A Case of Bilateral Pneumothorax With COVID-19 Infection.

Bilateral spontaneous pneumothorax is a serious complication of coronavirus disease 2019 (COVID-19). The incidence of any spontaneous pneumothorax in patients with the aforementioned viral infection when hospitalized is about 1%. Treatment can involve management such as oxygen support, tube thoracostomy, pleurodesis, or even invasive surgery. The associated mortality with this complication is about 33% to 52%. We present a case of bilateral pneumothorax in a patient diagnosed with COVID-19 without any history of smoking or underlying lung disease. Careful vigilance and close monitoring of this serious complication are mandatory in inpatients.

Radiographic changes of chronic recurrent multifocal osteomyelitis that persisted into adulthood.

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare non-infectious autoinflammatory disorder typically seen in young women. We describe the case of a young man who presented at 13 years of age with pain in the tibia, humerus, clavicle and hip. Worsening of the condition through clinical presentation and radiographic imaging was observed over 10 years. Radiographic imaging initially showed some sclerotic changes, but worsened to osteolytic lesions of the proximal tibia, elevation of the lateral cortex and thickening of the anterior cortex. Bone biopsy of his right anterior proximal tibia showed no infection or neoplasia. But, laboratory results showed elevation of inflammatory markers such as erythrocyte sedimentation rate or C-reactive protein. The patient was diagnosed with CRMO and treated with antibiotics for suspicion of chronic bacterial osteomyelitis. Chronic bone pain, abnormal imaging and elevation of inflammatory markers suggesting that chronic bacterial osteomyelitis can lead to difficulties with the diagnosis of CRMO.

A novel immune competent murine hypertrophic scar contracture model: a tool to elucidate disease mechanism and develop new therapies.

Hypertrophic scar (HSc) contraction following burn injury causes contractures. Contractures are painful and disfiguring. Current therapies are marginally effective. To study pathogenesis and develop new therapies, a murine model is needed. We have created a validated immune-competent murine HSc model. A third-degree burn was created on dorsum of C57BL/6 mice. Three days postburn, tissue was excised and grafted with ear skin. Graft contraction was analyzed and tissue harvested on different time points. Outcomes were compared with human condition to validate the model. To confirm graft survival, green fluorescent protein (GFP) mice were used, and histologic analysis was performed to differentiate between ear and back skin. Role of panniculus carnosus in contraction was analyzed. Cellularity was assessed with 4',6-diamidino-2-phenylindole. Collagen maturation was assessed with Picro-sirius red. Mast cells were stained with Toluidine blue. Macrophages were detected with F4/80 immune. Vascularity was assessed with CD31 immune. RNA for contractile proteins was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Elastic moduli of skin and scar tissue were analyzed using a microstrain analyzer. Grafts contracted to ∼45% of their original size by day 14 and maintained their size. Grafting of GFP mouse skin onto wild-type mice, and analysis of dermal thickness and hair follicle density, confirmed graft survival. Interestingly, hair follicles disappeared after grafting and regenerated in ear skin configuration by day 30. Radiological analysis revealed that panniculus carnosus doesn't contribute to contraction. Microscopic analyses showed that grafts show increase in cellularity. Granulation tissue formed after day 3. Collagen analysis revealed increases in collagen maturation over time. CD31 stain revealed increased vascularity. Macrophages and mast cells were increased. qRT-PCR showed up-regulation of transforming growth factor beta, alpha smooth muscle actin, and rho-associated protein kinase 2 in HSc. Tensile testing revealed that human skin and scar tissues are tougher than mouse skin and scar tissues.

Wound contraction is attenuated by fasudil inhibition of Rho-associated kinase.

BACKGROUND: Dermal scarring and scar contracture result in restriction of movement. There are no effective drugs to prevent scarring. RhoA and Rho-associated kinase have emerged as regulators of fibrosis and contracture. Fasudil, a Rho-associated kinase inhibitor, has been demonstrated to have antifibrotic effects in models of liver, renal, and cardiac fibrosis. The role of fasudil in preventing dermal scarring and contractures has not been studied. The authors used a rat model of dermal wound healing to assess the effects of fasudil with regard to the prevention of scarring. METHODS: Human scar tissue and surrounding normal skin were immunostained for RhoA and Rho-associated kinase. Full-thickness wounds were created on Wistar-Han rats, and fasudil (30 mg/kg/day) or saline was continuously delivered subcutaneously. Wound contraction was measured by gravitational planimetry. After 21 days, tissue was harvested for Masson's trichrome, hematoxylin and eosin, Ki-67, and CD31 staining. Fibroblast-populated collagen lattices were used to assess the mechanistic effects of fasudil on contractility. Myofibroblast formation was assessed in the presence of fasudil. RESULTS: Human scar tissue in the remodeling phase of repair showed increased expression of RhoA and Rho-associated kinase in scar tissue compared with surrounding normal tissue. Fasudil inhibited wound contraction as compared with controls. Hematoxylin and eosin and Masson's trichrome were similar between groups. Fasudil did not alter angiogenesis or proliferation. Fasudil inhibited fibroblast contractility and myofibroblast formation in vitro. CONCLUSIONS: There is growing evidence that the RhoA/Rho-associated kinase pathway plays an important role in wound healing and scar contracture. The authors present data showing that inhibition of Rho-associated kinase hinders fibroblast contractility and may be beneficial in preventing scar contracture.

