Satya Amirapu

Intramucosal bacterial microcolonies exist in chronic rhinosinusitis without inducing a local immune response.

Background Although chronic rhinosinusitis (CRS) causes very significant morbidity, much about its pathogenesis remains uncertain. Recent studies have identified polymicrobial biofilms on the surface of sinus mucosa and Staphylococcus aureus within the sinus mucosa of patients with CRS, both with and without nasal polyps. The pathogenic implications of intramucosal bacteria in CRS are unknown. This study was designed to determine the prevalence and species of bacterial colonies within the sinus mucosa of adult patients with and without CRS and to describe the relationship of these bacterial colonies to the host immune response. Methods Sinus mucosa from patients with and without CRS was examined using Gram and Giemsa staining, immunohistochemistry, bacterial culture, and fluorescence in situ hybridization techniques. Results Bacterial microcolonies were observed within the mucosa in 14 of 18 patients with CRS. In 10 of these patients colonies were positively identified as S. aureus. Staphylococcal microcolonies were observed at a lower level (1 of 8 patients) in normal sinus mucosa. There was no correlation between detection of S. aureus on the mucosal surface and microcolonization of the mucosa. Surprisingly, there was no evidence of an immune reaction to microcolonies. Indeed, fewer T lymphocytes (p = 0.03) and eosinophils (p = 0.03) were counted immediately surrounding the microcolonies compared with uninfected areas of the same tissue. Conclusion Bacterial microcolonies are prevalent within paranasal sinus mucosa and are commonly S. aureus. These microcolonies do not provoke immune detection and may represent a phenotype that actively evades host immunity. This may underpin the rcalcitrance of CRS to antibiotic therapy. These findings challenge classic views of both infection and mucosal immunity in human chronic disease. The presence of intramucosal bacteria in samples of normal sinus mucosa also questions the sensitivity of detecting nasal carriage of pathogens by swabbing the surface of the anterior nares.

A novel low temperature transcutaneous energy transfer system suitable for high power implantable medical devices: performance and validation in sheep.

Transcutaneous energy transfer (TET) systems use magnetic fields to transfer power across the skin without direct electrical connectivity. This offers the prospect of lifetime operation and overcomes risk of infection associated with wires passing through the skin. Previous attempts at this technology have not proved suitable due to poor efficiency, large size, or tissue damage. We have developed a novel approach utilizing frequency control that allows for wide tolerance in the alignment between internal and external coils for coupling variations of 10 to 20 mm, and relatively small size (50 mm diameter, 5 mm thickness). Using a sheep experimental model, the secondary coil was implanted under the skin in six sheep, and the system was operated to deliver a stable power output to a 15 W load continuously over 4 weeks. The maximum surface temperature of the secondary coil increased by a mean value of 3.4 +/- 0.4 degrees C (+/-SEM). The highest absolute mean temperature was 38.3 degrees C. The mean temperature rise 20 mm from the secondary coil was 0.8 +/- 0.1 degrees C. The efficiency of the system exceeded 80% across a wide range of coil orientations. Histological analysis revealed no evidence of tissue necrosis or damage after four weeks of operation. We conclude that this technology is able to offer robust transfer of power to implantable devices without excess heating causing tissue damage.

Are biofilms associated with an inflammatory response in chronic rhinosinusitis

Bacterial biofilms have been identified on the sinonasal mucosa of patients with chronic rhinosinusitis (CRS) but also on control samples. Their role in the disease pathogenesis is unproven. The objective of this study was to further evaluate the role of biofilms in CRS by assessing whether they are associated with an inflammatory response.

Stress-related changes to immune cells in the skin prior to wounding may impair subsequent healing

Higher psychological stress is associated with slower dermal wound healing, but the immunological mechanisms behind this effect are only partially understood. This paper aims to investigate whether immune cells present in the skin prior to wounding can affect subsequent healing in high-stress and low-stress participants. Two studies are presented in which skin biopsies were analysed using immunohistochemistry for numbers of macrophages and Langerhans cells, and immune cell activation (Study 2 only). Immune cells were related to perceived stress levels and subsequent healing. Study 1 included 19 healthy older adults and showed that higher stress was associated with significantly fewer macrophages in the skin. Study 2 included 22 younger adults and showed that higher stress was associated with significantly lower activation of immune cells in the skin. Furthermore, lower activation of immune cells (as measured by human leukocyte antigen (HLA expression)) and fewer Langerhans cells were associated with slower healing. Together these studies show the first preliminary evidence that the number and activation of immune cells in the skin prior to wounding are affected by stress and can impact healing. Larger studies are needed to confirm these effects.

