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Backgorund: The development of vibration-induced finger disorders is likely associated with combined static and dynamic responses of the fingers to vibration exposure. To study the mechanism of the disorders, a new rat-tail model has been established to mimic the finger vibration and pressure exposures. However, the mechanical behavior of the tail during compression needs to be better understood to improve the model and its applications., Objective: To investigate the static and time-dependent force responses of the rat tail during compression., Methods: Compression tests were conducted on Sprague-Dawley cadaver rat tails using a micromechanical system at three deformation velocities and three deformation magnitudes. Contact-width and the time-histories of force and deformation were measured. Additionally, force-relaxation tests were conducted and a Prony series was used to model the force-relaxation behavior of the tail., Results: The rat tails' force-deformation and stiffness-deformation relationships were strongly nonlinear and time-dependent. Force/stiffness increased with an increase in deformation and deformation velocity. The time-dependent force-relaxation characteristics of the tails can be well described using a Prony series., Conculsions: We successfully quantified the static and time-dependent force responses of rat tails under compression. The identified mechanical behavior of the tail can help improve the rat-tail model and its applications.

Background: Wearing protective helmets is an important prevention strategy to reduce work-related traumatic brain injuries. The existing standardized testing systems are used for quality control and do not provide a quantitative measure of the helmet performance., Objective: To analyze the failure characterizations of Type I industrial helmets and develop a generalized approach to quantify the shock absorption performance of Type I industrial helmets based on the existing standardized setups., Methods: A representative basic Type I construction helmet model was selected for the study. Top impact tests were performed on the helmets at different drop heights using two different impactor masses (3.6 and 5.0 kg)., Results: When the helmets were impacted with potential impact energies smaller than the critical potential impact energy values, there was a consistent relationship between the peak impact force and the potential impact energy. When the helmets were impacted under potential impact energies greater than the critical potential impact energy values, the peak impact forces increased steeply with increasing potential impact energy., Conclusion: A concept of safety margin for construction helmets based on potential impact energy was introduced to quantify the helmets' shock absorption performance. The proposed method will help helmet manufacturers improve their product quality.

Background: The use of helmets was considered to be one of the important prevention strategies employed on construction sites. The shock absorption performance of a construction (or industrial) helmet is its most important performance parameter. Industrial helmets will experience cumulative structural damage when being impacted repeatedly with impact magnitudes greater than its endurance limit., Objective: The current study is to test if the shock absorption performance of Type I construction helmets subjected to repeated impacts can be improved by applying polyethylene air-bubble cushions to the helmet suspension system., Methods: Drop impact tests were performed using a commercial drop tower test machine following the ANSI Z89.1 Type I drop impact protocol. Typical off-the-shelf Type I construction helmets were evaluated in the study. A 5 mm thick air-bubble cushioning liner was placed between the headform and the helmet to be tested. Helmets were impacted ten times at different drop heights from 0.61 to 1.73 m. The effects of the air-bubble cushioning liner on the helmets' shock absorption performance were evaluated by comparing the peak transmitted forces collected from the original off-the-shelf helmet samples to the helmets equipped with air-bubble cushioning liners., Results: Our results showed that a typical Type I construction helmet can be subjected to repeated impacts with a magnitude less than 22 J (corresponding to a drop height 0.61 m) without compromising its shock absorption performance. In comparison, the same construction helmet, when equipped with an air-bubble cushioning liner, can be subjected to repeated impacts of a magnitude of 54 J (corresponding to a drop height 1.52 m) without compromising its shock absorption performance., Conclusions: The results indicate that the helmet's shock absorbing endurance limit has been increased by 145% with addition of an air-bubble cushioning liner.