Angiotensin-II mediates nonmuscle myosin II activation and expression and contributes to human keloid disease progression.

Aberrant fibroblast migration in response to fibrogenic peptides plays a significant role in keloid pathogenesis. Angiotensin II (Ang II) is an octapeptide hormone recently implicated as a mediator of organ fibrosis and cutaneous repair. Ang II promotes cell migration but its role in keloid fibroblast phenotypic behavior has not been studied. We investigated Ang II signaling in keloid fibroblast behavior as a potential mechanism of disease. Primary human keloid fibroblasts were stimulated to migrate in the presence of Ang II and Ang II receptor 1 (AT1), Ang II receptor 2 (AT2) or nonmuscle myosin II (NMM II) antagonists. Keloid and the surrounding normal dermis were immunostained for NMM IIA, NMM IIB, AT2 and AT1 expression. Primary human keloid fibroblasts were stimulated to migrate with Ang II and the increased migration was inhibited by the AT1 antagonist EMD66684, but not the AT2 antagonist PD123319. Inhibition of the promigratory motor protein NMM II by addition of the specific NMM II antagonist blebbistatin inhibited Ang II-stimulated migration. Ang II stimulation of NMM II protein expression was prevented by AT1 blockade but not by AT2 antagonists. Immunostaining demonstrated increased NMM IIA, NMM IIB and AT1 expression in keloid fibroblasts compared with scant staining in normal surrounding dermis. AT2 immunostaining was absent in keloid and normal human dermal fibroblasts. These results indicate that Ang II mediates keloid fibroblast migration and possibly pathogenesis through AT1 activation and upregulation of NMM II.

Calcium-dependent signaling in Dupuytren's disease.

BACKGROUND: Previous studies suggest that Dupuytren's disease is caused by fibroblast and myofibroblast contractility. Cell contractility in smooth muscle cells is caused by calcium-dependent and calcium-independent signaling mechanisms. In the calcium-dependent pathway, calcium/calmodulin activates myosin light chain kinase (MLCK). In this study, the effects of calcium/calmodulin inhibition with the FDA-approved drug fluphenazine on Dupuytren's fibroblast contractility and MLCK expression were tested. METHODS: Fibroblast lines from the palmar fascia of patients with Dupuytren's disease were explanted and used for in vitro study. The effect of fluphenazine on Dupuytren's fibroblast migration was determined using a scratch migration assay, and contractility was determined using fibroblast-populated collagen lattice (FPCL) assays. Immunohistochemical staining of MLCK in different samples of Dupuytren's tissue and normal fascia were compared. RESULTS: Fluphenazine demonstrated a dose-dependent inhibition of Dupuytren's fibroblast migration, with the maximum inhibition of migration observed at 20 µM (69.8 ± 1.9%). Fluphenazine also inhibited FPCL contraction in a dose-dependent manner. Maximal inhibition was observed at a fluphenazine concentration of 20 µM (52.5 ± 6.1%). Immunohistological staining illustrated that MLCK was predominantly expressed throughout the cytoplasm of select fibroblasts within Dupuytren's nodules, yet was absent in the fibroblasts of Dupuytren's cords and normal palmar fascia. CONCLUSIONS: Fluphenazine inhibits Dupuytren's fibroblast contractility and migration through inhibition of MLCK in vitro. However, the inconsistent expression of MLCK throughout Dupuytren's tissue suggests that calcium-dependent signaling may not be a primary mode of contracture formation. Fluphenazine inhibition of MLCK is not likely to be a target for the treatment of Dupuytren's disease.

Spatially inhomogeneous enhancement of fluorescence by a monolayer of silver nanoparticles.

Near-field scanning optical microscopy (NSOM) was applied to study the effect of a two-dimensional array of silver nanoparticles on the spatial distribution and magnitude of fluorescence signal enhancement for a monolayer of Rhodamine 6G (Rh6G). Twenty polyelectrolyte monolayers were deposited between the nanoparticles and the dye by a layer-by-layer deposition technique resulting in a 15-20 nm separation cushion, necessary to minimize the fluorescence signal quenching. The fluorescence signal in NSOM images was found to be distributed inhomogeneously as small (100-200 nm in diameter) fluorescent clusters with typically 5-30 times higher fluorescence intensities than a sample without nanoparticles. The position and relative intensity of the clusters was found to be dependent on the excitation wavelength, suggesting that the enhancement originates from the nanoparticle surface plasmon resonance.