Fingertip ultrasound evaluation of umbilical catheter position in the neonatal intensive care unit compared to conventional ultrasound radiography: a preliminary investigation.

OBJECTIVE: The purpose of the study is to compare conventional linear and fingertip ultrasound transducers, for the evaluation of umbilical catheters, with radiography. Fingertip ultrasound transducers have the potential to simplify sonographic examination due to their small size and ability to fit on a finger. STUDY DESIGN: A prospective, IRB approved comparative study was performed. Linear and fingertip sonographic images were obtained around the same time as a radiograph in neonates with umbilical catheters by two board certified pediatric radiologists and a radiology resident. The positions of catheters were then compared across all three modalities. RESULT: A total of 41 catheters were evaluated, which included 14 arterial and 27 venous catheters. Two venous catheters were not identified by the linear transducer and one arterial catheter tip was not identified by the fingertip transducer. CONCLUSION: A fingertip ultrasound probe can be used to evaluate umbilical catheter positioning for potentially faster sonographic examination and decrease the need for repeated radiation.

An evaluation of the impact of clinical bacterial isolates on epithelial cell monolayer integrity by the electric Cell-Substrate Impedance Sensing (ECIS) method.

Virulence is the relative capacity of a pathogenic microorganism to cause damage in susceptible host cells such as those found in airway passages and the gut. In this study, the effect of clinical bacterial isolates on the monolayer integrity of cultured human alveolar basal epithelial cells (A549) was evaluated using the Electric Cell-Substrate Impedance Sensing (ECIS) system. ECIS is a morphological biosensor which records electrical properties of cell-covered microelectrodes in an AC circuit including impedance (ohm), resistance (ohm), and capacitance (µFarad). In the current study, fluctuations in the electrical properties of cell-covered microelectrodes reflect dynamic changes in cell morphology resulting from disrupted cell monolayers following exposure to bacteria. Using the ECIS system, real-time changes of cell morphology and disruption of monolayer integrity of cell-cultures in vitro were revealed for A549 cells infected with either Pseudomonas aeruginosa, ESBL Escherichia coli, Staphylococcus aureus (MRSA), or Enterococcus (VRE). We determined empirically that the optimal signal response was obtained for resistance (ohm) measurements at 4000 hertz. Following infection of A549 cells, the data revealed that Pseudomonas aeruginosa resulted in little change in microelectrode resistance (ohm @4 kHz) as compared to pathogen-free controls within the first 12 h. In contrast, E. coli, MRSA, and VRE caused significant changes in electrode resistance (ohm @4 kHz) values in the infected cells compared to controls over the first 5 h. Resistance (ohm @4 kHz) changes were also observed in cell monolayers infected with different bacterial concentrations for all isolates over 24 h. The highest concentration of bacteria caused the measured resistance (ohm @4 kHz) to drop faster than its' immediate lower concentration, suggesting a dose-dependent effect. Compared to live bacteria, cells exposed to heat-killed bacteria did not show significant changes in resistance (ohm @4 kHz) over 48 h post-exposure. Functionally, cytokine responses were different between cells treated with live and heat-killed bacteria. Of note, live bacteria induced IFNγ, IL-13, and IL-1ß production in A549 cells, whereas heat-killed bacteria induced IL-8 production suggesting a differential interaction with cells that could reveal the underlying causes of resistance (ohm @4 kHz) changes. Our findings indicate that ECIS provides a means to quantify, automate, and measure bacterial virulence, which may have broader implications governing the course of treatment compared to traditional methods alone.

Bone Marrow-Derived Mesenchymal Stem Cells Enhance Bacterial Clearance and Preserve Bioprosthetic Integrity in a Model of Mesh Infection.