The rehabilitation squeeze ball is a popular device to help strengthen the hand, fingers and forearm muscles. The distributions of the contact pressure in the interface between the therapy ball and hand/fingers can affect the joint moment of each of the individual fingers, thereby affecting rehabilitation effects. In the current study, we evaluated the contact force distributions on the fingers when gripping a spherical object. Eight female adults [age 29 (9.1) years, mass 64.6 (7.1) kg, height 163.5 (1.9) cm, hand length 17.2 (0.7) cm] participated in the study. Contact force sensors were attached to the middle of the palmar surfaces of the distal, middle, and proximal phalanges of the four fingers in the longitudinal direction. In order to evaluate the effects of the ball stiffness on the contact force distributions on the fingers, subjects were requested to perform quasi-static gripping on a standard tennis ball and on a rehabilitation ball. The tennis ball is much stiffer and experiences smaller deformation under compression compared to the rehabilitation ball. We analyzed the force share among the distal, middle, and proximal finger segments, when subjects gripping balls of different stiffnesses (tennis ball vs. rehabilitation ball) and at three different grip efforts. Our results indicated that the grip force is contributed about 60% and 40% by the middle/ring fingers and by the index/little fingers, respectively. These characteristics are independent of the grip force levels and stiffness of the contact surface.

The finite element (FE) method has been widely used to investigate the mechanism of traumatic brain injuries (TBIs), because it is technically difficult to quantify the responses of the brain tissues to the impact in experiments. One of technical challenges to build a FE model of a human head is the modeling of the cerebrospinal fluid (CSF) of the brain. In the current study, we propose to use membrane elements to construct the CSF layer. Using the proposed approach, we demonstrate that a head model can be built by using existing meshes available in commercial databases, without using any advanced meshing software tool, and with the sole use of native functions of the FE package Abaqus. The calculated time histories of the intracranial pressures at frontal, posterior fossa, parietal, and occipital positions agree well with the experimental data and the simulations in the literature, indicating that the physical effects of the CSF layer have been accounted for in the proposed modeling approach. The proposed modeling approach would be useful for bioengineers to solve practical problems.

The prognostic value of HER2 has been demonstrated in many human cancer types such us breast cancer, gastric cancer and ovarian cancer. Trastuzumab is the first anti-HER2 monoclonal antibody that has remarkably improved outcomes of patients with HER2-positive breast cancer. For HER2-positive metastatic gastric cancers, the addition of trastuzumab to traditional chemotherapy also significantly prolonged overall survival. However, intrinsic and acquired resistance to trastuzumab is common and results in disease progression. HER2 signaling network and mechanisms underlying the resistance have been broadly investigated in order to develop strategy to overcome the dilemma. Increasing evidence indicates that microRNAs (miRNA), a group of small non-coding RNAs, are involved in HER2 signaling and trastuzumab treatment. This review summarizes all the miRNAs that target HER2 and describes their activity on biological processes. Moreover, miRNAs that regulate trastuzumab resistance and relevant molecular mechanisms are highlighted. MiRNA signatures associated with HER2, miRNAs that mediate trastuzumab activity, and potential miRNA biomarkers of trastuzumab sensitivity are also discussed.

Host immunity and tumor microenvironment significantly influence follicular lymphoma (FL) outcomes. Lymphopenia has been identified as a negative prognostic factor for FL. However, there is limited data regarding prognostic value of peripheral blood T lymphocyte subsets, especially absolute CD4 + T cell counts (ACD4C) in FL. We studied 127 consecutive FL patients to investigate whether peripheral blood ACD4C or absolute monocytes (AMC) at diagnosis had an impact on FL prognosis. In our cohort, both low ACD4C and high AMC were the parameters associated with inferior progression-free survival (PFS) (P = 0.021 and P = 0.013, respectively) and inferior overall survival (OS) (P = 0.020 and P = 0.005, respectively) by univariate analysis. Multivariate analysis revealed that only low ACD4C was statistically significant in worse PFS (hazard ratio, 2.811; 95 % confidence interval, 1.137-6.950; P = 0.025) and shorter OS (hazard ratio, 3.393; 95 % confidence interval, 1.037-11.105; P = 0.043) independent of FLIPI-2. Evaluation of blood ACD4C could be a useful indicator of outcome in previously untreated FL patients.