Bacterial microcolonies exist within the sphenoid bone in chronic rhinosinusitis and healthy controls.

Some patients with chronic rhinosinusitis (CRS) exhibit thickening of the sinus bones that has been termed osteitis. The histopathology and microbiology of these changes have not been fully described. The aim of this study was to look for the presence of bacteria and immune cells within samples of bone from patients with and without CRS and correlate these findings to radiological findings.

Advanced imaging assessment of gout: comparison of dual-energy CT and MRI with anatomical pathology

Dual-energy CT (DECT) and MRI are advanced imaging methods used to visualise gout pathology. DECT can identify monosodium urate (MSU) crystals in people with gout,1 ,2 and also has conventional CT properties, allowing assessment of tophus and bone pathology.3 ,4 MRI is used to assess inflammation, bone erosion and cartilage damage in gout.5–7 This study aimed to compare DECT and MRI with corresponding anatomical pathology in the assessment of gout. Cadaveric joint specimens were obtained from two donors; a donor aged 82 years with crystal-proven tophaceous gout and a control donor aged 89 years without gout (12 joints from each). All joints were scanned by DECT (SOMATOM Definition Flash, Siemens Medical, Erlangen, Germany) and MRI (3T MAGNETOM Skyra, Siemens Medical), and then processed for histology, including digital photography of sectioned digits (sagittal plane) for macroscopic analysis, and preparation of histology slides from each individual joint for microscopic analysis. Slides were stained with H&E or 1% toluidine blue. Collection and use of cadaveric tissue was in accordance with the New Zealand Human Tissue Act 2008. All images and histology data were systematically assessed for gout pathology by experienced readers who were blinded to diagnosis and each others scores. …

Augmentation with an ovine forestomach matrix scaffold improves histological outcomes of rotator cuff repair in a rat model.

BackgroundRotator cuff tears can cause significant pain and functional impairment. Without surgical repair, the rotator cuff has little healing potential, and following surgical repair, they are highly prone to re-rupture. Augmenting such repairs with a biomaterial scaffold has been suggested as a potential solution. Extracellular matrix (ECM)-based scaffolds are the most commonly used rotator cuff augments, although to date, reports on their success are variable. Here, we utilize pre-clinical in vitro and in vivo assays to assess the efficacy of a novel biomaterial scaffold, ovine forestomach extracellular matrix (OFM), in augmenting rotator cuff repair.MethodsOFM was assessed in vitro for primary tenocyte growth and adherence, and for immunogenicity using an assay of primary human dendritic cell activation. In vivo, using a murine model, supraspinatus tendon repairs were carried out in 34 animals. Augmentation with OFM was compared to sham surgery and unaugmented control. At 6- and 12-week time points, the repairs were analysed biomechanically for strength of repair and histologically for quality of healing.ResultsOFM supported tenocyte growth in vitro and did not cause an immunogenic response. Augmentation with OFM improved the quality of healing of the repaired tendon, with no evidence of excessive inflammatory response. However, there was no biomechanical advantage of augmentation.ConclusionsThe ideal rotator cuff tendon augment has not yet been identified or clinically implemented. ECM scaffolds offer a promising solution to a difficult clinical problem. Here, we have shown improved histological healing with OFM augmentation. Identifying materials that offset the poorer mechanical properties of the rotator cuff post-injury/repair and enhance organised tendon healing will be paramount to incorporating augmentation into surgical treatment of the rotator cuff.