BACKGROUND: The reported incidence of mesh infection in contaminated operative fields is as high as 30% regardless of the material used. Recently, mesenchymal stem cells (MSCs) have been shown to possess favorable immunomodulatory properties and improve tissue incorporation when seeded onto bioprosthetics. The aim of this study was to evaluate whether seeding noncrosslinked bovine pericardium (Veritas Collagen Matrix) with allogeneic bone marrow-derived MSCs improves infection resistance in vivo after inoculation with Escherichia coli (E. coli). METHODS: Rat bone marrow-derived MSCs at passage 3 were seeded onto bovine pericardium and cultured for 7 days before implantation. Additional rats (n = 24) were implanted subcutaneously with MSC-seeded or unseeded mesh and inoculated with 7 × 10(5) colony-forming units of E. coli or saline before wound closure (group 1, unseeded mesh/saline; group 2, unseeded mesh/E. coli; group 3, MSC-seeded mesh/E. coli; 8 rats per group). Meshes were explanted at 4 weeks and underwent microbiologic and histologic analyses. RESULTS: MSC-seeded meshes inoculated with E. coli demonstrated superior bacterial clearance and preservation of mesh integrity compared with E. coli-inoculated unseeded meshes (87.5% versus 0% clearance; p = 0.001). Complete mesh degradation concurrent with abscess formation was observed in 100% of rats in the unseeded/E. coli group, which is in contrast to 12.5% of rats in the MSC-seeded/E. coli group. Histologic evaluation determined that remodeling characteristics of E. coli-inoculated MSC-seeded meshes were similar to those of uninfected meshes 4 weeks after implantation. CONCLUSIONS: Augmenting a bioprosthetic material with stem cells seems to markedly enhance resistance to bacterial infection in vivo and preserve mesh integrity.

Development of real-time assays for impedance-based detection of microbial double-stranded DNA targets: optimization and data analysis.

A real-time, label free assay was developed for microbial detection, utilizing double-stranded DNA targets and employing the next generation of an impedimetric sensor array platform designed by Sharp Laboratories of America (SLA). Real-time curves of the impedimetric signal response were obtained at fixed frequency and voltage for target binding to oligonucleotide probes attached to the sensor array surface. Kinetic parameters of these curves were analyzed by the integrated data analysis package for signal quantification. Non-specific binding presented a major challenge for assay development, and required assay optimization. For this, differences were maximized between binding curve kinetic parameters for probes binding to complementary targets versus non-target controls. Variables manipulated for assay optimization included target concentration, hybridization temperature, buffer concentration, and the use of surfactants. Our results showed that (i) different target-probe combinations required optimization of specific sets of variables; (ii) for each assay condition, the optimum range was relatively narrow, and had to be determined empirically; and (iii) outside of the optimum range, the assay could not distinguish between specific and non-specific binding. For each target-probe combination evaluated, conditions resulting in good separation between specific and non-specific binding signals were established, generating high confidence in the SLA impedimetric dsDNA assay results.

Different outcomes in urethral reconstruction using elastin and collagen patches and conduits in rabbits.

OBJECTIVES: To study the feasibility of urethral reconstruction with two urethroplasty techniques using an elastin and collagen heterograft in rabbits. MATERIALS AND METHODS: Fifty-two male rabbits were studied. Two types of injury, (1) a 1.5 x 0.6 cm2 semicircumferential defect; (2) a 1.5 cm segmental defect of the penile urethra, were created and repaired using size-matched elastin and collagen patches or tubed conduits. Urethral repair by primary closure for the type 1 injury and a tubularized autologous bladder mucosal graft for the type 2 injury served as controls. At 3 months, urethral diameter was measured with retrograde urethrography. The animals were then euthanized for histological examination. RESULTS: The postoperative complication rate was significantly higher in the urethral reconstructions using tubed collagen (83%) and elastin (50%) grafts compared to the patch onlay grafts (p = 0.001 for collagen and p = 0.01 for elastin) and tubularized ABM (10%, p = 0.003 and 0.05, respectively). At the type 2 injury site, a dense circumferential fibrosis developed after all repairs. Only minimal ventral fibrosis presented in the type 1 injury repair. The intensity of chronic inflammation and fibrosis was greatest when collagen was used for the urethral repair. In the elastin urethral repairs the urethral diameter decreased significantly for the tubed repair compared to the patch onlay (p = 0.02). CONCLUSION: Urethral injury repair using elastin and collagen biomaterials is feasible in the rabbit model. The results of onlay urethroplasty using the elastin and collagen patches are significantly superior to those using the elastin and collagen tubed conduits.