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Mechanical loading

Zishuo Cheng, Pei W Thomas, Lincheng Ju, Alexander Bergstrom, Kelly Mason, Delaney Clayton, Callie Miller, Christopher R Bethel, Jamie VanPelt, David L Tierney, Richard C Page, Robert A Bonomo, Walter Fast, Michael W Crowder
Infections by carbapenem-resistant Enterobacteriaceae (CRE) are difficult to manage owing to broad antibiotic resistance profiles and because of the inability of clinically-used β-lactamase inhibitors to counter the activity of metallo-β-lactamases often harbored by these pathogens. Of particular importance is New Delhi metallo-β-lactamase (NDM), which requires a dinuclear zinc ion cluster for catalytic activity. Here, we compare the structures and functions of clinical NDM variants 1-17. The impact of NDM variants on structure is probed by comparing comparing melting temperature and refolding efficiency and also by spectroscopy (UV-Vis, 1 H-NMR, and EPR) of di-cobalt metalloforms...
June 16, 2018: Journal of Biological Chemistry
Min Gong, Cheng Chi, Jingjing Ye, Meihong Liao, Wenqi Xie, Chengai Wu, Rui Shi, Liqun Zhang
Due to the significant role of the periosteum in bone regeneration, we hypothesised that using a specially engineered artificial periosteum could lead to an enhancement in osteogenesis in bone grafts. Herein, we describe our work aimed at fabricating an electrospun fibrous membrane as an artificial periosteum that exhibits flexibility, permeability and osteoinduction. This membrane was designed to cover the complex surface of bone grafts to facilitate and accelerate bone regeneration. The traditional Chinese medicine icariin (ICA) was subsequently introduced into poly (ε-caprolactone) (PCL) /gelatin nanofibers to fabricate an artificial periosteum for the first time...
June 14, 2018: Colloids and Surfaces. B, Biointerfaces
Tyler J D'Ovidio, Rebecca M Roberts, Dixa Gautam, Zefram D Marks, Manju Saraswathy, Jeffrey W Stansbury, Devatha P Nair
The enhanced in situ photopolymerization kinetics of methyl methacrylate (MMA) to poly(methyl methacrylate) (PMMA) through the incorporation of both inert and reactive nanogel (NG) fillers under ambient conditions has been demonstrated. In addition to the polymerization kinetics, the physical and chemical properties of the prepolymeric NG were also utilized to tune the thermoplasticity and mechanical properties of the PMMA polymer network. The protocol followed in this study imparts superior MMA photopolymerization kinetics (≥ 60% double-bond conversion within 15 min for > 35 wt% nanogel loadings and ≥ 95% double-bond conversion in < 60 min for all NG concentrations) when compared with traditional polymerization mechanisms...
June 2, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Gang Mu, Fuhai Duan, Guochen Zhang, Xiuchen Li, Xiaofei Ding, Lei Zhang
In order to provide reference for the development of relevant dredging and processing machinery of the manila clam (Ruditapes philippinarum), the clam shell´s microstructure, phase composition, microhardness, nanoindentation hardness and elastic modulus were investigated, the quasi static compression and orthogonal compression tests of live clams were carried out as well. The shell consists of the outer, middle, and inner layer, which correspond with the composite prismatic structure, crossed-lamellar structure, and homogeneous structure, respectively...
June 14, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Jungsun Hong, Franz Kevin Geronimo, Hyeseon Choi, Lee-Hyung Kim
Low-impact development (LID) techniques are being applied to reduce non-point source (NPS) pollution which are generated from various land uses. Cost-effective LID design requires consideration of influent runoff properties as well as physical and ecological pollutant-removing mechanisms. However, current LID technology design has failed to reflect the different properties of influent water from various land uses, and the biological design factors in LID facilities causing low efficiency and difficulties in maintenance...
June 9, 2018: Chemosphere
Haohui Zhan, Fengsen Ma, Yingcong Huang, Jie Zhang, Xiayun Jiang, Yongchang Qian
We report a type of dissolving microneedles (DMNs) which was made of composite matrix materials of hydroxypropyl methyl cellulose (HPMC) and poly(methylvinylether‑co‑maleic anhydride) (PMVE/MA copolymer, Gantrez S-97), and was successfully loaded with lidocaine hydrochloride. The weight of lidocaine hydrochloride loaded in the microneedles tip was 70% of the weight of the whole tip. The content was 3.43 ± 0.12 mg in weight, which was determined by high performance liquid chromatography (HPLC). The results for mechanical test showed that these microneedles were able to penetrate into the skin of the experimental animals, that was proved using organic staining, texture analyzer and histological examination...
