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Closed kinetic chain

D Aurora Perini, Antonio Alcaraz, María Queralt-Martín
The outer membrane of Gram-negative bacteria contains β-barrel proteins that form high-conducting ion channels providing a path for hydrophilic molecules, including antibiotics. Traditionally, these proteins have been considered to exist only in an open state so that regulation of outer membrane permeability was accomplished via protein expression. However, electrophysiological recordings show that β-barrel channels respond to transmembrane voltages by characteristically switching from a high-conducting, open state, to a so-called 'closed' state, with reduced permeability and possibly exclusion of large metabolites...
February 5, 2019: International Journal of Molecular Sciences
Matthew Buckthorpe, Giovanni La Rosa, Francesco Della Villa
One of the main priorities of rehabilitation after anterior cruciate ligament reconstruction (ACLR) surgery is the restoration of knee extensor muscle strength. Residual deficits in knee extensor muscle size and strength after injury are linked to poor biomechanics, reduced knee function, increased knee osteoarthritis risk, as well as heightened risk of re-injury upon return to sport. Most studies indicate that knee extensor muscle strength is typically not resolved prior to return to sport. This clinical commentary discusses strategies to optimize and accelerate the recovery of knee extensor strength post-surgery, with the purpose to support the clinician with evidence-based strategies to implement into clinical practice...
February 2019: International Journal of Sports Physical Therapy
Maryam Bakhtiari, Lars Konermann
Experiments and molecular dynamics (MD) simulations in the literature indicate that gaseous proteins generated by electrospray ionization (ESI) can retain native-like structures. However, the exact properties of these ions remain to be explored. Focusing on ubiquitin and lysozyme, we examined several pertinent questions. (1) We applied solvent MD runs to test whether the X-ray structures of both proteins are affected by crystal packing. Main and side chain orientations were retained in solution, providing a justification for the hitherto unscrutinized approach of relying on crystal data for "solution" vs...
February 6, 2019: Journal of Physical Chemistry. B
Nicholus Bhattacharjee, Sébastien Triboulet, Vincent Dubée, Matthieu Fonvielle, Zainab Edoo, Jean-Emmanuel Hugonnet, Mélanie Ethève-Quelquejeu, Jean-Pierre Simorre, Martin J Field, Michel Arthur, Catherine M Bougault
The Ldtfm L,D-transpeptidase mediates resistance to most β-lactam antibiotics in Enterococcus faecium by replacing classical peptidoglycan polymerases. The catalytic Cys of Ldtfm is rapidly acylated by β-lactams belonging to the carbapenem class but not by penams and cephems. We previously reported quantum calculations and kinetic analyses for Ldtfm and showed that the inactivation profile is not determined by differences in drug binding ( K D values in the 50-80 mM range). Here, we analyze the reaction of a Cys sulfhydryl with various β-lactams in the absence of the enzyme environment in order to compare the intrinsic reactivity of drugs belonging to the penam, cephem, and carbapenem classes...
February 4, 2019: Antimicrobial Agents and Chemotherapy
Dawid Bączkowicz, Krzysztof Kręcisz, Zbigniew Borysiuk
BACKGROUND: Knee movements performed in open (OKC) and closed (CKC) kinetic chains generate various patterns of muscle activities and especially distinct contact stresses in the patellofemoral joint (PFJ). In contrast to these features, the arthrokinematic motion quality (AMQ) of the PFJ has not been compared between mentioned conditions. In this study we performed vibroarthrographic analysis of AMQ in movements performed in OKC and CKC, in healthy subjects and individuals with chondromalacia patellae, to assess which of the test conditions is more efficient in differentiation between healthy and deteriorated joints...
January 31, 2019: BMC Musculoskeletal Disorders
Mahnaz Daman, Farideh Shiravani, Ladan Hemmati, Shohreh Taghizadeh
OBJECTIVE: Proprioception, the perception of limb movements and spatial orientation derived from body stimuli, plays a critical role in maintaining joint stability. This study aimed to investigate the effect of combined exercise therapy (closed kinetic chain exercises and proprioception exercises) on knee proprioception, pain intensity and quality of life in patients with hypermobility syndrome. DESIGN: Single-blind randomized clinical trial. SETTING: Shiraz School of Rehabilitation Sciences...
January 2019: Journal of Bodywork and Movement Therapies
Ke Luo, Kyu-Hwan Park, Da-Hee Lee, Chae-Eun Hong, Young-Woon Song, Sang-Ho Yoo, Young-Rok Kim
Starch microparticles (SMPs) of well-defined size and morphology were synthesized through pullulanase-mediated debranching of waxy maize starch followed by spontaneous re-assembly of the resulting short-chain glucan molecules in aqueous solution. Enzymatic debranching of amylopectins from native starch generated two major fractions corresponding to a smaller glucan and partially digested larger amylopectin molecules. The ratio of short-chain glucan (SCG) over partially digested amylopectin (PDAp) turned out to be the deterministic factors for the size and crystallinity of SMPs, of which the ratio could be controlled by the concentration of debranching enzyme...
