Effect of laser generated shockwaves 1 on ex-vivo pigskin.

INTRODUCTION: Persistent bacterial infection prolongs hospitalizations, leading to increased healthcare costs. Treatment of these infections costs several billion dollars annually. Biofilm production is one mechanism by which bacteria become resistant. With the help of biofilms, bacteria withstand the host immune response and are much less susceptible to antibiotics. Currently, there is interest in the use of laser-generated shockwaves (LGS) to delaminate biofilm from infected wound surfaces; however, the safety of such an approach has not yet been established. Of particular concern are the thermal and mechanical effects of the shockwave treatment on the epidermis and the underlying collagen structure of the dermis. The present study is a preliminary investigation of the effect of LGS on freshly harvested ex vivo porcine skin tissue samples. MATERIALS AND METHODS: Tissue samples for investigation were harvested immediately post-mortem and treated with LGS within 30 minutes. Previous studies have shown that laser fluences between 100 and 500 mJ/pulse are capable of delaminating biofilms off a variety of surfaces, thus our preliminary investigation focused on this range of laser energy. For each sample, LGS were produced via laser irradiation of a thin layer (0.5 µm) of titanium sandwiched between a 50 and 100 µm thick layer of water glass and a 0.1 mm thick sheet of Mylar. The rapid thermal expansion of the irradiated titanium film generates a transient compressive wave that is coupled through a liquid layer to the surface of the ex vivo pigskin sample. Shocked samples were immediately fixed in formalin and prepared for histological analysis. A blinded pathologist evaluated and scored each section on the basis of its overall appearance (O) and presence of linear/slit-like spaces roughly parallel to the surface of the skin (S). The scores were given on a scale of 0-3. RESULTS: The present investigation revealed no visible difference between the tissue sections of the control sample and those that were subjected to laser-generated shockwaves. There was no relationship between the scores received by the samples and the energy with which they were shocked. CONCLUSION: Preliminary investigation into the safety of the LGS treatment for biofilm delamination appears promising. Additional investigation will continue on ex vivo porcine samples, followed by an in vivo animal trial to better understand the physiological response to LGS treatment.

Longitudinal changes in Chinese minority college students' health-related fitness: A multilevel latent growth curve modeling approach.

PURPOSE: The study aimed to test the overall changes of health-related fitness (HRF) in minority Chinese college students and to examine HRF differences in gender, race, and year in college. Method: Participants (n = 1320) were minority college students with more than two-thirds females (ie 76.1%), and Hui, Tibetan, and Mongolia consisted of 13.8%, 13.8%, and 11.2%, respectively. Student HRF was tracked for four years. Data were analyzed using multilevel latent growth curve modeling. Results: Muscular strength and endurance were the weakest component in minority college students' HRF, while body mass index was within the category of "excellent". Males outperformed female on all components of HRF. Conclusions: It is suggested that interventions concerning minority females' HRF and muscular strength and endurance for both genders be constructed and tested.

The Evaluation Point-of-Care Ultrasound in the Post-Anesthesia Unit-A Multicenter Prospective Observational Study.

INTRODUCTION: Point-of-care ultrasound (POCUS) is the most rapidly growing imaging modality for acute care. Despite increased use, there is still wide variability and less evidence regarding its clinical utility for the perioperative setting compared to other acute care settings. This study sought to demonstrate the impact of POCUS examinations for acute hypoxia and hypotension occurring in the post-anesthesia care unit (PACU) versus traditional bedside examinations. METHODS: This study was designed as a multi-center prospective observational study. Adult patients who experienced a reduced mean arterial blood pressure (MAP < 60mmHG) and/or a reduced oxygen saturation (SpO2 < 88%) in the PACU from 7AM to 4PM were targeted. POCUS was available or not for patient assessment based on PACU team training. All providers who performed POCUS exams received standardized training on cardiac and pulmonary POCUS. All POCUS exam findings were recorded on a standardized form and the number of suspected mechanisms to trigger the acute event were captured before and after the POCUS exam. PACU length of stay (minutes) across groups was the primary outcome. Results: In total, 128 patients were included in the study, with 92 patients receiving a POCUS exam. Comparison of PACU time between the POCUS group (median = 96.5 min) and no-POCUS groups (median = 120.5 min) demonstrated a reduction for the POCUS group, p = 0.019. Hospital length of stay and 30-day hospital readmission did not show a significant difference between groups. Finally, there was a reduction in the number of suspected diagnoses from before to after the POCUS examination for both pulmonary and cardiac exams, p-values < 0.001. CONCLUSIONS: Implementation of POCUS for assessment of acute hypotension and hypoxia in the PACU setting is associated with a reduced PACU length of stay and a reduction in suspected number of diagnoses.

Wide-field Raman imaging for bone detection in tissue.

Inappropriate bone growth in soft tissue can occur after trauma to a limb and can cause a disruption to the healing process. This is known as Heterotopic Ossification (HO) in which regions in the tissue start to mineralize and form microscopic bone-like structures. These structures continue to calcify and develop into large, non-functional bony masses that cause pain, limit limb movement, and expose the tissue to reoccurring infections; in the case of open wounds this can lead to amputation as a result of a failed wound. Both Magnetic Resonance Imaging (MRI) and X-ray imaging have poor sensitivity and specificity for the detection of HO, thus delaying therapy and leading to poor patient outcomes. We present a low-power, fast (1 frame per second) optical Raman imaging system with a large field of view (1 cm(2)) that can differentiate bone tissue from soft tissue without spectroscopy, this in contrast to conventional Raman microscopy systems. This capability may allow for the development of instrumentation which permits bedside diagnosis of HO.

Analysis of flexible substrates for clinical translation of laser-generated shockwave therapy.

Bacteria biofilms in chronically infected wounds significantly increase the burden of healthcare costs and resources for patients and clinics. Because biofilms are such an effective barrier to standard antibiotic treatment, new methods of therapy need to be developed to combat these infections. Our group has demonstrated the potential of using Laser Generated Shockwaves as a potential therapy to mechanically disrupt the bacterial biofilms covering the wound. Previous studies have used rigid silica glass as the shockwave propagation medium, which is not compatible with the intended clinical application. This paper describes the exploration of five candidate flexible plastic films to replace the glass substrate. Each material measured 0.254 mm thick and was used to generate shockwaves of varying intensities. Shockwave characterization was performed using a high-speed Michelson displacement interferometer and peak stress values obtained in the flexible substrates were compared to glass using one-way nested Analysis of Variance and Tukey HSD post-hoc analysis. Results demonstrate statistically significant differences between substrate material and indicate that polycarbonate achieves the highest peak stress for a given laser fluence suggesting that it is optimal for clinical applications.

Optical imaging for brain tissue characterization using relative fluorescence lifetime imaging.

An autofluorescence lifetime wide-field imaging system that can generate contrast in underlying tissue structures of normal and malignant brain tissue samples with video rate acquisition and processing time is presented. Images of the investigated tissues were acquired with high resolution (∼35 µm) using an algorithm to produce contrast based on differences in relative lifetimes. Sufficient contrast for delineation was produced without the computation of fluorescence decay times or Laguerre coefficients. The imaged tissues were sent for histological analysis that confirmed the detected imaged tissues morphological findings and correlations between relative lifetime maps and histology identified.