June 14, 2018: European Journal of Pharmaceutical Sciences
Dennis Kolosov, Maria Tauqir, Sabitha Rajaruban, Peter M Piermarini, Andrew Donini, Michael J O'Donnell
Classical studies have described in detail the complex and regionalized morphology of the Malpighian tubule (MT) in larval Lepidoptera. Recent studies revealed unusual aspects of ion transport in the Malpighian tubules of the larva of the cabbage looper, Trichoplusia ni. These included: cation reabsorption via secondary cells (SC); coupling of SCs to neighbouring PCs via gap junctions to enable reabsorption; and a reversal from cation secretion to reabsorption by the principal cells in the distal ileac plexus region of the in situ tubule in response to dietary ion loading...
June 14, 2018: Journal of Insect Physiology
Matej Par, Nika Spanovic, Ruza Bjelovucic, Hrvoje Skenderovic, Ozren Gamulin, Zrinka Tarle
OBJECTIVES: The aim of this work was to investigate the curing potential of an experimental resin composite series with the systematically varying amount of bioactive glass 45S5 by evaluating the degree of conversion, light transmittance and depth of cure. METHODS: Resin composites based on a Bis-GMA/TEGDMA resin with a total filler load of 70 wt% and a variable amount of bioactive glass (0-40 wt%) were prepared. The photoinitiator system was camphorquinone and ethyl-4-(dimethylamino) benzoate...
June 14, 2018: Journal of Dentistry
Paula Pluta, Pietro Roversi, Ganeko Bernardo-Seisdedos, Adriana L Rojas, Jonathan B Cooper, Shuang Gu, Richard W Pickersgill, Oscar Millet
Human porphobilinogen deaminase (PBGD), the third enzyme in the heme pathway, catalyzes four times a single reaction to convert porphobilinogen into hydroxymethylbilane. Remarkably, PBGD employs a single active site during the process, with a distinct yet chemically equivalent bond formed each time. The four intermediate complexes of the enzyme have been biochemically validated and they can be isolated but they have never been structurally characterized other than the apo- and holo-enzyme bound to the cofactor...
June 14, 2018: Biochimica et Biophysica Acta
Sorin Siegler, Tobias Konow, Claudio Belvedere, Andrea Ensini, Rewati Kulkarni, Alberto Leardini
Joint surface interaction and ligament constraints determine the kinematic characteristics of the ankle and subtalar joints. Joint surface interaction is characterized by joint contact mechanics and by relative joint surface position potentially characterized by distance mapping. While ankle contact mechanics was investigated, limited information is available on joint distance mapping and its changes during motion. The purpose of this study was to use image-based distance mapping to quantify this interaction at the ankle and subtalar joints during tri-planar rotations of the ankle complex...
June 7, 2018: Journal of Biomechanics
Nicholas Martin, George Youssef
Hydrophilic polymers, or hydrogels, are used for a wide variety of biomedical applications, due to their inherent ability to withhold a high-water content. In recent years, a large effort has been focused on tailoring the mechanical properties of these hydrogels to become more appropriate materials for use as anatomical and physiological structural supports. A few of these such methods include using diverse types of polymers, both natural and synthetic, varying the type of molecular cross-linking, as well as combining these efforts to form interpenetrating polymer network hydrogels...
June 7, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Yusuf Olgar, Sinan Degirmenci, Aysegul Durak, Deniz Billur, Belgin Can, Gizem Kayki Mutlu, Ebru Arioglu Inan, Belma Turan
Aging in humans represents declining in cardio-protective systems, however its mechanisms are not known yet. We aimed to analyse how aging affects key mechanisms responsible for contractile dysfunction via comparing the improperly synchrony between electrical and mechanical activities in male aged-rats (24-month old) comparison to those of adult-rats (6-month old). We determined significantly increased systemic oxidative stress with decreased antioxidant capacity, clear insulin resistance and hypertrophy in aged-rats with normal fasting blood glucose...
June 13, 2018: Experimental Gerontology
Yuanfeng Pan, Jingchun Wang, PingxiongCai, Huining Xiao
In this work, the stepwise synthesis of interpenetrating polymer network (IPN) strategy was developed in an attempt to fabricate novel hydrogels consisting of sugarcane bagasse cellulose (SBC), carboxymethylcellulose (CMC) and poly (N-isopropylacrylamide) (PNIPAm) as a dual-responsive drug carrier. The pretreated and dissolved SBC was pre-crosslinked using epichlorohydrin in the presence of CMC, followed by in-situ free-radical polymerization of NIPAm in the presence of N,N'-Methylene-bis(acrylamide) as a crosslinking agent...