Background: Carbohydrate antigen 125 (CA-125) is one of the most common used tumor biomarkers in clinical practice. Previous studies showed an association of increased CA-125 levels with advanced characteristics and inferior outcome in non-Hodgkin lymphoma., Objective: To identify the clinical significance of CA-125 in diffuse large B-cell lymphoma (DLBCL)., Methods: We retrospectively analyzed 181 patients with DLBCL with measured serum CA-125 concentration at diagnosis and follow-ups during the courses. Clinical significance of CA-125 was evaluated by assessing the association between CA-125 levels and clinical characteristics., Results: CA-125 levels on admission were positively correlated with serum lactate dehydrogenase, β2-microglobulin (β2-MG), serum ferritin (SF) and cavity effusion, while negatively correlated with serum albumen (ALB). During the courses, CA-125 levels were positively correlated with β 2-MG, SF and effusion, and negatively correlated with ALB. A better correlation between effusion and CA-125 levels was observed. Using a cut-off value > 50.39 U/ml gave a sensitivity of 73.8% and a specificity of 92.1% for the indication of effusion at diagnosis, while during the courses the sensitivity was much lower. On the prognostic role of CA-125, we found prognostic relevance on progression-free survival (PFS) but not on overall survival (OS)., Conclusions: Our study revealed limited usefulness of CA-125 concentration at diagnosis and follow-ups in DLBCL.

This study aimed to detect the interactions of several single nucleotide polymorphisms (SNPs) and alcohol consumption on blood pressure levels. Genotypes of 10 SNPs in the ATP-binding cassette transporter A1 (ABCA-1), acyl-CoA:cholesterol acyltransferase-1 (ACAT-1), low density lipoprotein receptor (LDLR), hepatic lipase gene (LIPC), endothelial lipase gene (LIPG), methylenetetrahydrofolate reductase (MTHFR), the E3 ubiquitin ligase myosin regulatory light chain-interacting protein (MYLIP), proprotein convertase subtilisin-like kexin type 9 (PCSK9), peroxisome proliferator-activated receptor delta (PPARD), and Scavenger receptor class B type 1 (SCARB1) genes were determined in 616 nondrinkers and 608 drinkers. The genotypic frequencies of LDLR rs5925, LIPC rs2070895, MTHFR rs1801133, and MYLIP rs3757354 SNPs were significantly different between nondrinkers and drinkers. The levels of systolic blood pressure (ABCA-1 rs2066715 and rs2070895), diastolic blood pressure (rs2070895), and pulse pressure (PP) (rs2066715, ACAT-1 rs1044925, and rs1801133) in nondrinkers, and systolic blood pressure (rs1044925 and SCARB1 rs5888), diastolic blood pressure (rs1044925 and LIPG rs2000813), and PP (PCSK9 rs505151 and rs5888) in drinkers were different among the genotypes (P < 0.005-0.001). The interactions of several SNPs and alcohol consumption on systolic blood pressure (rs2066715, rs1044925, rs5925, rs2070895, rs1801133, rs3757354, PPARD rs2016520, and rs5888), diastolic blood pressure (rs2066715, rs1044925, rs5925, rs2000813, rs3757354, and rs2016520), and PP (rs1044925, rs2070895, rs1801133, rs3757354, rs505151, and rs5888) were observed (P < 0.005-0.001). The differences in blood pressure levels between the nondrinkers and drinkers might be partially attributed to the interactions of these SNPs and alcohol consumption., (© 2015 International Union of Biochemistry and Molecular Biology.)

MicroRNAs (miRNAs) are small noncoding RNA molecules which regulate the target gene expression posttranscriptionally. Increasing studies have shown that microRNAs play important roles in multiple biological pathways. For instance, aberrant expression of microRNA-224 (miR-224) plays a vital role in tumor biology in various types of human cancer. Here, we aim to summarize the molecular mechanisms that lead to the overexpression of miR-224 in cancers, analyze the effect of miR-224 on tumor biology, and reveal the clinical significance of miR-224. MiR-224 regulates its targets by modulating messenger RNA (mRNA) stability and/or protein translation, and it would provide new insight into molecular targeting cancer treatment.

