Innervation of submucosal adipocytes in the human colon

The submucosal plexus regulates various activities of the gastrointestinal mucosa. As the submucosa in the human colon contains adipose tissue we hypothesized that submucosal neurons might also innervate this tissue. We stained submucosal nerves for the enzyme NADPH-diaphorase, which is a marker for nitric oxide synthase-containing nerves. This resulted in the staining of neurons in submucosal ganglia and numerous nerve fibers throughout the submucosa. These fibers were found to be in close contact with adipocytes, and in many cases fine nerve fibers displaying varicosities were found on the surface of these cells. At least some of these fibers originated from submucosal neurons. In addition, cell bodies of submucosal neurons were in close proximity to adipocytes. It is concluded that submucosal nerves innervate adipose tissue in the submucosa, which is a novel role for these nerves, and might have important functional implications.     

A cumulative shear mechanism for tissue damage initiation in shock-wave lithotripsy

Evidence suggests that inertial cavitation plays an important role in the renal injury incurred during shock-wave lithotripsy. However, it is unclear how tissue damage is initiated, and significant injury typically occurs only after a sufficient dose of shock waves. Although it has been suggested that shock-induced shearing might initiate injury, estimates indicate that individual shocks do not produce sufficient shear to do so. In this paper, we hypothesize that the cumulative shear of the many shocks is damaging. This mechanism depends on whether there is sufficient time between shocks for tissue to relax to its unstrained state. We investigate the mechanism with a physics-based simulation model, wherein the basement membranes that define the tubules and vessels in the inner medulla are represented as elastic shells surrounded by viscous fluid. Material properties are estimated from in-vitro tests of renal basement membranes and documented mechanical properties of cells and extracellular gels. Estimates for the net shear deformation from a typical lithotripter shock (approximately 0.1%) are found from a separate dynamic shock simulation. The results suggest that the larger interstitial volume (approximately 40%) near the papilla tip gives the tissue there a relaxation time comparable to clinical shock delivery rates (approximately 1 Hz), thus allowing shear to accumulate. Away from the papilla tip, where the interstitial volume is smaller (approximately 20%), the model tissue relaxes completely before the next shock would be delivered. Implications of the model are that slower delivery rates and broader focal zones should both decrease injury, consistent with some recent observations.     

Neutropenic typhlitis

Neutropenic typhlitis is an acute inflammation of the cecum occurring in neutropenic patients. Two cases are described, both presenting typical features of the disease. It is our experience that the treatment approach should consist of bowel rest, fluid therapy, and massive administration of broad spectrum antibiotics. In some cases, full recovery will follow. If abdominal signs persist, surgery should be deferred until hematologic convalescence occurs. At this time, cecostomy and drainage should be adequate. Only in very severe cases, with wide-spread necrosis, should a right hemicolectomy be performed.     

Identification of a proline-binding motif regulating CD2-triggered T lymphocyte activation

An intracellular protein termed CD2 binding protein 2 (CD2BP2), which binds to a site containing two PPPGHR segments within the cytoplasmic region of CD2, was identified. Mutagenesis and NMR analysis demonstrated that the CD2 binding region of CD2BP2 includes a 17-aa motif (GPY[orF]xxxxM[orV]xxWxxx GYF), also found in several yeast and Caenorhabditis elegans proteins of unknown function. In Jurkat T cells, over-expression of the isolated CD2BP2 domain binding to CD2 enhances the production of interleukin 2 on crosslinking of CD2 but not the T cell receptor. Hence, a proline-binding module distinct from SH3 and WW domains regulates protein–protein interactions.