[Correlation between osteopontin and cartilage oligomeric matrix protein levels in joint synovial fluid of patients with knee osteoarthritis and disease severity].

OBJECTIVE: To investigate the correlation between osteopontin(OPN) and cartilage oligomeric matrix protein (COMP) levels in synovial fluid of patients with knee osteoarthritis(KOA) and the severity of the disease. METHODS: A total of 59 patients with KOA admitted to our hospital from February 2018 to May 2020 were selected as the KOA group, including 25 males and 34 females, age ranged 60 to 75 years old with an average of(65.57±1.56) years old, the body mass index(BMI) ranged 21.4 to 30.7(26.12±1.54) kg/m2. After admission, X-ray examination was performed, and Kellgren-Lawrence(K-L) grading system was used to evaluate the X-ray examination results. There were 14 cases in gradeⅡ(K-L2 group), 27 cases in grade Ⅲ(K-L3 group), and 18 cases in grade Ⅳ(K-L4 group). Eighteen patients who underwent arthroscopy for ligament or meniscus disease without cartilage damage were selected as control group, including 7 males and 11 females, age ranged 61 to 78 years old with an average of (64.88±1.60) years old, BMI ranged 22.8 to 29.9(25.89±1.49) kg/m2. Before treatment, synovial fluid samples of subjects were collected, and the OPN and COMP levels of synovial fluid were detected by Elisa. The OPN and COMP levels of synovial fluid in KOA group and control group were compared. The clinical data of KOA patients with different K-L grades were collected, including gender, age and BMI. The biochemical indices of interleukin-1 ß(IL-1ß), OPN, COMP and matrix metalloproteinase 3(MMP-3) in synovitic fluid were detected by enzyme-linked immunoassay, and the clinical data and biochemical indices of KOA patients with different K-L grades were compared. Logistic regression was used to analyze the factors affecting the K-L classification of KOA patients, and the area under the ROC curve(AUC) was used to predict the severity of KOA. RESULTS: All the 59 patients were followed up for 8 to 27(15.75±3.27) months. The levels of OPN and COMP in synovial fluid in KOA group were significantly higher than those in control group (t=16.991, 17.387, P<0.001). The levels of IL-1ß, OPN, COMP and MMP-3 in synovitic fluid were significantly different among those in different K-L grade KOA patients(P<0.001). Compared with the K-L2 group, the levels of IL-1ß, OPN, COMP, and MMP-3 in the synovial fluid of K-L3 and K-L4 were increased (P<0.05). Compared with the K-L3 group, the levels of IL-1ß, OPN, COMP, and MMP-3 in the K-L4 joint were increased (P<0.05). Multivariate Logistic regression analysis showed that the levels of OPN, COMP and MMP-3 were independent risk factors for K-L grading of KOA patients(OR=6.653, 4.229, 1.579, P<0.001). AUC of OPN in synovial fluid predicting K-L4 KOA was 0.720[95%CI(0.588-0.851)], and the sensitivity was 94.4%. the specificity was 65.9%. The AUC of COMP in synoviac fluid predicting K-L4 KOA was 0.731[95%CI(0.592-0.870)], the sensitivity was 88.9%, the specificity was 63.4%. The AUC of OPN combined with COMP in synoviac fluid predicting K-L4 KOA was 0.839 [95%CI(0.724-0.953)], the sensitivity was 94.4%, and the specificity was 51.2%. The AUC of OPN combined with COMP in synoviac fluid predicting K-L4 grade KOA was greater than that of OPN and COMP alone(Z=4.037, 3.540, P<0.05). CONCLUSION: The levels of OPN and COMP in synovial fluid increase in patients with KOA, and they increase with the increase of K-L grade. Synovitic fluid OPN and COMP are independent risk factors affecting K-L grade of KOA patients, and they have high AUC, sensitivity and specificity in predicting of K-L4 KOA, and can be used to evaluate the progression of KOA disease.

Forensic analysis on bursting accident of buffer tank in liquefied natural gas bus.

In December 2019, a buffer tank burst accident occurred in the maintenance of liquefied natural gas (LNG) bus in China. Failure analysis revealed the bus-mounted buffer tank had been subjected to an excessive internal pressurization, although the tank material met the specifications for engineering practice. The physical evidence related to the failed tank showed that a chemical explosion was impossible. As water was used to pouring the frozen pipeline prior to the accident, according to the consequences observed, the rapid phase transition (RPT) explosion of the residual LNG due to external heat from water was regarded as the main causation of incident. The explosion energy was inversely estimated by the TNT equivalent method, and the rapid expansion of natural gas produced excessive pressure, thus causing the buffer tank to explode.

