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The loaded tooth contact analysis of cycloid pin wheel transmission mechanism of RV reducers is the basis of lubrication analysis of the mechanism. To clarify the dynamic contact characteristics between the cycloidal gear teeth and the needle teeth, as well as between the roller needles and the inner and outer rings of the crankshaft bearing, based on the meshing principle of the cycloidal needle gear transmission mechanism, the kinematic characteristics of the gear tooth clearance and meshing points under six different tooth profile modification methods are analyzed; combining the static equilibrium equation and deformation coordination conditions, the nonlinear Hertz contact stiffness is introduced and a three-dimensional dynamic load-bearing contact analysis model of the cycloidal needle gear transmission mechanism is established. The load deformation of the gear teeth with initial clearance is determined, and the model solution is completed using the iterative method. The time-varying force characteristics at the meshing of the gear teeth and the inner and outer rings of the crankshaft bearing roller needles during the transmission process are clarified.

Clinical failure of arteriovenous neointimal hyperplasia (NIH) fistulae (AVF) is frequently due to juxta-anastomotic NIH (JANIH). Although the mouse AVF model recapitulates human AVF maturation, previous studies focused on the outflow vein distal to the anastomosis. We hypothesized that the juxta-anastomotic area (JAA) has increased NIH compared with the outflow vein. AVF was created in C57BL/6 mice without or with chronic kidney disease (CKD). Temporal and spatial changes of the JAA were examined using histology and immunofluorescence. Computational techniques were used to model the AVF. RNA-seq and bioinformatic analyses were performed to compare the JAA with the outflow vein. The jugular vein to carotid artery AVF model was created in Wistar rats. The neointima in the JAA shows increased volume compared with the outflow vein. Computational modeling shows an increased volume of disturbed flow at the JAA compared with the outflow vein. Endothelial cells are immediately lost from the wall contralateral to the fistula exit, followed by thrombus formation and JANIH. Gene Ontology (GO) enrichment analysis of the 1,862 differentially expressed genes (DEG) between the JANIH and the outflow vein identified 525 overexpressed genes. The rat jugular vein to carotid artery AVF showed changes similar to the mouse AVF. Disturbed flow through the JAA correlates with rapid endothelial cell loss, thrombus formation, and JANIH; late endothelialization of the JAA channel correlates with late AVF patency. Early thrombus formation in the JAA may influence the later development of JANIH. NEW & NOTEWORTHY: Disturbed flow and focal endothelial cell loss in the juxta-anastomotic area of the mouse AVF colocalizes with acute thrombus formation followed by late neointimal hyperplasia. Differential flow patterns between the juxta-anastomotic area and the outflow vein correlate with differential expression of genes regulating coagulation, proliferation, collagen metabolism, and the immune response. The rat jugular vein to carotid artery AVF model shows changes similar to the mouse AVF model. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to compare the follow-up and outcomes of spontaneous isolated superior mesenteric artery dissection (SISMAD) in different angiographic types and to determine the optimal therapeutic options for SISMAD patients. Methods: This is a retrospective study of 61 SISMAD patients between December 2010 and January 2019 in a single center. Data analysis consisted of demographics, clinical data, radiology review, treatment, follow-up, and outcomes. Results: A total of 61 SISMAD patients were reviewed in this study. Median age was 53 (quartile, 47.5–63.0), 90.2% were males with hypertension (50.8%), dyslipidaemia (54.1%), and smoking history (60.7%). Among all, 43 patients underwent periodic follow-up of computed tomography (CT) angiography for follow-up analysis. 11 (25.6%) patients showed "No Change" during follow-up, including 6 type I patients. 23 patients (53.5%) were "Partially Remodelled" and 18 of them were type II patients. 7 "Completely Remodelled" patients (16.3%) were all in type II group. Two type III patients (4.6%) died after the emergent surgical intervention within 30 days. Conclusions: Different SISMAD angiographic types present with variant progression. Type I SISMAD may be inclined to remain "unchanged." Type II SISMAD shows a clear trend to remodeling, especially type IIb patients. The progression of type III SISMAD varies in the extent of collateral bypasses. [ABSTRACT FROM AUTHOR]

We aimed to establish an animal model of abdominal aortic vascular replacement in mongrel dogs to investigate the effect of extracorporeal radiotherapy on the intima. Twenty healthy mongrel dogs were randomly divided into four groups: 5-week control group, 5-week radiotherapy group, 10-week control group and 10-week radiotherapy group. We first performed an artificial vascular replacement of the abdominal aortic segment. The radiotherapy group received external radiotherapy with a dose of 7 Gy for 4 days. The thickness of neointimal hyperplasia, immunoreactivity and expression of proliferation-related factors were detected by hematoxylin and eosin (HE) staining, immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR)and western blotting at 5 and 10 weeks after the reconstruction. The results showed that the intimal thickness of the artificial blood vessel in the 5- and 10-week radiotherapy groups was thinner than that in the control groups by HE staining. The immunoreactivity and expression levels of Skp2, c-Myc and CyclinE1 were significantly decreased in the radiotherapy groups than those in control groups by immunohistochemistry, qRT-PCR and western blotting. On the contrary, immunoreactivity and expression levels of P27kip1 were increased. In conclusion, we discovered that postoperative external radiotherapy significantly decreases the intimal hyperplasia of artificial blood vessels by regulating c-Myc-Skp2-P27-CyclinE1 network. [ABSTRACT FROM AUTHOR]

We identified changes in renal function in patients who underwent thoracic endovascular aortic repair (TEVAR) and the factors that may influence renal function. Information on 470 consecutive patients was collected. Kidney function and contrast volume were recorded. Unpaired t test, Spearman correlation, and logistic regression were used for statistical analysis. A Kaplan-Meier curve helped clarify our follow-up findings. Mean contrast volume was 90.5 ± 21.2 mL. The change in serum creatinine was significantly correlated with (1) preexisting renal pathology (P =.033) and (2) aortic dissection (AD) involving the renal arteries (P =.019). The change in serum urea nitrogen (ΔBUN) was only significantly correlated with AD involving the renal arteries (P =.0348). Contrast volume (P =.036, odds ratio = 1.010, 95% confidence interval: 1.001-1.019) was a risk factor for contrast-induced nephropathy (CIN) after TEVAR. Survival rates and renal failure rates among no CIN, CIN, and CIN–acute kidney injury groups at longest 27 months follow-up were significantly different. Creatinine and BUN were generally elevated post-TEVAR. Contrast-induced nephropathy post-TEVAR may correlate with renal comorbidities and renal artery involvement. Contrast volume is risk factor for CIN after TEVAR. More attention needs to be paid to patient renal function during follow-up. [ABSTRACT FROM AUTHOR]