January 8, 2019: Colloids and Surfaces. B, Biointerfaces
Mallory R Smith, David D Shock, William A Beard, Marc M Greenberg, Bret D Freudenthal, Samuel H Wilson
4,6-Diamino-5-formamidopyrimidine (Fapy•dG) is an abundant form of oxidative DNA damage that is mutagenic and contributes to the pathogenesis of human disease. When Fapy•dG is in its nucleotide triphosphate form, Fapy•dGTP, it is inefficiently cleansed from the nucleotide pool by the responsible enzyme in Escherichia coli MutT and its mammalian homolog MTH1. Therefore, under oxidative stress conditions, Fapy•dGTP could become a pro-mutagenic substrate for insertion into the genome by DNA polymerases...
January 16, 2019: Nucleic Acids Research
Wolfgang Fitz, Pinak Shukla, Ling Li, Richard D Scott
Background: Techniques that allow early muscle activation, such as closed kinetic chain (CKC) and open kinetic chain (OKC) exercises, may play a beneficial role in the early rehabilitation of the reconstructed knee. However, current rehabilitation regimens have not been shown to reverse post-operative quadriceps activation failure and weakness. To investigate whether patients who use a continuous active motion (CAM) device that follows closed kinetic chain principles have better early post-operative functional improvements than patients who use a continuous passive motion (CPM) device that follows the principles of open kinetic chain principles...
November 2018: Archives of Bone and Joint Surgery
Sophie Heywood, Jodie McClelland, Paula Geigle, Ann Rahmann, Elizabeth Villalta, Benjamin Mentiplay, Ross Clark
BACKGROUND: Closed kinetic chain and plyometric exercises are commonly used in aquatic rehabilitation because they are believed to reduce joint loading whilst replicating functional tasks. However, the forces and relationship to land-based functional movement is unknown. This study aims to compare vertical ground reaction force during squats, calf raises and jumping in older adults with and without knee osteoarthritis on land and in water. METHODS: Forty one participants (Healthy n = 21; Knee osteoarthritis n = 20; Age 68...
January 2, 2019: Knee
Mariia N Ivanova, Andrey N Enyashin, Ekaterina D Grayfer, Vladimir E Fedorov
The extensive family of transition metal chalcogenides has been comprehensively investigated owing to their diverse useful properties. However, even among them, there are ones that have received comparatively less attention; in particular, these are molybdenum and niobium sulfides and selenides with the composition of M : Q = 2 : 3 (M = Mo, Nb; Q = S, Se). Mo or Nb chalcogenides with this stoichiometry may adopt one of two structures: (i) sesquichalcogenides M2Q3, where important structural elements are infinite metal chains, or (ii) self-intercalated compounds M1...
January 4, 2019: Physical Chemistry Chemical Physics: PCCP
Ekaterina Yu Bezsudnova, Konstantin M Boyko, Alena Yu Nikolaeva, Yulia S Zeifman, Tatiana V Rakitina, Dmitry A Suplatov, Vladimir O Popov
The high catalytic efficiency of enzymes under reaction conditions is one of the main goals in biocatalysis. Despite the dramatic progress in the development of more efficient biocatalysts by protein design, the search for natural enzymes with useful properties remains a promising strategy. The PLP-dependent transaminases represent a group of industrially important enzymes due to their ability to stereoselectively transfer amino groups between diverse substrates; however, the complex mechanism of substrate recognition and conversion makes the design of transaminases a challenging task...
December 29, 2018: Biochimie
Uladzimir Barayeu, Mike Lange, Lucía Méndez, Jürgen Arnhold, Oleg I Shadyro, Maria Fedorova, Jörg Flemmig
Cytochrome c (cyt c) is a small hemoprotein involved in electron shuttling in the mitochondrial respiratory chain and is now also recognized as an important mediator of apoptotic cell death. Its role in inducing programmed cell death is closely associated with the formation of a complex with the mitochondrion-specific phospholipid cardiolipin (CL), leading to a gain of peroxidase activity. Yet the molecular mechanisms behind this gain and eventual cyt c auto-inactivation via its release from mitochondria membranes remains largely unknown...
