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1.
J Infect Chemother ; 25(6): 413-422, 2019 Jun.
Article in English | MEDLINE | ID: mdl-30905628

ABSTRACT

The Japanese Surveillance Committee conducted a second nationwide surveillance of antimicrobial susceptibility patterns of uropathogens responsible for acute uncomplicated cystitis (AUC) in premenopausal patients aged 16-40 years old at 31 hospitals throughout Japan from March 2015 to February 2016. In this study, the susceptibility of causative bacteria (Escherichia coli, Klebsiella pneumoniae, Staphylococcus saprophyticus) for various antimicrobial agents was investigated by isolation and culturing of organisms obtained from urine samples. In total, 324 strains were isolated from 361 patients, including E. coli (n = 220, 67.9%), S. saprophyticus (n = 36, 11.1%), and K. pneumoniae (n = 7, 2.2%). The minimum inhibitory concentrations (MICs) of 20 antibacterial agents for these strains were determined according to the Clinical and Laboratory Standards Institute (CLSI) manual. At least 93% of the E. coli isolates showed susceptibility to fluoroquinolones and cephalosporins, whereas 100% of the S. saprophyticus isolates showed susceptibility to fluoroquinolones and aminoglycosides. The proportions of fluoroquinolone-resistant and extended-spectrum ß-lactamase (ESBL)-producing E. coli strains were 6.4% (13/220) and 4.1% (9/220), respectively. The antimicrobial susceptibility of K. pneumoniae was retained during the surveillance period, while no multidrug-resistant strains were identified. In summary, antimicrobial susceptibility results of our second nationwide surveillance did not differ significantly from those of the first surveillance. Especially the numbers of fluoroquinolone-resistant and ESBL-producing E. coli strains were not increased in premenopausal patients with AUC in Japan.


Subject(s)
Anti-Bacterial Agents/pharmacology , Cystitis/drug therapy , Drug Resistance, Multiple, Bacterial , Escherichia coli/drug effects , Klebsiella pneumoniae/drug effects , Staphylococcus saprophyticus/drug effects , Adolescent , Adult , Anti-Bacterial Agents/therapeutic use , Cystitis/epidemiology , Cystitis/microbiology , Epidemiological Monitoring , Escherichia coli/isolation & purification , Escherichia coli/metabolism , Female , Humans , Japan , Klebsiella pneumoniae/isolation & purification , Klebsiella pneumoniae/metabolism , Male , Microbial Sensitivity Tests , Middle Aged , Staphylococcus saprophyticus/isolation & purification , Staphylococcus saprophyticus/metabolism , Young Adult , beta-Lactamases/metabolism
2.
Biochem Biophys Res Commun ; 420(4): 710-3, 2012 Apr 20.
Article in English | MEDLINE | ID: mdl-22366037

ABSTRACT

Actin filaments have a double-helix structure consisting of globular actin molecules. In many mechanical cellular activities, such as cell movement, division, and shape control, modulation of the extensional and torsional dynamics of the filament has been linked to regulatory actin-binding protein functions. Therefore, it is important to quantitatively evaluate extension-torsion coupling of filament to better understand the actin filament dynamics. In the present study, the extension-torsion coupling was investigated using molecular dynamics simulations. We constructed a model for the actin filament consisting of 14 actin subunits in an ionic solvent as a minimal functional unit, and analyzed longitudinal and twisting Brownian motions of the filament. We then derived the expected value of energy associated with extension and torsion at equilibrium, and evaluated the extension-torsion stiffness of the filament from the thermal fluctuations obtained from the MD simulations. The results demonstrated that as the analyzed sampling-window duration was increased, the extension-torsion coupling stiffness evaluated on a nanosecond scale tended to converge to a value of 7.6×10(-11) N. The results obtained from this study will contribute to the understanding of biomechanical events, under mechanical tension and torque, involving extension-torsion coupling of filaments.