June 13, 2018: International Journal of Biological Macromolecules
Mayson H Alkhatib, Waad A Al-Otaibi, Abdulwahab Noor Wali
Combining the essential oils (ESSOs) with the chemotherapeutic agent, mitomycin C (MMC), in nanoparticle can be beneficial in cancer therapy. The aim of the current study was to in vitro evaluate the antineoplastic effect of MMC, formulated in two different nanoemulsions (NE) based on two ESSOs, chamomile (Ch) and garlic (Gar), on HeLa cervical cancer cells. The z-average diameter of Ch-NE has slightly increased from 83.39 ± 12.85 nm to 91.18 ± 5.79 nm when mixed with MMC (Ch-MMC) whereas the z-average diameter of Gar-NE has markedly increased from 50...
June 13, 2018: Chemico-biological Interactions
Lei Yu, Vladislav A Petyuk, Chris Gaiteri, Sara Mostafavi, Tracy Young-Pearse, Raj C Shah, Aron S Buchman, Julie A Schneider, Paul D Piehowski, Ryan L Sontag, Thomas L Fillmore, Tujin Shi, Richard D Smith, Philip L De Jager, David A Bennett
OBJECTIVE: Previous gene expression analysis identified a network of co-expressed genes that is associated with β-amyloid neuropathology and cognitive decline in older adults. The current work targeted influential genes in this network with quantitative proteomics to identify potential novel therapeutic targets. METHODS: Data came from 834 community-based older persons who were followed annually, died and underwent brain autopsy. Uniform structured postmortem evaluations assessed the burden of β-amyloid and other common age-related neuropathologies...
June 16, 2018: Annals of Neurology
Tingwang Guo, Peng Ren, Xiaofei Li, Tiantian Luo, Yuhua Gong, Shilei Hao, Bochu Wang
Mass effect induced by growing hematoma is one of the mechanisms by which intracerebral hemorrhage (ICH) may result in brain injuries. Our goal was to investigate the damage mechanism of hydrostatic pressure associated with mass effect and the cooperative effect of hydrostatic pressure plus hemoglobin on neural injuries. Loading hydrostatic pressure on neurons and injecting agarose gel in the right striatum of rats was performed to establish the in vitro and vivo ICH models, respectively. The elevated hydrostatic pressure associated with ICH suppressed neurons and neural tissues viability, and disturbed the axons and dendrites in vitro and vivo...
June 15, 2018: Scientific Reports
S Scudino, J J Bian, H Shakur Shahabi, D Şopu, J Sort, J Eckert, G Liu
A prerequisite to utilize the full potential of structural heterogeneities for improving the room-temperature plastic deformation of bulk metallic glasses (BMGs) is to understand their interaction with the mechanism of shear band formation and propagation. This task requires the ability to artificially create heterogeneous microstructures with controlled morphology and orientation. Here, we analyze the effect of the designed heterogeneities generated by imprinting on the tensile mechanical behavior of the Zr52...
June 15, 2018: Scientific Reports
Soojung Lee, Trine V Axelsen, Nicolai Jessen, Stine F Pedersen, Pernille Vahl, Ebbe Boedtkjer
Metabolic acid production challenges cellular pH homeostasis in solid cancer tissue, and mechanisms of net acid extrusion represent promising new targets for breast cancer therapy. Here, we used genetically engineered mice to investigate the contribution of the Na+ ,HCO3 - -cotransporter NBCn1 (Slc4a7) to intracellular acid-base regulation in ErbB2-induced breast cancer tissue and the consequences of NBCn1 knockout for breast tumor development and growth. We demonstrate an approximately 2-fold increase of NBCn1 protein abundance in ErbB2-induced breast cancer tissue compared to normal breast tissue despite a 4-fold decrease in the NBCn1 mRNA level...
June 15, 2018: Oncogene
Annia Schreiber, Michele Bertoni, Ewan C Goligher
Both limb muscle weakness and respiratory muscle weakness are exceedingly common in critically ill patients. Respiratory muscle weakness prolongs ventilator dependence, predisposing to nosocomial complications and death. Limb muscle weakness persists for months after discharge from intensive care and results in poor long-term functional status and quality of life. Major mechanisms of muscle injury include critical illness polymyoneuropathy, sepsis, pharmacologic exposures, metabolic derangements, and excessive muscle loading and unloading...
July 2018: Critical Care Clinics
Navish Kataria, V K Garg
This study focused on the synthesis and characterization of novel magnetic iron oxide nanoparticles loaded sawdust carbon (Fe3 O4 /SC) and EDTA modified Fe3 O4 /SC (EDTA@Fe3 O4 /SC) nanocomposites (ncs) by low cost biogenic green synthesis approach and their application for Cd (II) removal from aqueous medium in batch mode. In isotherm studies, Langmuir and Freundlich models are best fitted to Cd (II) removal data. Langmuir maximum adsorption capacity of EDTA@Fe3 O4 /SC ncs was found to be 63.3, 22.4 and 25 mg/g that is greater than maximum adsorption capacity of Fe3 O4 /SC ncs that is 51, 18...
June 4, 2018: Chemosphere
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