Submicrometer aluminum spheres' adhesion to planar silicon substrates.

We investigate the adhesion mechanism of aluminum spheres on a silicon substrate. Aluminum particles in the size range of 60-1500 nm were deposited onto a silicon substrate. It was found that aluminum particles underwent plastic deformation rather than elastic deformation because of van der Waals interactions. A finite element model developed recently is also used to analyze our results. Because the MP model was proposed to describe plastic deformation based on an analysis of metal microcontacts, our results prove the correctness of the MP model from its origin and basis of arguments.

Contact between submicrometer silica spheres.

Recently, the scope of the investigation of the deformation mechanism extended to the micrometer and submicrometer regimes. The sphere-substrate contact method was usually used because it is rather difficult to make two micrometer or submicrometer spheres contact each other precisely. Here, we used the sphere-sphere contact method via a novel, simple process to investigate the deformation of spheres. The silica particle size ranges from 400 to 900 nm. Traditionally, the harder the particle, the smaller both the contact radius and the adhesion force. Therefore, it is widely accepted that silica particles should undergo elastic deformation, but we found that silica particles underwent plastic deformation rather than elastic deformation because of van der Waals interaction. The contact radii were observed by scanning electron microscopy (SEM).

Preparation of spherical silica particles by Stöber process with high concentration of tetra-ethyl-orthosilicate.

In this paper, Stöber process with high concentration of tetra-ethyl-orthosilicate (TEOS) up to 1.24 M is used to prepare monodisperse and uniform-size silica particles. The reactions are carried out at [TEOS]=0.22-1.24 M, low concentrations of ammonia ([NH(3)]=0.81[TEOS]), and [H(2)O]=6.25[TEOS] in isopropanol. The solids content in the resulting suspension achieves a maximum value of 7.45% at 1.24 M TEOS. Various-sized particles in the range of 30-1000 nm are synthesized. The influences of TEOS, NH(3), and H(2)O on the size and size distribution of the particles are discussed. A modified monomer addition model combined with aggregation model is proposed to analyze the formation mechanism of silica particles.

[Tetramethylpyrazine accelerated spinal cord repair through regulation of caspase-3 and neurofilament protein expression: an acute spinal cord injury model in rats].

OBJECTIVE: To investigate the effect of tetramethylpyrazine on spinal cord repair through hypothesized pathways including regulation of caspase-3, neurofilament protein NF-L, NF-H, and NF-M expression. METHODS: Allenos weight drop method was used to establish acute spinal cord injury (SCI) rat model at T10 section and was conducted in 80 adult Sprague Dawley rats that were subsequently divided into pseudo-therapy group (sodium chloride group, n=40) and tetramethylpyrazine group (treatment group, n=40). Eight normal rats were included into the pseudo-surgery normal group (n=1 for each time point). The function of spinal cord was evaluated with animal behavioral scores by measuring modified Rivilin loxotic plate degree and counting BBB score at 1, 3, 7, 14, and 21 d postoperatively. The injured spinal cord tissue samples were harvested at 1 h, 3 h, 6 h, 1 d, 3 d, 7 d, 14 d, and 21 d postoperatively (n=5 for each time point) for the preparation of continuous histological sections that were analyzed the expression of caspase-3,NF-L,NF-H, and NF-M by immunohistochemistry method. RESULTS: At postoperative Day 7, 14, and 21, animal behavioral scores revealed higher modified Rivlin loxotic plate degree and BBB scores in the treatment group when compared with those of the control group (P<0.05). The cells in the injured spinal cord tissue expressed significantly less caspase-3 and significantly more NF (NF-L, NF-H and NF-M) in the treatment group than those in the control group at Day 3, 7, and 14 (P<0.05). There was positive correlation between modified Rivlin loxotic plate degree and NF expression, BBB score and NF expression; and negative correlations between BBB score and caspase-3 expression, caspase-3 expression and NF expression. CONCLUSION: Tetramethylpyrazine improves spinal cord healing through regulation of caspase-3 and neurofilament protein expression.