Experimental Intestinal Stenosis Alters Crohn's Disease-Like Intestinal Inflammation in Ileitis-Prone Mice.

BACKGROUND: Clinical observations indicate that mechanical factors contribute to the expression or recurrence of Crohn's disease. We investigated whether the creation of an intestinal stenosis could alter the severity of the expected Crohn-like ileitis, in a Crohn's disease animal model, the TNFΔare/+ mouse. METHODS: Thirty-six, 6-weeks-old TNFΔare/+ mice, were divided into 3 intervention groups: triple suture, single suture and sham. In the terminal ileum, in the first group, a triple suture stenosis was created, whereas, in the second, a loose suture was placed. Same triple-suture stenosis was performed on twelve wild type mice. All animals were sacrificed at 6 weeks post-operatively and the ileum parts were evaluated histopathologically. A summative total ileitis score was applied in each sample using a bespoke semiquantitative histological scoring system for the Crohn-like changes. RESULTS: The triple suture stenosis induced significant muscular hypertrophy proximal to interventional site which was more prominent in TNFΔare/+ than wild type mice. In triple suture group, the total ileitis score was significantly increased proximal to the intervention as compared to the single suture (P: 0.004) and the sham groups (P: 0.013). The total ileitis score distally, was unaffected, regardless of the experimental intervention. Intestinal stenosis did not induce intestinal inflammation in wild type mice. CONCLUSION: The creation of a stenosis in the terminal ileum of TNFΔare/+ mice alters Crohn-like inflammation. We assume that mechanical forces, such as intraluminal pressure, may contribute as important co-factors to the pathophysiology of Crohn's disease in genetically predisposed subjects.

Mechanical factors and mechanism of keratoconus pathogenesis / 国际眼科杂志(Guoji Yanke Zazhi)

Keratoconus is a corneal ectatic disease characterized by progressive corneal thinning and protrusion. Its pathogenesis remains unclear. In vitro experiments have shown that mechanical stimulation may damage corneal stromal cells by increasing oxidative stress level and inflammatory factor concentration, resulting in a series of changes such as degradation of corneal extracellular matrix. Numerous clinical studies have confirmed that mechanical factors, including eye rubbing and eyeball compression caused by sleeping position, may play an important role in the process of keratoconus occurrence and development. They may affect the cornea by increasing the level of inflammatory factors in tear, causing changes in intraocular pressure, changing the biomechanical properties of the cornea, directly damaging corneal tissue by mechanical friction, and increasing the temperature of corneal epithelium. The main aim of this review was to describe the efforts of mechanical factors on corneal stromal cells, corneal tissue, and the possible role of mechanical factors in the pathogenesis of keratoconus, so as to provide a reference for the prevention and management of keratoconus.

Research Progress in Effects of Mechanical Factors on Angiogenesis of Vascular Endothelial Cells and the Mechanism / 医用生物力学

The angiogenic capacity of vascular endothelial cells is influenced by multiple mechanical factors. Mechanical factors guide the rearrangement of cytoskeleton, mediate intracellular signal transduction, affect cell migration, orientation and other behaviors, and then regulate their angiogenic capacity. However, different types of mechanical stimulation have different effects on their angiogenic capacity. This article summarizes and discusses the research work and progress of the influence of five mechanical factors （shear force, stretch stress, low-intensity pulsed ultrasound, microgravity, material properties） on vascular endothelial cell angiogenesis, which provides a basis and ideas for in-depth research of vascular biomechanics.

Biological and Mechanical Factors Promote the Osteogenesis of Rabbit Artificial Vertebral Laminae: A Comparison Study.

Reconstruction of vertebral laminae without epidural scar formation has been challenging. The success of bone formation depends on the biological and mechanical conditions of the surrounding tissues. In this study, we aimed to investigate the roles of biological and mechanical factors in the osteogenesis of artificial laminae. Mesenchymal stem cells derived from rabbit umbilical cord Wharton's jelly were induced for osteogenic differentiation for 3 weeks before seeding on the hydroxyapatite-collagen I scaffolds to construct the tissue-engineered laminae (TEL). TEL were then implanted into the fifth rabbit lumbar vertebrae in both orthotopic lamina (n = 30) and ectopic lamina (n = 30) groups. De novo laminae were examined through histological and radiographic analysis in the 2nd, 4th, 8th, 12th, and 16th weeks postimplantation. Our results showed that de novo laminae formed effectively in both groups, and the osteogenic gene expression levels and cancellous microstructure parameters of de novo laminae in the orthotopic lamina group were significantly higher than those in the ectopic lamina group. In conclusion, the biological stimulation of bone defect initiated the early onset osteogenesis, and the mechanical stimulation of cerebrospinal fluid pulsation stress promoted the osteogenesis of de novo laminae.

Mechanical factors and vitamin D deficiency in schoolchildren with low back pain: biochemical and cross-sectional survey analysis.