Diabetic patients have a signifiantly higher risk of developing all forms of dementia. Pentamethylquercetin (PMQ) has been proven to have potential as an anti-diabetic agent. Nevertheless, whether PMQ can improve diabetes-induced cognitive dysfunction has not been investigated. To address this, we evaluated the effectiveness and underlying mechanisms of PMQ for ameliorating diabetes-related cognitive dysfunction in vivo and in vitro. Our results showed that Goto-Kakizaki (GK) rats displayed impairment in their learning abilities and memory capabilities. Furthermore, GK rats reflected cognitive dysfunction in proportion to the intensity of insulin resistance index. In addition, dendritic spine density and the % cell viability significantly decreased in hippocampus neurons. High glucose conditions induced hippocampal neurons damage, inflicted dendritic spine dysontogenesis, and reduced Akt/cAMP response element-binding protein activation. Treatment with PMQ in GK rats significantly ameliorated cognitive deficits and neuronal damage and increased dendritic spine density, at least in part, by improving insulin resistance and metabolic disorders. Furthermore, PMQ significantly activated the Akt/cAMP response element-binding protein pathway and increased the expression of memory-related proteins in the downstream part of the Akt/cAMP response element-binding protein pathway, such as synaptophysin and glutamate receptor 1. In addition, PMQ inhibited high glucose-induced cellular toxicity. LY294002 appeared to partly inhibit PMQ-mediated protective effects in hippocampal neurons. The results suggest that insulin resistance could predominantly reduce Akt/cAMP response element-binding protein activation in the brain, which is associated with a higher risk of cognitive dysfunction. PMQ could provide a new potential option for the prevention of cognitive dysfunction in diabetes.

Gloves with anti-vibration features are increasingly used to reduce impact vibrations or shocks transmitted to the hands of power tool operators. Selection and evaluation of the glove materials are important steps in the designs of such gloves. In the current study, we proposed an approach to objectively evaluate the effectiveness of the glove materials using a rat-tail impact model. As a critical part of a systematic investigation, we examined the vibration reduction characteristics of typical resilient glove materials (air bladders and viscoelastic gels) and the impact vibrations transmitted to the rat tail. A special test platform that mimics impact tool vibrations was constructed and used in the experiment. A scanning laser vibrometer was used to measure the vibration at points across the platform surface under several different test conditions. The peak acceleration was found to be greatly attenuated by the glove materials, especially by using strips from a gel-filled glove. The rat tail was found to effectively absorb the high-frequency vibration. However, the glove materials and the rat tail did not reduce the frequency-weighted acceleration. The implications of the experimental results are discussed.

Biomechanical models of the hand and fingers are useful tools for hand surgeons to improve surgical procedures and for biomedical researchers to explore the mechanical loading in the musculoskeletal system that cannot be easily measured in vivo. The purpose of the present study was to develop a realistic index finger model for solving practical problems. The model includes the meshes of four bony sections (distal, middle, proximal and metacarpal bones) obtained via micro-CT scans. The tendon attachment sites are adopted from the normative finger model. A total of seven tendon/muscles are included in the model. The predicted tendon excursions and moment arms were compared with published experimental data. One of the advantages of the current approach over previous studies is that the current model has been developed on a platform of a commercial software package, such that researchers can apply it as a universal tool for practical problems.

Gasification of polyvinyl alcohol (PVA)-contaminated wastewater in supercritical water (SCW) was investigated in a continuous flow reactor at 723-873 K, 20-36 MPa and residence time of 20-60 s. The gas and liquid products were analyzed by GC/TCD, and TOC analyzer. The main gas products were H2, CH4, CO and CO2. Pressure change had no significant influence on gasification efficiency. Higher temperature and longer residence time enhanced gasification efficiency, and lower temperature favored the production of H2. The effects of KOH catalyst on gas product composition were studied, and gasification efficiency were analyzed. The TOC removal efficiency (R(TOC), carbon gasification ratio (R(CG)) and hydrogen gasification ratio (R(HG)) were up to 96.00%, 95.92% and 126.40% at 873 K and 60 s, respectively, which suggests PVA can be completely gasified in SCW. The results indicate supercritical water gasification for hydrogen generation is a promising process for the treatment of PVA wastewater.

