-2 group (all P<0.05). Conclusions CORM-2 may reduce the intestinal barrier damage by anti-inflammatory effects and up-regulate the expression of tight junction proteins in the intestinal epithelium.

Objective To explore the effects of nutritional supports following target energy measured by respiratory indirect calorimetry and HB coefficient method respectively on the nutrition and immune indexes of patients with sepsis. Methods A prospective comparative study of 60 patients with sepsis who was suitable for nutritional support and respiratory indirect calorimetry in the intensive care unit ( ICU) of the hospital from Jan-uary 2015 to October 2015 was conducted. Resting Energy Expenditure ( REE) was measured simultaneously by respiratory indirect calorimetry (n=30) and HB coefficient (Harris-Benedict formula×stress coefficient, n=30) in patients with sepsis and the nutritional support was given according to the MREE measured by the two methods. The nutritional and immune indexes were obtained at 0 day, 3 day, 7 day, and 14 day after nutritional support. The nutritional and immune indexes at 0 day were considered as the baseline and the differences in the nutritional and immune indexes between the baseline and 3 day, 7 day and 14 day were expressed as a "Δ". Values of Δ were compared between the two goups. Results With nutritional support for 3 days, Δalbumin,Δ prealbumin, Δthe total T lymphocytes, Δassist/induction of T cells and ΔIgG were higher in the respiratory indirect calorimetry group than in the HB coefficient group ( P<0. 05) . With nutritional support for 7 days, Δalbumin, ΔT lymphocytes, ΔIgM were higher in the respiratory indirect calorimetry group than in the HB coefficient group ( P<0. 05) . With nutritional support for 14 days, Δtransferrin, Δsuppression/cyto-toxic T cells, ΔIgG, ΔIgA, ΔC3 andΔC4 were higher in the respiratory indirect calorimetry group than in the HB coefficient group ( P<0. 05) . Conclusion Nutritional support with REE measured by respiratory in-direct calorimetry in patients with sepsis is more effective on nutritional and immune related indexes improve-ment have different degrees of improvement, thus respiratory indirect calorimetry is more suitable to guide the target energy of sepsis patients.

Objective To explore a new method for synthesizing arginine modified chitosan ( AC ) with mono-arginine substitution and high degree of substitution, and to evaluate the biological effect of AC as gene carriers. Methods The single arginine modified chitosan (sAC) was synthesized by means of protecting and de-protecting the arginine amino group before and after chitosan modified arginine reaction. Liu's arginine-modified chitosan ( LAC ) was prepared according to the methods reported in the literature . The conjunction of arginine to chitosan was detected by infrared spectroscopy and nuclear magnetic resonance spectroscopy. Three kinds of chitosan gene nanoparticles were respectively prepared by complex coacervation and characterized, including sAC gene nanoparticles (sACGNs), the LAC gene nanoparticles (LACGNs) and the chitosan gene nanoparticles (CGNs). A10 rat vascular smooth cells transfected with sACGNs were used to estimate the in vitro cellular uptake, internalization mechanisms and transfection efficiency. Thiazolyl blue tetrazolium blue (MTT) assay was used to measure the cytotoxicity. Results The infrared spectrum analysis confirmed that sAC was obtained via the conjunction of arginine to chitosan. Nuclear magnetic resonance spectrum analysis showed that the degree of substitution of arginine in sAC and LAC was 21.3％and 6.4％, respectively. When the ratio of nitrogen to phosphorus (N/P ratio) was 2:1, the particle sizes of CGN, LACGN, and sACGN were (94.81±2.93) nm, (124.53±2.55) nm, and (128.53±2.04) nm, respectively, and the Zeta potentials were (3.50±1.61) mV, (5.74±0.41) mV, and (6.04±1.39) mV, respectively. For the cellular uptake, CGNs were mainly through the clathrin-mediated endocytic pathway, and LACGNs and sACGN were mainly through the caveolin-mediated endocytic pathway. Compared with CGNs, LACGNs and sACGNs showed higher cellular uptake and transfection efficiency , and the differences were statistically significant ( all P<0 . 05 ) . sACGNs achieved the highest transfection efficiency in the near-neutral pH environment. MTT results showed that when the mass concentration of sACGNs reached 100μg/ml, the survival rate of A10 cells was still higher than 90％, indicating the non-cytotoxicity of sACGNs. Conclusion The new method successfully synthesized single arginine-modified chitosan. As a gene carrier, sACGNs show higher gene transfection efficiency and lower cytotoxicity than CGNs and LACGNs in near neutral pH environment.