113 research outputs found
Handgrip Strength as a Predictor of Muscular Strength and Endurance: A Cross-sectional Study
Introduction: Reliable muscle strength measurement of
individual muscle groups is time-consuming and so it would
be convenient to have a single, quick and simple tool as an
indicator of the general muscle strength. Handgrip strength
might be an adequate measurement for generalised muscle
strength. It has a low cost and may be used in a time-efficient
manner in clinical setting.
Aim: To determine if a handgrip dynamometer test is a valid
predictor of both muscular strength and endurance and to
provide a gender specific reference charts for handgrip and
establish correlation between BMI and handgrip.
Materials and Methods: It was a cross-sectional study,
conducted from October 2017 to March 2018. Participants
included 30 college students, 10 males and 20 females of
18 to 25 year age group. BMI of all subjects were measured.
Handgrip strength was measured by adjustable handgrip
dynamometer. Horizontal Jump Test (HJT) and Vertical
Jump Test (VJT) were used to measure lower limb muscle
strength. To evaluate the strength of the trunk, one minute
curl-ups test was used. Aerobic power was measured by VO2
max Cooper’s test.
Results: Significant correlation found between handgrip
strength and HJT (r=0.8226, r2
=0.6767, p<0.05), handgrip
strength and VJT (r=0.6917, r2
=0.4764, p<0.05), handgrip
strength and VO2
max (r=0.7204, r2
=0.519, p<0.05), handgrip
strength and BMI (r=-0.1341, r2
=0.018, p<0.05), handgrip
strength and one minute curls-up test (r=0.4368, r2
=0.1908,
p<0.05). Although there was weak correlation of handgrip
strength with BMI and one minute curls-up test.
Conclusion: Handgrip strength can be an effective tool for
predicting muscular strength and endurance
Viscoelasticity and primitive path analysis of entangled polymer liquids: From f-actin to polyethylene
We combine computer simulations and scaling arguments to develop a unified
view of polymer entanglement based on the primitive path analysis (PPA) of the
microscopic topological state. Our results agree with experimentally measured
plateau moduli for three different polymer classes over a wide rangeof reduced
polymer densities: (i) semi-dilute theta solutions of synthetic polymers, (ii)
the corresponding dense melts above the glass transition or crystallization
temperature, and (iii) solutions of semi-flexible (bio)polymers such as f-actin
or suspensions of rodlike viruses. Together these systems cover the entire
range from loosely to tightly entangled polymers. In particular, we argue that
the primitive path analysis renormalizes a loosely to a tightly entangled
system and provide a new explanation of the successful Lin-Noolandi packing
conjecture for polymer melts.Comment: To appear in J. Chem. Phys
Dynamics of orientational ordering in fluid membranes
We study the dynamics of orientational phase ordering in fluid membranes.
Through numerical simulation we find an unusually slow coarsening of
topological texture, which is limited by subdiffusive propagation of membrane
curvature. The growth of the orientational correlation length obeys a
power law with in the late stage. We also discuss
defect profiles and correlation patterns in terms of long-range interaction
mediated by curvature elasticity.Comment: 5 pages, 3 figures (1 in color); Eq.(9) correcte
Translation affects YoeB and MazF messenger RNA interferase activities by different mechanisms
Prokaryotic toxin–antitoxin loci encode mRNA cleaving enzymes that inhibit translation. Two types are known: those that cleave mRNA codons at the ribosomal A site and those that cleave any RNA site specifically. RelE of Escherichia coli cleaves mRNA at the ribosomal A site in vivo and in vitro but does not cleave pure RNA in vitro. RelE exhibits an incomplete RNase fold that may explain why RelE requires its substrate mRNA to presented by the ribosome. In contrast, RelE homologue YoeB has a complete RNase fold and cleaves RNA independently of ribosomes in vitro. Here, we show that YoeB cleavage of mRNA is strictly dependent on translation of the mRNA in vivo. Non-translated model mRNAs were not cleaved whereas the corresponding wild-type mRNAs were cleaved efficiently. Model mRNAs carrying frameshift mutations exhibited a YoeB-mediated cleavage pattern consistent with the reading frameshift thus giving strong evidence that YoeB cleavage specificity was determined by the translational reading frame. In contrast, site-specific mRNA cleavage by MazF occurred independently of translation. In one case, translation seriously influenced MazF cleavage efficiency, thus solving a previous apparent paradox. We propose that translation enhances MazF-mediated cleavage of mRNA by destabilization of the mRNA secondary structure
Soft and non-soft structural transitions in disordered nematic networks
Properties of disordered nematic elastomers and gels are theoretically
investigated with emphasis on the roles of non-local elastic interactions and
crosslinking conditions. Networks originally crosslinked in the isotropic phase
lose their long-range orientational order by the action of quenched random
stresses, which we incorporate into the affine-deformation model of nematic
rubber elasticity. We present a detailed picture of mechanical quasi-Goldstone
modes, which accounts for an almost completely soft polydomain-monodomain (P-M)
transition under strain as well as a ``four-leaf clover'' pattern in
depolarized light scattering intensity. Dynamical relaxation of the domain
structure is studied using a simple model. The peak wavenumber of the structure
factor obeys a power-law-type slow kinetics and goes to zero in true mechanical
equilibrium. The effect of quenched disorder on director fluctuation in the
monodomain state is analyzed. The random frozen contribution to the fluctuation
amplitude dominates the thermal one, at long wavelengths and near the P-M
transition threshold. We also study networks obtained by crosslinking
polydomain nematic polymer melts. The memory of initial director configuration
acts as correlated and strong quenched disorder, which renders the P-M
transition non-soft. The spatial distribution of the elastic free energy is
strongly dehomogenized by external strain, in contrast to the case of
isotropically crosslinked networks.Comment: 19 pages, 15 EPS figure
Chemical Stability of the Botanical Drug Substance Crofelemer: A Model System for Comparative Characterization of Complex Mixture Drugs