Renal denervation in male rats with heart failure improves ventricular sympathetic nerve innervation and function

Heart failure is characterized by the loss of sympathetic innervation to the ventricles, contributing to impaired cardiac function and arrhythmogenesis. We hypothesized that renal denervation (RDx) would reverse this loss. Male Wistar rats underwent myocardial infarction (MI) or sham surgery and progressed into heart failure for 4 wk before receiving bilateral RDx or sham RDx. After additional 3 wk, left ventricular (LV) function was assessed, and ventricular sympathetic nerve fiber density was determined via histology. Post-MI heart failure rats displayed significant reductions in ventricular sympathetic innervation and tissue norepinephrine content (nerve fiber density in the LV of MI+sham RDx hearts was 0.31 ± 0.05% vs. 1.00 ± 0.10% in sham MI+sham RDx group, P < 0.05), and RDx significantly increased ventricular sympathetic innervation (0.76 ± 0.14%, P < 0.05) and tissue norepinephrine content. MI was associated with an increase in fibrosis of the noninfarcted ventricular myocardium, which was attenuated by RDx. RDx improved LV ejection fraction and end-systolic and -diastolic areas when compared with pre-RDx levels. This is the first study to show an interaction between renal nerve activity and cardiac sympathetic nerve innervation in heart failure. Our findings show denervating the renal nerves improves cardiac sympathetic innervation and function in the post-MI failing heart.

Local Application of Lactoferrin Promotes Bone Regeneration In a Rat Critical‐Sized Calvarial Defect Model As Demonstrated by Micro‐CT And Histological Analysis

Lactoferrin is a multifunctional glycoprotein with therapeutic potential for bone tissue engineering. The aim of this study was to assess the efficacy of local application of lactoferrin on bone regeneration. Five‐millimetre critical‐sized defects were created over the right parietal bone in 64 Sprague–Dawley rats. The rats were randomized into four groups: group 1 (n  =  20) had empty defects; group 2 (n  =  20) had defects grafted with collagen gels (3 mg/ml); group 3 (n  =  20) had defects grafted with collagen gels impregnated with bovine lactoferrin (10 μg/gel); and group 4 (n  =  4) had sham surgeries (skin and periosteal incisions only). The rats were sacrificed at 4 or 12 weeks post‐operatively, and the calvaria were excised and evaluated with micro‐CT (Skyscan 1172) followed by histology. The bone volume fraction (BV/TV) was higher in lactoferrin‐treated animals at both timepoints, with groups 1, 2, 3 and 4 measuring 10.5  ±  1.1%, 8.6  ±  1.4%, 16.5  ±  0.6% and 24.27  ±  2.6%, respectively, at 4 weeks (P  <  0.05); and 12.2  ±  1.3%, 13.6  ±  1.5%, 21.9  ±  1.2% and 29.3  ±  0.8%, respectively, at 12 weeks (P  <  0.05). Histological analysis revealed that the newly formed bone within the calvarial defects of all groups was a mixture of woven and lamellar bone, with more bone in the group treated with lactoferrin at both timepoints. Our study demonstrated that local application of lactoferrin significantly increased bone regeneration in a rat critical‐sized calvarial defect model. The profound effect of lactoferrin on bone regeneration has therapeutic potential to improve the poor clinical outcomes associated with bony non‐union. LF In Vivo JTERM Authors Contributions. Copyright

Development of organic solvent-free micro-/nano-porous polymer scaffolds for musculoskeletal regeneration

The use of biomaterial scaffolds has been an enormous field of research in tissue engineering, where the aim is to use graft materials for assisting the human body in recovering lost functions. Currently, there are many ways biomaterial scaffolds can be fabricated; however, many of these techniques involve the use of toxic organic solvents during the process. As biocompatibility is one of the mandatory requirements in designing a successful scaffold, there is an interest in fabricating scaffolds that are completely organic solvent-free. This paper describes the development and characterization of novel micro-/nano-fibrillar composites (MFC/NFC) that can produce scaffolds which are completely free from organic solvents. In this research, the cytocompatibility of these materials have been tested in vitro using mouse osteoblast-like cells and primary rat tenocytes, where cell numbers increase over the culture period, demonstrating the material viability. Gene expression analysis of primary rat tenocytes on MFC/NFC scaffolds demonstrate tenocytic behavior, and histology studies show an increase in cell formation on NFC scaffolds. This study establishes the potential of using the MFC/NFC technique to produce completely organic solvent-free scaffolds capable of hosting musculoskeletal cells, in the hope of providing a graft material for non-union skeletal fractures and rotator cuff repairs.