Conformational and Quantitative Characterization of Oritavancin–Peptidoglycan Complexes in Whole Cells of Staphylococcus aureus by in Vivo 13C and 15N Labeling

2006 ◽  
Vol 357 (4) ◽  
pp. 1253-1262 ◽  
Author(s):  
Lynette Cegelski ◽  
Dirk Steuber ◽  
Anil K. Mehta ◽  
Daniel W. Kulp ◽  
Paul H. Axelsen ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Quantitative Characterization ◽  
Whole Cells ◽  
15N Labeling

scholarly journals Interpretation of the Directional Properties of Voluntarily Modulated Human Ankle Mechanical Impedance

2010 ◽  
Author(s):  
Patrick Ho ◽  
Hyunglae Lee ◽  
Mohammad A. Rastgaar ◽  
Hermano Igo Krebs ◽  
Neville Hogan
Keyword(s):  
Muscle Activation ◽  
Mechanical Impedance ◽  
In Vivo Studies ◽  
General Representation ◽  
Quantitative Characterization ◽  
Ankle Impedance ◽  
Human Ankle ◽  
Electromyographic Recording

This article presents the results of two in-vivo studies providing measurements of human static ankle mechanical impedance. Accurate measurements of ankle impedance when muscles were voluntarily activated were obtained using a therapeutic robot, Anklebot, and an electromyographic recording system. Important features of ankle impedance, and their variation with muscle activity, are discussed, including magnitude, symmetry and directions of minimum and maximum impedance. Voluntary muscle activation has a significant impact on ankle impedance, increasing it by up to a factor of three in our experiments. Furthermore, significant asymmetries and deviations from a linear two-spring model are present in many subjects, indicating that ankle impedance has a complex and individually idiosyncratic structure. We propose the use of Fourier series as a general representation, providing both insight and a precise quantitative characterization of human static ankle impedance.

scholarly journals Characterization of MazFSa, an Endoribonuclease from Staphylococcus aureus

2007 ◽  
Vol 189 (24) ◽  
pp. 8871-8879 ◽  
Author(s):  
Zhibiao Fu ◽  
Niles P. Donegan ◽  
Guido Memmi ◽  
Ambrose L. Cheung
Keyword(s):  
Staphylococcus Aureus ◽  
Environmental Stress Response ◽  
Binding Studies ◽  
Cell Growth Arrest ◽  
Consensus Sequences ◽  
E Coli ◽  
Endoribonuclease Activity

ABSTRACT The mazEF homologs of Staphylococcus aureus, designated mazEFsa , have been shown to cotranscribe with the sigB operon under stress conditions. In this study, we showed that MazEF Sa , as with their Escherichia coli counterparts, compose a toxin-antitoxin module wherein MazF Sa leads to rapid cell growth arrest and loss in viable CFU upon overexpression. MazF Sa is a novel sequence-specific endoribonuclease which cleaves mRNA to inhibit protein synthesis. Using ctpA mRNA as the model substrate both in vitro and in vivo, we demonstrated that MazF Sa cleaves single-strand RNA preferentially at the 5′ side of the first U or 3′ side of the second U residue within the consensus sequences VUUV′ (where V and V′ are A, C, or G and may or may not be identical). Binding studies confirmed that the antitoxin MazE Sa binds MazF Sa to form a complex to inhibit the endoribonuclease activity of MazF Sa . Contrary to the system in E. coli, exposure to selected antibiotics augmented mazEFsa transcription, akin to what one would anticipate from the environmental stress response of the sigB system. These data indicate that the mazEF system of S. aureus differs from the gram-negative counterparts with respect to mRNA cleavage specificity and antibiotic stresses.

scholarly journals Ultrasonograph and Clinical Quantitative Characterization of Tendinopathy by Modified Splitting in a Goat Model

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
A. Kavaguchi De Grandis ◽  
C. Boulocher ◽  
E. Viguier ◽  
T. Roger ◽  
S. Sawaya
Keyword(s):  
Flexor Tendon ◽  
Clinical Findings ◽  
Functional Score ◽  
Complementary Information ◽  
Quantitative Characterization ◽  
Cross Sectional ◽  
Anechoic Area ◽  
Surgically Induced