Subject(s)
Actin Cytoskeleton/chemistry , Molecular Dynamics Simulation , Tensile Strength , Crystallography, X-Ray , Protein Conformation
3.
Biomech Model Mechanobiol ; 11(3-4): 291-302, 2012 Mar.
Article in English | MEDLINE | ID: mdl-21614531

ABSTRACT

The adaptive structure and functional changes of the actin cytoskeleton are induced by its mechanical behavior at various temporal and spatial scales. In particular, the mechanical behaviors at different scales play important roles in the mechanical functions of various cells, and these multiscale phenomena require clarification. To establish a milestone toward achieving multiscale modeling and simulation, this paper reviews mathematical analyses and simulation methods applied to the mechanics of the filamentous actin cytoskeleton. The actin cytoskeleton demonstrates characteristic behaviors at every temporal and spatial scale, and mathematical models and simulation methods can be applied to each level of actin cytoskeletal structure ranging from the molecular to the network level. This paper considers studies on mathematical models and simulation methods based on the molecular dynamics, coarse-graining, and continuum dynamics approaches. Every temporal and spatial scale of actin cytoskeletal structure is considered, and it is expected that discrete and continuum dynamics ranging from functional expression at the molecular level to macroscopic functional expression at the whole cell level will be developed and applied to multiscale modeling and simulation.


Subject(s)
Actins/chemistry , Biophysics/methods , Cytoskeleton/metabolism , Animals , Biomechanical Phenomena , Computer Simulation , Dimerization , Humans , Microfilament Proteins/metabolism , Models, Molecular , Models, Theoretical , Molecular Conformation , Molecular Dynamics Simulation , Solvents/chemistry , Stress, Mechanical , Time Factors
4.
J Biomech ; 44(9): 1776-81, 2011 Jun 03.
Article in English | MEDLINE | ID: mdl-21536289

ABSTRACT

Actin filaments are the most abundant components of the cellular cytoskeleton, and play critical roles in various cellular functions such as migration, division and shape control. In these activities, mechanical tension causes structural changes in the double-helical structure of the actin filament, which is a key modulator of cytoskeletal reorganization. This study performed large-scale molecular dynamics (MD) and steered MD simulations to quantitatively analyze the effects of tensile force on the mechanical behavior of actin filaments. The results revealed that when a tensile force of 200pN was applied to a filament consisting of 14 actin subunits, the twist angle of the filament decreased by approximately 20°, corresponding to a rotation of approximately -2° per subunit, representing a critical structural change in actin filaments. Based on these structural changes, the variance in filament length and twist angle was found to decrease, leading to increases in extensional and torsional stiffness. Torsional stiffness increased significantly under the tensile condition, and the ratio of filament stiffness under tensile force to that under no external force increased significantly on longer temporal scales. The results obtained from this study contribute to the understanding of mechano-chemical interactions concerning actin dynamics, showing that increased tensile force in the filament prevents actin regulatory proteins from binding to the filament.


Subject(s)
Actin Cytoskeleton/chemistry , Adenosine Diphosphate/chemistry , Animals , Biomechanical Phenomena , Chickens , Computer Simulation , Cytoskeleton/metabolism , Humans , Models, Biological , Molecular Conformation , Molecular Dynamics Simulation , Protein Binding , Stress, Mechanical , Tensile Strength , Time Factors
5.
J Biomech ; 43(16): 3162-7, 2010 Dec 01.
Article in English | MEDLINE | ID: mdl-20825942