Knowledge of viscoelastic properties of soft tissues is essential for the finite element modelling of the stress/strain distributions in finger-pad during vibratory loading, which is important in exploring the mechanism of hand-arm vibration syndrome. In conventional procedures, skin and subcutaneous tissue have to be separated for testing the viscoelastic properties. In this study, a novel method has been proposed to simultaneously determine the viscoelastic properties of skin and subcutaneous tissue in uniaxial stress relaxation tests. A mathematical approach has been derived to obtain the creep and relaxation characteristics of skin and subcutaneous tissue using uniaxial stress relaxation data of skin/subcutaneous composite specimens. The micro-structures of collagen fiber networks in the soft tissue, which underline the tissue mechanical characteristics, will be intact in the proposed method. Therefore, the viscoelastic properties of soft tissues obtained using the proposed method would be more physiologically relevant than those obtained using the conventional method. The proposed approach has been utilized to measure the viscoelastic properties of soft tissues of pig. The relaxation curves of pig skin and subcutaneous tissue obtained in the current study agree well with those in literature. Using the proposed approach, reliable material properties of soft tissues can be obtained in a cost- and time-efficient manner, which simultaneously improves the physiological relevance.

Many work related injuries stem from the exertion of skeletal muscle forces over an extended period of time. Musculoskeletal injury can be caused by muscle's inability to maintain force during occupational exposure. The goal of the present study is to test how various rest times (duty cycles) between long isometric contractions will affect decrements in force, and develop a model that characterizes force decrements due to skeletal muscle fatigue. All tests were performed in vivo on the tibialis anterior muscle of anesthetized Sprague-Dawley rats. Animals were randomly assigned to either a 10 second (N=8), 1 minute (N=8), or 5 minute (N=8) duty cycle group. All animals were then subjected to 7 isometric contractions (duration of 2.8 seconds). A model was constructed to characterize forces changes over the duration of a contraction and over multiple contractions. The model consisted of a power law and an exponential component; these two components were combined by using an exponential weighting function. Overall, the combination of a power law and exponential model with a weighting function satisfactorily characterized the changes in isometric force for the 10 second duty cycle, but a simpler exponential model could be used where longer duty cycles are performed.

Tendon injuries may result in variations of its mechanical properties. The published data of the tendon stiffness of small animals, such as mouse and rat, are exclusively obtained by measuring grip-to-grip (g-t-g) displacement. Local strain concentration and relative sliding of the specimens in the clamps might significantly affect the measured tendon deformation. In the present study, the mechanical properties of the rat tibialis anterior tendon measured using the proposed tendon mark method were compared to those evaluated using the g-t-g displacement method. Five male Sprague Dawley rats ( approximately 418 g) were used in this study. For the proposed method, reference marks were made on the tendons using permanent ink. A microscope video system was customized to observe and record the tendon deformation. Pattern recognition software was developed to obtain the displacement time-histories of the reference marks. The distance between the grips was approximately 7 mm; and the distance between the reference marks used for the data processing was approximately 5 mm. The cross-section areas of the specimens were measured using a custom-made slot gauge and by applying a constant compressive stress (0.15 MPa). The tendons were clamped between two custom-made metal grips and stretched on a testing machine at a constant speed (1 mm/s) up to failure. Throughout the tests, the tendon specimens were submerged in a PBS bath at 22 degrees C. The deformation of the specimens was evaluated using the g-t-g displacement method and the proposed method. The stress/strain curves obtained by using the g-t-g displacement can be characterized by an initial toe zone, a quasi-linear zone, and a final failure stage. The stress/strain curves determined using the proposed method are quite different from those obtained using the g-t-g displacement: it has a smaller toe zone and a stress-hardening transition, over which the tendon stiffness increases dramatically with the increasing strain. The tendon stiffness measured by using the g-t-g displacement method may underestimate the actual mechanical properties of tendon by approximately 43%.

In physiological loading conditions, the soft tissues in the hands and fingers are predominantly in compression. The goal of the present study was to characterize the nonlinear and time-dependent behavior of skin in compression. The pigskin samples used in the study were collected from five different animals. The compression tests were performed in confined and unconfined loading configurations and at four different loading speeds (0.5, 1.0, 40, and 400 microm/s). A multi-axial material model was proposed to simulate the nonlinear and viscoelastic behavior of the skin in compression. The good agreement between the model predictions and experimental data suggests that the mechanical behavior of the skin in compression can be well characterized using the Ogden strain energy potential combined with a time-integration using a Prony series. Our results show that the stress/strain curve of the skin is much stiffer in confined compression compared to that in unconfined compression, indicating that the compressibility of the skin is small.