A tendinopathy is a clinical condition characterized by activity-related pain, focal tendons tenderness, and intratendinous imaging changes. This study characterizes a surgically induced tendinopathy in a goat model with a noninvasivein vivolongitudinal followup based on physical examination and US. Cross-sectional area (CSA) is the most objective feature for the evaluation of tendinopathy in correlation with clinical findings. The deep digital flexor tendon (DDFT) of the left hind limb of six goats was isolated and scarified by a modified splitting. Pain and lameness at walk and trot were evaluated. External width and thickness of tendon region were measured by calipers. CSA and the ratio lesion/tendon CSA were obtained at days 0, 7, 21, 42, and 84 by US. The highest value of global functional score was obtained at day 7, then decreased until day 40 and was not significantly different from day 0 at the end of the study. The external width recovered a normal value at the end of the study, but the external thickness was still significantly increased (P<0.05). Peritendinous oedema was observed at day 7, but intratendinous lesions were visible only at day 21 as a focal hypo to anechoic area. At day 84, two tendons still presented visible lesions. US examination was reproducible, specific, and provided complementary information to the global functional score. A standardized focal tendinopathy was induced in goats. This experimental model of focal tendinopathy could be used to study the effect of different treatments.

scholarly journals Identification and Characterization of Novel Antagonists of the CCR3 Receptor

2003 ◽  
Vol 8 (3) ◽  
pp. 324-331 ◽  
Author(s):  
Usha Warrior ◽  
Evelyn M. Mckeegan ◽  
Susan M. Rottinghaus ◽  
Lora Garcia ◽  
Linda Traphagen ◽  
...  
Keyword(s):  
Radioligand Binding ◽  
Parasitic Infections ◽  
Inhibitory Effects ◽  
Binding Interaction ◽  
Whole Cells ◽  
Eosinophil Migration ◽  
Allergic Disorders

Eotaxin, an inducer of eosinophil migration and activation, exerts its activity by binding to CCR3, the C-C chemokine receptor 3. An inhibitor of the eotaxin-CCR3 binding interaction may have potential as an anti-inflammatory drug for treatment of asthma, parasitic infections, and allergic disorders. A radioligand binding assay was developed using HEK cells transfected with CCR3, with 125I eotaxin as the ligand. Whole cells grown on polylysine-coated plates were used as the receptor source for the screen. Screening of more than 200,000 compounds with this assay yielded a number of screening hits, and of these, 2 active novel antagonists were identified. These compounds showed inhibitory effects on eosinophil chemotaxis in both in vitro and in vivo assays. ( Journal of Biomolecular Screening 2003:324-331)

scholarly journals Characterization of the Role of the Divalent Metal Ion-Dependent Transcriptional Repressor MntR in the Virulence of Staphylococcus aureus

2003 ◽  
Vol 71 (5) ◽  
pp. 2584-2590 ◽  
Author(s):  
Masaru Ando ◽  
Yukari C. Manabe ◽  
Paul J. Converse ◽  
Eishi Miyazaki ◽  
Robert Harrison ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Metal Ion ◽  
Mouse Skin ◽  
Wild Type ◽  
Divalent Metal Ion ◽  
Gel Shift Assay ◽  
Wild Type Control

ABSTRACT DtxR-type metal ion-dependent repressors, present in many bacterial pathogens, may regulate expression of virulence genes such as that encoding diphtheria toxin. SirR, a DtxR homologue initially identified in Staphylococcus epidermidis, governs the expression of the adjacent sitABC operon encoding a putative metal ion ABC transporter system. We identified a sirR homologue, mntR, in Staphylococcus aureus and demonstrated by gel shift assay that the corynebacterial repressor DtxR binds to the S. aureus mntABC operator in the presence of Fe2+ or Mn2+. Since a mutant DtxR, DtxR(E175K), functions as an iron-independent hyperrepressor in certain settings, we constructed a heterodiploid S. aureus strain expressing dtxR(E175K) from the native mntR promoter. Transcription of the S. aureus mntABC operon was repressed in the presence of Fe2+ or Mn2+ in wild-type and heterodiploid S. aureus strains. Under metal ion-limiting conditions, mntABC transcription was reduced but not abolished in S. aureus isolates expressing dtxR(E175K) compared with an isogenic control, suggesting that DtxR(E175K) binds the S. aureus MntR box in vivo. Under all conditions tested, mntABC transcription in the dtxR(E175K)-expressing strain was reduced relative to the isogenic control, indicating that DtxR(E175K) function was constitutively active. In the mouse skin abscess model, dtxR(E175K)-expressing S. aureus recombinants showed significantly reduced CFU levels compared with the isogenic wild-type control. We conclude that the S. aureus MntR box is recognized by corynebacterial DtxR proteins and thus belongs to the DtxR family of metal-dependent operator sites. Moreover, constitutive repression by DtxR(E175K) reduces the virulence of S. aureus in the mouse skin abscess model.

Sign in / Sign up

Export Citation Format

Share Document