Draft genome sequence and biofilm production of a carbapenemase-producing Klebsiella pneumoniae (KpR405) sequence type 405 strain isolated in Italy

Rapid identification and characterization of multidrug-resistant Klebsiella pneumoniae strains is essential to diagnose severe infections in patients. In clinical routine practice, K. pneumoniae is frequently identified and characterized for outbreak investigation. Pulsed-field gel electrophoresis or multilocus sequence typing could be used, but, unfortunately, these methods are time-consuming, laborious, expensive, and do not provide any information about the presence of resistance and virulence genes. In recent years, the decreasing cost of next-generation sequencing and its easy use have led to it being considered a useful method, not only for outbreak surveillance but also for rapid identification and evaluation, in a single step, of virulence factors and resistance genes. Carbapenem-resistant strains of K. pneumoniae have become endemic in Italy, and in these strains the ability to form biofilms, communities of bacteria fixed in an extracellular matrix, can defend the pathogen from the host immune response as well as from antibiotics, improving its persistence in epithelial tissues and on medical device surfaces

Three single loops enhance the biomechanical behavior of the transtibial pull-out technique for posterior meniscal root repair.

Purpose: To investigate the effect of applying an additional suture to enhance the biomechanical behavior of the suture\u2013meniscus construct used during the transtibial pull- out repair technique. Methods: A total of 20 fresh-frozen porcine tibiae with intact medial menisci were used. In one half of all speci- mens (N = 10), two non-absorbable sutures were passed directly over the meniscal root from the tibia side of the meniscus to the femoral side (2SS). In other ten specimens, three sutures were passed over the meniscal root (3SS). All specimens were subjected to cyclic loading followed by load-to-failure testing. Displacement of the construct was recorded at 100, 500, and 1000 cycles. Further, stiffness (500\u20131000 cycles) and ultimate load and modes of failure of the suture\u2013meniscus construct were also recorded. Results: There was no statistically significant difference between the Group 2SS and Group 3SS at the 1st (1.6\ub10.7vs1.4\ub10.4mm)andthe100thcycle(2\ub10.7 vs 1.8 \ub1 0.4 mm). At 500 and 1000 cycles, the 2SS fixa- tion technique resulted in significantly more displacement than the 3SS fixation technique (2.8 \ub1 0.6 vs 2.3 \ub1 0.5 mm; 3.1 \ub1 0.7 vs 2.5 \ub1 0.5 mm) (p\0.05). No differences between two groups were noted concerning ultimate load to failure and stiffness (500\u20131000 cycles). Conclusion: Three single sutures technique provided superior biomechanical properties compared with the two single sutures technique during the conducted fatigue tests. Clinical relevance Applying three simple stitches during meniscal root repair might be beneficial for healing of the posterior meniscal root, potentially reducing the post-op- erative immobilization time

Similar biomechanical properties of four tripled tendon graft models for ACL reconstruction

Purpose: The present study tested and compared the biomechanical properties of four different triplicate graft tendon techniques. Methods: 32 tripled tendons from the common extensor muscle of bovine fingers were tested on a material testing machine, passing the end loop over a metal rod of a clevis connected to the load cell on the upper side, and fixing the lower end to a clamp. The samples were divided into four groups: (A) tripled with a free end sutured only to one of the two fixed bundles (B) tripled with a free end positioned between the two fixed strands and sutured to both (C) tripled with an S-shape and all the three strands sutured together at the upper and lower extremities of the graft (D) partially quadrupled with the free end sutured together with the other three bundles at the upper extremity. Each sample was pretensioned at 50 N for 10 min and then subjected to 1000 load control cycles between 50 and 250 N. Finally, each sample was subjected to a load to failure test. Authors also present some preliminary results on the feasibility of a non-contact and full-field Thermoelastic Stress Analysis technique, based on Infrared Thermography, to evaluate the level of stress on the whole graft, and hence on each strand, during fatigue loading. Results: Eighty five percent of the samples failed at the level of the clamp. The cyclical elongation progressively decreased in all the samples and there was a simultaneous increase in stiffness. An increased stiffness was noted between Group 2 vs Group 3 and Group 2 vs Group 4 at the 500th and 1000th cycle. The failure loads were as follows: (a) 569.10 N, (b) 632.28 N, (c) 571.68 N, (d) 616.95 N. None of the parameters showed a statistically significant difference between the four groups. Conclusion: This study reported similar biomechanical behavior of four different models of tripled grafts suitable for ACL reconstruction. In addition, the biomechanics of overall tripled tendon grafts seems more affected by the viscoelastic property of the tendon itself rather than the preparation method

Production of a double layer scaffold for the \u201con demand\u201d release of fibroblast-like limbal stem cells

The production and characterization of a double layer scaffold, to be used as a system for the \u201con demand\u201d release of corneal limbal stem cells are here reported. The devices used in the clinics and proposed so far in the scientific literature, for the release of corneal stem cells in the treatment of limbal stem cell deficiency, cannot control the in vivo space-time release of cells since the biomaterial of which they are composed is devoid of stimuli responsiveness features. Our approach was to produce a scaffold composed of two different polymeric layers that give the device the appropriate mechanical properties to be placed on the ocular surface and the possibility of releasing the stem cells following a non-invasive and cell-friendly treatment. This device consists of an electrospun micro fibrillar scaffold of poly-L-lactic acid coated by a polymeric film based on an amphiphilic derivative of hyaluronic acid sensitive to the ionic strength of the external medium and to the presence of a complexing agent. The latter represents the \u201csacrificial\u201d cell containing layer of the scaffold that can be dissolved \u201con demand\u201d by the treatment with a solution of cyclodextrins. The rapid removal of the external polymeric film from the device is exploited to control the space-time release of the cells. In vitro and ex vivo experiments showed that fibroblast-like limbal stem cells cultured on the scaffold without the use of the feeder layer maintained their characteristics of stem cells and can be released \u201con demand\u201d on the culture well coated with Matrigel or on the decellularized bovine cornea, respectively

Type-II transmembrane prolyl dipeptidases and matrix metalloproteinases in membrane vesicles of active endothelial cells

Conclusions: Endothelia cells in sparse culture are migratory and increase the production of gelatinases of serine- and metallo-classes in membrane vesicles. Collectively, proteases associated with membrane vesicles degrade extracellular matrix components including type-I and type-IV collagens, laminin and fibronectin. Inhibitor studies suggest the existence of small gelatinases that were derived from these serine- and metallo-proteases. Thus, further studies are warranted to demonstrate the cooperative action of metallo- and serine proteases on cell surfaces and in extracellular vesicles during endothelial cell migration in 3D collagenous matrices, and potential proteolytic activation mechanism for these cell surface proteases