ABSTRACT

It is essential to investigate the mechanical behaviour of cytoskeletal actin filaments in order to understand their critical role as mechanical components in various cellular functional activities. These actin filaments consisting of monomeric molecules function in the thermal fluctuations. Hence, it is important to understand their mechanical behaviour on the microscopic scale by comparing the stiffness based on thermal fluctuations with the one experimentally measured on the macroscopic scale. In this study, we perform a large-scale molecular dynamics (MD) simulation for a half-turn structure of an actin filament. We analyse its longitudinal and twisting Brownian motions in equilibrium and evaluated its apparent extensional and torsional stiffness on the nanosecond scale. Upon increasing the sampling-window durations for analysis, the apparent stiffness gradually decreases and exhibits a trend to converge to a value that is close to the experimental value. This suggests that by extrapolating the data obtained in the MD analysis, we can estimate the experimentally determined stiffness on the microsecond to millisecond scales. For shorter temporal scales, the apparent stiffness is larger than experimental values, indicating that fast, local motions of the molecular structure are dominant. To quantify the local structural changes within the filament on the nanosecond scale and investigate the molecular mechanisms, such as the binding of the actin-regulatory proteins to the filaments, it is preferable to analyse the mechanical behaviour on the nanometre and nanosecond scales using MD simulation.


Subject(s)
Actin Cytoskeleton/chemistry , Actin Cytoskeleton/physiology , Animals , Biomechanical Phenomena , Computer Simulation , Crystallography, X-Ray , In Vitro Techniques , Models, Molecular , Molecular Dynamics Simulation , Protein Structure, Secondary , Rabbits
6.
J Orthop Trauma ; 19(4): 282-5, 2005 Apr.
Article in English | MEDLINE | ID: mdl-15795579

ABSTRACT

Isolated dislocation of the hamate bone and pisiform bone is rare. We describe the simultaneous complete dislocation of both the hamate and pisiform bones in a 27-year-old man who crushed his right hand in a rolling press. An open reduction and internal fixation with Kirschner wires was performed. Four weeks later, the Kirschner wires were removed and rehabilitation was started. At 6 months follow-up, the patient had minimal pain and full range of motion in the affected wrist joint and fingers. However, grip strength was 50% compared to his unaffected left hand, and sensation of the ulnar nerve area was reduced to almost 30% of that of his left hand. It appears that the ulnar nerve injury was the largest contributing factor to the poor outcome of our patient. Evaluation of soft-tissue injuries, especially nerve injury, is important in the treatment of complex carpal dislocations.


Subject(s)
Carpal Bones/injuries , Joint Dislocations/surgery , Wrist Injuries/surgery , Adult , Bone Wires , Fracture Fixation, Internal , Humans , Joint Dislocations/diagnostic imaging , Joint Dislocations/physiopathology , Male , Radiography , Wrist Injuries/diagnostic imaging , Wrist Injuries/physiopathology
7.
Int J Urol ; 9(5): 241-6, 2002 May.
Article in English | MEDLINE | ID: mdl-12189603

ABSTRACT

BACKGROUND: We determined the long-term result of our percutaneous antegrade balloon dilation technique performed for adult patients with ureterointestinal anastomotic stricture between 1992 and 1997. METHODS: Balloon dilation was performed on 13 ureterointestinal anastomotic structures in 10 patients. After a nephrostomy was performed, a guide wire was introduced into the intestinal loop through the stenotic portion under direct observation using a ureterorenoscope. Dilation was performed using the Olbert balloon dilator (30-Fr) inserted along a guide wire into the stenotic portion. A 20-Fr or 22-Fr multihole catheter was left for approximately 6 weeks. No major complications were encountered during or after these procedures. After removal of the indwelling catheters, the progress of each patient was followed fo rat least 14 months. RESULTS: Additional dilation was necessary in three of 10 patients for the recurrent stricture. The balloon dilation was ineffective in two patients with a long stenosis of the ureter or a previous history of radiation therapy for uterine cancer. Eight of 10 patients showed satisfactory outcomes during the mean follow-up period of 47.1 months. CONCLUSIONS: Based on these results, we believe that the balloon dilation could be the first line of treatment for strictures of uro-digestive anastomosis, except for some patients with a long stenosis or a previous history of intrapelvic radiation.


Subject(s)
Catheterization , Intestinal Obstruction/therapy , Ureteral Diseases/therapy , Adult , Aged , Female , Follow-Up Studies , Humans , Male , Middle Aged , Postoperative Complications/therapy , Treatment Outcome , Ureteroscopy , Urinary Diversion
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