OBJECTIVETo establish an accurate new rat model of hyperammonemia-induced liver injury for use in studies of the molecular mechanisms underlying acute liver failure (ALF).

METHODSTwenty-six Sprague-Dawley rats were administered D-galactosamine (400 mg/kg) and endotoxin (50 mug/kg) via intraperitoneal injection to induce ALF and sacrificed at 12 h post-injection (ALF-12 group, n = 10) or 24 h post-injection (ALF-24 group, n = 16). Ten rats administered physiological saline served as the control group. In addition, 20 rats were given serial oral administrations of 10% NH4Cl solution (10 ml/kg, every 8 hrs) to establish the hyperammonemia-induced liver injury model; an additional 20 rats were prepared in parallel to serve as the ALF control group (n = 10; D-galactosamine at 800 mg/kg every 6 d for 30 days) and the physiological saline control group (n = 10). Serum samples were collected from each mouse and used to detect markers of liver function, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alpha-fetal protein (AFP), and gamma-glutamyltransferase (GGT), as well as blood ammonia (BA) level and prothrombin time activity (PT-A). Affects on liver histology was assessed by hematoxylin and eosin staining of resected liver tissues, and on apoptosis by TUNEL assay and calculating the apoptotic index (AI).

RESULTSALF rats showed elevated levels of ALT (1202.51+/-282.00 U/L), AST (1560.14+/-298.98 U/L), and BA (165.9+/-23.6 mumol/L) as early as 6 hrs after model establishment; these levels peaked at 12 hrs after model establishment (ALT: 774.40+/-207.65 U/L; AST: 967.60+/-121.94 U/L; BA: 143.4+/-18.1 mumol/L; P less than 0.05). No significant variations were detected in the levels of AFP (except for the ALF-24 group) or GGT. Liver tissues of the ALF-12 and ALF-24 groups showed large or diffuse hemorrhagic necroses with sinusoidal congestion or spotty bleeding, as well as increased AI. Hyperammonemia-induced liver injury rats showed elevated levels of ALT and BA as early as 6 hrs after model establishment. Similar to the ALF rats, AFP and GGT were unaffected and AI increased. However, in contrast to the ALF rats, the liver tissues of the hyperammonemia-induced liver injury rats showed no signs of hepatocyte swelling, necrosis, or inflammatory cell invasion.

CONCLUSIONALF rats and hyperammonemia-induced liver injury rats have elevated BA and marked hepatocyte necrosis. Given that reducing the level of ammonemia can improve the animal's biochemistry indexes, it is likely that hyperammonemia plays a role in acute liver injury or ALF consequent to repeated injury. The pathogenic mechanisms of repeated injury may involve promotion of hepatocyte apoptosis in conjunction with inhibition of cellular regeneration.

Animals ; Disease Models, Animal ; Hyperammonemia ; complications ; Liver Failure, Acute ; etiology ; Male ; Rats ; Rats, Sprague-Dawley

Objective To explore early postoperative gait characteristics and clinical outcomes after total knee arthroplasty(TKA).Methods From February 2023 to July 2023,26 patients with unilateral knee osteoarthritis(KOA)were treated with TKA,including 4 males and 22 females,aged from 57 to 85 years old with an average of(67.58±6.49)years old;body mass in-dex(BMI)ranged from 18.83 to 38.28 kg·m-2 with an average of(26.43±4.15)kg·m-2;14 patients on the left side,12 pa-tients on the right side;according to Kellgren-Lawrence(K-L)classification,6 patients with grade Ⅲ and 20 patients with grade Ⅳ;the courses of disease ranged from 1 to 14 years with an average of(5.54±3.29)years.Images and videos of standing up and walking,walking side shot,squatting and supine kneeling were taken with smart phones before operation and 6 weeks after operation.The human posture estimation framework OpenPose were used to analyze stride frequency,step length,step length,step speed,active knee knee bending angle,stride length,double support phase time,as well as maximum hip flexion angle and maximum knee bending angle on squatting position.Western Ontario and McMaster Universities(WOMAC)arthritis index and Knee Society Score(KSS)were used to evaluate clinical efficacy of knee joint.Results All patients were followed up for 5 to 7 weeks with an average of(6.00±0.57)weeks.The total score of WOMAC decreased from(64.85±11.54)before op-eration to(45.81±7.91)at 6 weeks after operation(P＜0.001).The total KSS was increased from(101.19±9.58)before opera-tion to(125.50±10.32)at 6 weeks after operation(P＜0.001).The gait speed,stride frequency and stride length of the affected side before operation were(0.32±0.10)m·s-1,(96.35±24.18)steps·min-1,(0.72±0.14)m,respectively;and increased to(0.48±0.11)m·s 1,(104.20±22.53)steps·min-1,(0.79±0.10)m at 6 weeks after operation(P＜0.05).The lower limb support time and active knee bending angle decreased from(0.31±0.38)sand(125.21±11.64)° before operation to(0.11±0.04)s and(120.01±13.35)° at 6 weeks after operation(P＜0.05).Eleven patients could able to complete squat before operation,13 patients could able to complete at 6 weeks after operation,and 9 patients could able to complete both before operation and 6 weeks after operation.In 9 patients,the maximum bending angle of crouching position was increased from 76.29° to 124.11° before operation to 91.35° to 134.12° at 6 weeks after operation,and the maximum bending angle of hip was increased from 103.70° to 147.25° before operation to 118.61° to 149.48° at 6 weeks after operation.Conclusion Gait analysis technology based on artificial intelligence image recognition is a safe and effective method to quantitatively identify the changes of pa-tients'gait.Knee pain of KOA was relieved and the function was improved,the supporting ability of the affected limb was im-proved after TKA,and the patient's stride frequency,stride length and stride speed were improved,and the overall movement rhythm of both lower limbs are more coordinated.