OBJECTIVE: This study was designed to evaluate the role of vitamin D, muscle fatigue biomarkers, and mechanical factors in the progression of low back pain (LBP) in schoolchildren. BACKGROUND: Children and adolescents frequently suffer from LBP with no clear clinical causes, and >71% of schoolchildren aged 12-17 years will show at least one episode of LBP. MATERIALS AND METHODS: A total of 250 schoolchildren aged 12-16 years were randomly enrolled in this study. For all schoolchildren height, weight, percentage of daily sun exposure and and areas of skin exposed to sun, method of carrying the bag, and bag weight and type were recorded over a typical school week. Pain scores, physical activity (PA), LBP, serum vitamin 25(OH)D level, serum bone-specific alkaline phosphatase, creatine kinase (CK), and lactate dehydrogenase (LDH) activities and calcium (Ca) concentrations were estimated using prevalidated Pain Rating Scale, modified Oswestry Low Back Pain Disability Questionnaire, short-form PA questionnaire, and colorimetric and immunoassay techniques. RESULTS: During the period of October 2013-May 2014, LBP was estimated in 52.2% of the schoolchildren. It was classified into moderate (34%) and severe (18%). Girls showed a higher LBP (36%) compared with boys (24%). In schoolchildren with moderate and severe LBP significantly higher (P=0.01) body mass index, waist, hip, and waist-to-hip ratio measurements were observed compared with normal schoolchildren. LBP significantly correlated with less sun exposure, lower PA, sedentary activity (TV/computer use), and overloaded school bags. In addition, schoolchildren with severe LBP showed lower levels of vitamin 25(OH)D and Ca and higher levels of CK, LDH, and serum bone-specific alkaline phosphatase compared with moderate and healthy schoolchildren. Stepwise regression analysis revealed that age, gender, demographic parameters, PA, vitamin D levels, Ca, CK, and LDH associated with ~56.8%-86.7% of the incidence of LBP among schoolchildren. CONCLUSION: In children and adolescents, LBP was shown to be linked with limited sun exposure, inadequate vitamin D diets, adiposity, lower PA, sedentary lifestyles, vitamin 25 (OH) D deficiency, and lower levels of Ca, CK, and LDH.

Factors influencing the end of the service life of protective gloves used in car repair shops: a preliminary report.

The paper presents the results of an end-of-service-life study on 2 kinds of protective gloves designed for workplaces in which workers are exposed to mineral oils and mechanical factors. The authors developed their own end-of-service-life study method that takes into account factors occurring during real-life use of protective gloves. The examined gloves were subjected to mechanical, chemical, and physical factors. The objective of the study was to compare the protective in new gloves subjected to a laboratory simulation test and in gloves used at workplaces in car repair shops. A further goal was to design a glove assessment procedure that would ensure comprehensive analysis of the actual level of performance provided by gloves exposed to selected chemical and mechanical factors as well as subjected to the influence of temperature and humidity, mechanical damage, and chemical degradation of material. The results lead to the conclusion that simultaneous exposure of protective gloves to mechanical, chemical, and physical factors significantly decreases their performance levels. Furthermore, similar performance levels were obtained for gloves subjected to laboratory simulation tests and for those used in the workplace.

The role of mechanical stress in the pathogenesis of spondyloarthritis and how to combat it.

Given that entheses are sites of high mechanical stress that concentrate the forces of large contracting muscles down onto a small footprint of bone contact, it was recognized nearly 60 decades ago that stress and injury at such sites may play a role in the pathogenesis of mechanically related enthesopathy. In recent years, the role of mechanical stress and its related consequences on inflammatory enthesitis have also been recognized. Clinical imaging studies and experimental animal models of spondyloarthropathy including tumor necrosis factor (TNF) transgenic models and interleukin (IL)-23 overexpression systems are associated with a primary enthesitis with disease subsequently spreading to adjacent joint structures including the synovium and bone. Joint mechanical stress, without discernible microdamage or injury, leads to spondyloarthritis (SpA) in a TNF transgenic model. Normal-aged human entheses often demonstrate microdamage, but it is unclear whether an abnormal response to mechanical stress alone or the need for stress-induced microdamage is involved in human disease initiation. Clinically, the contribution of mechanical stress to SpA including psoriatic arthritis (PsA) helps conceptualize the disease in a new way and provides obvious mechanistic links to skin and nail Koebner responses. It also offers novel epidemiological explanations for why PsA develops in subjects with high body mass indices most typically in the fourth and fifth decades. Molecularly, the monogenic forms of SpA including caspase recruitment domain-containing protein 14 (CARD14) and IL36RN mutations have site-specific expression of mutated proteins in the skin, thus offering a direct molecular link between local inflammation-related pathway dysregulation and local stress or injury in disease causation. Given that many of the pathways that govern both immunity and mechanical stress including extracellular-signal-regulated kinase (ERK) and mitogen-activated protein kinase (MAPK) are shared, it may be difficult to develop strategies that selectively target mechanical stress-related pathways. However, occupational- and obesity-related factors may be potentially modifiable in susceptible individuals to prevent or ameliorate disease.

Prediction of Force on the Spine Using Three-Dimensional Mathematical Model / 대한척추외과학회지

Mechanical factors in the human body are considered to play a dominant role in low back pain problems. Various spinal structures, including muscles, act in unison to resist the external load. An estimation of the muscle forces in this structure requires a knowledge of the orientation, location and area of cross-section of the muscles to complete the formulation of a truly threedimensional mathematical model of the spine. The geometric parameters which are calculated were the line of action, the centroid and physiologic area of cross-section of each muscle as a function of the spinal level. This geometric data were obtained from CT scans of 11 subjects participating in this study.