December 12, 2018: Journal of Biological Chemistry
Sophia L Gonzalez, Aimee M Diaz, Hillary A Plummer, Lori A Michener
CONTEXT: Rowers are at risk for overuse injuries, including low back pain (LBP). Defining the utility of screening tests for identifying those at risk for LBP can aid in the development of guidelines for injury prevention. OBJECTIVE: To determine if the Functional Movement Screen (FMS) and impairments can identify rowers at risk for developing LBP. DESIGN: Prospective cohort study. SETTING: Athletic training room. PATIENTS OR OTHER PARTICIPANTS: A total of 31 National Collegiate Athletic Association Division I, female, open-weight rowers (age = 19...
December 2018: Journal of Athletic Training
Robert Prill, Sven Michel, Robert Schulz, Hans-Joachim Appell Coriolano
The purpose of this study was to investigate if there are still deficits in muscle mass or strength capabilities in elite judo athletes with a history of anterior cruciate ligament reconstruction (ACLR) after their return to the sport. Therefore, bioimpedance analysis, 3D-laser thigh circumference measurement and isokinetic dynamometry in a closed kinetic chain were used. The side-to-side differences were investigated in a group of judo athletes 5 years after ACLR (n=17) and compared with a group of healthy judo athletes (n=27)...
January 2019: International Journal of Sports Medicine
Ali Çağdaş Yörükoğlu, Raziye Şavkın, Nihal Büker, Khaled Yahya Abdullah Alsayani
BACKGROUND: Strong core stabilization not only minimizes the load on the vertebral column, but also improves strength and endurance of peripheral joints, and enables the energy transfer to distal segments. Despite the current interest surrounding core stability, none of the studies investigated the effect of core stability on the formation of rotator cuff tear or healing after repair. OBJECTIVE: To determine the relationship between core stability and upper extremity functional performance in patients who underwent rotator cuff repair surgery and to compare those with healthy subjects of similar age...
November 16, 2018: Journal of Back and Musculoskeletal Rehabilitation
Archie C Reyes, David C Plache, Astrid P Koudelka, Tina L Amyes, John A Gerlt, John P Richard
We report the results of a study of the catalytic role of a network of four interacting amino acid side chains at yeast orotidine 5'-monophosphate decarboxylase (ScOMPDC), by the stepwise replacement of all four side chains. The H-bond, which links the -CH2 OH side chain of S154 from the pyrimidine umbrella loop of ScOMPDC to the amide side chain of Q215 in the phosphodianion gripper loop, creates a protein cage for the substrate OMP. The role of this interaction in optimizing transition state stabilization from the dianion gripper side chains Q215, Y217 and R235 was probed by determining the kinetic parameter kcat /Km for 16 enzyme variants, which include all combinations of single, double, triple and quadruple mutations of S154A Q215A, Y217F and R235A...
November 26, 2018: Journal of the American Chemical Society
Jordy Bouwman, Andras Bodi, Patrick Hemberger
A solid understanding of and a reliable model for the formation pathways of polycyclic aromatic (nitrogen containing) hydrocarbons (PA(N)Hs) is needed to account for their abundance in the interstellar medium and in Titan's atmosphere as well as to mitigate the emission of these carcinogens in our terrestrial environment. We have investigated the phenyl + acrylonitrile reaction mechanism between 600 and 1200 K in a hot microreactor. Radical intermediates (C9H8N˙), formed by addition, and closed-shell C9H7N products, formed by subsequent hydrogen elimination, are isomer-selectively identified using photoion mass-selected threshold photoelectron spectroscopy in conjunction with Franck-Condon simulations...
November 26, 2018: Physical Chemistry Chemical Physics: PCCP
Jagna Witek, Shuzhe Wang, Benjamin Schroeder, Robin Lingwood, Andreas Dounas, Hans Joerg Roth, Marianne Fouché, Markus Blatter, Oliver Lemke, Bettina G Keller, Sereina Riniker
Cyclization and selected backbone N-methylations are found to be often necessary but not sufficient conditions for peptidic drugs to have a good bioavailability. Thus, the design of cyclic peptides with good passive membrane permeability and good solubility remains a challenge. The backbone scaffold of a recently published series of cyclic decapeptides with six selected backbone N-methylations was designed to favor the adoption of a closed conformation with β-turns and four transannular hydrogen bonds. Although this conformation was indeed adopted by the peptides as determined by NMR measurements, substantial differences in the membrane permeability were observed...
November 20, 2018: Journal of Chemical Information and Modeling
Wolfgang Kemmler, Simon von Stengel, Daniel Schoene, Matthias Kohl
Age-related loss of muscle mass and function, also called sarcopenia, was recently added to the ICD-10 as an independent condition. However, declines in muscle mass and function are inevitable during the adulthood aging process. Concerning muscle strength as a crucial aspect of muscle function, maximum knee extension strength might be the most important physical parameter for independent living in the community. In this study, we aimed to determine the age-related decline in maximum isokinetic knee extension (MIES) and flexion strength (MIFS) in adult men...
2018: Frontiers in Physiology
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