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.As the second of a 3-part series of articles in this issue concerning the development of a mathematical model for comparative characterization of complex mixture drugs using crofelemer (CF) as a model compound, this work focuses on the evaluation of the chemical stability profile of CF. CF is a biopolymer containing a mixture of proanthocyanidin oligomers which are primarily composed of gallocatechin with a small contribution from catechin. CF extracted from drug product was subjected to molecular weight–based fractionation and thiolysis. Temperature stress and metal-catalyzed oxidation were selected for accelerated and forced degradation studies. Stressed CF samples were size fractionated, thiolyzed, and analyzed with a combination of negative-ion electrospray ionization mass spectrometry (ESI-MS) and reversed-phase-HPLC with UV absorption and fluorescence detection. We further analyzed the chemical stability data sets for various CF samples generated from reversed-phase-HPLC-UV and ESI-MS using data-mining and machine learning approaches. In particular, calculations based on mutual information of over 800,000 data points in the ESI-MS analytical data set revealed specific CF cleavage and degradation products that were differentially generated under specific storage/degradation conditions, which were not initially identified using traditional analysis of the ESI-MS results
Comparative Characterization of Crofelemer Samples Using Data Mining and Machine Learning Approaches With Analytical Stability Data Sets
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.There is growing interest in generating physicochemical and biological analytical data sets to compare complex mixture drugs, for example, products from different manufacturers. In this work, we compare various crofelemer samples prepared from a single lot by filtration with varying molecular weight cutoffs combined with incubation for different times at different temperatures. The 2 preceding articles describe experimental data sets generated from analytical characterization of fractionated and degraded crofelemer samples. In this work, we use data mining techniques such as principal component analysis and mutual information scores to help visualize the data and determine discriminatory regions within these large data sets. The mutual information score identifies chemical signatures that differentiate crofelemer samples. These signatures, in many cases, would likely be missed by traditional data analysis tools. We also found that supervised learning classifiers robustly discriminate samples with around 99% classification accuracy, indicating that mathematical models of these physicochemical data sets are capable of identifying even subtle differences in crofelemer samples. Data mining and machine learning techniques can thus identify fingerprint-type attributes of complex mixture drugs that may be used for comparative characterization of products
The Phosphatomes of the Multicellular Myxobacteria Myxococcus xanthus and Sorangium cellulosum in Comparison with Other Prokaryotic Genomes
BACKGROUND: Analysis of the complete genomes from the multicellular myxobacteria Myxococcus xanthus and Sorangium cellulosum identified the highest number of eukaryotic-like protein kinases (ELKs) compared to all other genomes analyzed. High numbers of protein phosphatases (PPs) could therefore be anticipated, as reversible protein phosphorylation is a major regulation mechanism of fundamental biological processes. METHODOLOGY: Here we report an intensive analysis of the phosphatomes of M. xanthus and S. cellulosum in which we constructed phylogenetic trees to position these sequences relative to PPs from other prokaryotic organisms. PRINCIPAL FINDINGS: PREDOMINANT OBSERVATIONS WERE: (i) M. xanthus and S. cellulosum possess predominantly Ser/Thr PPs; (ii) S. cellulosum encodes the highest number of PP2c-type phosphatases so far reported for a prokaryotic organism; (iii) in contrast to M. xanthus only S. cellulosum encodes high numbers of SpoIIE-like PPs; (iv) there is a significant lack of synteny among M. xanthus and S. cellulosum, and (v) the degree of co-organization between kinase and phosphatase genes is extremely low in these myxobacterial genomes. CONCLUSIONS: We conclude that there has been a greater expansion of ELKs than PPs in multicellular myxobacteria
The Myxococcus xanthus Two-Component System CorSR Regulates Expression of a Gene Cluster Involved in Maintaining Copper Tolerance during Growth and Development
Myxococcus xanthus is a soil-dwelling member of the δ–Proteobacteria that exhibits a complex developmental cycle upon starvation. Development comprises aggregation and differentiation into environmentally resistant myxospores in an environment that includes fluctuations in metal ion concentrations. While copper is essential for M. xanthus cells because several housekeeping enzymes use it as a cofactor, high copper concentrations are toxic. These opposing effects force cells to maintain a tight copper homeostasis. A plethora of paralogous genes involved in copper detoxification, all of which are differentially regulated, have been reported in M. xanthus. The use of in-frame deletion mutants and fusions with the reporter gene lacZ has allowed the identification of a two-component system, CorSR, that modulates the expression of an operon termed curA consisting of nine genes whose expression slowly increases after metal addition, reaching a plateau. Transcriptional regulation of this operon is complex because transcription can be initiated at different promoters and by different types of regulators. These genes confer copper tolerance during growth and development. Copper induces carotenoid production in a ΔcorSR mutant at lower concentrations than with the wild-type strain due to lack of expression of a gene product resembling subunit III of cbb3-type cytochrome c oxidase. This data may explain why copper induces carotenoid biosynthesis at suboptimal rather than optimal growth conditions in wild-type strains.This work has been funded by the Spanish Government (grants CSD2009-00006 and BFU2012-33248, 70% funded by FEDER). This work was also supported by the National Institute of General Medical Science of the National Institutes of Health under award number R01GM095826 to LJS, and by the National Science Foundation under award number MCB0742976 to LJS. JMD and JP received a fellowship from Junta de Andalucía to do some work at University of Georgia
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