RESUMEN
We present a case of a 60-year-old male with known seropositive rheumatoid arthritis and cerebral vasculitis who presented to the emergency room with abrupt onset lower back and abdominal pain. The patient developed peritonitis which led to an abdominal laparotomy where jejunal ischemia, necrosis, and perforation were found, requiring bowel resection. On pathology examination, the patient had mesenteric vessel intramural inflammation indicative of vasculitis. He developed an anastomotic leak on postoperative Day 4 and elected hospice care. A high index of suspicion for mesenteric vasculitis should be considered in patients presenting with abdominal pain in the setting of known rheumatoid arthritis associated vasculitis, especially patients with long-standing rheumatoid arthritis. The high mortality represented by gastrointestinal involvement in rheumatoid arthritis associated vasculitis warrants investigation in high-risk patients, despite its low prevalence. Treatment may consist of high-dose corticosteroids, immunosuppressive agents, biologic therapies that target the underlying autoimmune process, and in severe cases, bowel resection.
RESUMEN
We demonstrate that fused silica capillaries are suitable for single molecule fluorescence resonance energy transfer (smFRET) measurements at high pressure with an optical quality comparable to the measurement on microscope coverslips. Therefore, we optimized the imaging conditions in a standard square fused silica capillary with an adapted arrangement and evaluated the performance by imaging the focal volume, fluorescence correlation spectroscopy benchmarks, and FRET measurements. We demonstrate single molecule FRET measurements of cold shock protein A unfolding at a pressure up to 2000 bars and show that the unfolded state exhibits an expansion almost independent of pressure.