Stefan Holland-Cunz

Diametaphyseal forearm fractures are difficult to treat because standard methods for long-bone fracture stabilization in the metaphyseal or diaphyseal regions are less effective in this transition zone. We hypothesized that there is no difference in outcomes between conservative and surgical treatment of diametaphyseal forearm fractures. This retrospective analysis included 132 patients who had undergone treatment for diametaphyseal forearm fracture between 2013 and 2020 at our institution. The primary analysis compared complications occurring in patients treated conservatively with those occurring in patients managed surgically (ESIN, K-wire fixation, KESIN stabilization, or open reduction and plate osteosynthesis). In a subgroup analysis, we compared the two most frequently applied surgical stabilization techniques in distal forearm fractures (i.e., ESIN and K-wire) with conservative treatment. The mean age of the patients at the time of intervention was 9.43 ± 3.78 years (mean ± SD). Most patients were male (91; 68.9%), and 70 of 132 (53.1%) patients underwent surgical stabilization. The rate of re-intervention or complications was similar after conservative and surgical treatment, and ESIN or K-wire fixation achieved comparable complication rates. Recurrent displacement of fragments was the most frequent reason for re-interventions (13 of 15 patients; 86.6%). There was no permanent damage as a result of a complication. The median time of exposure to image intensifier radiation was comparable between ESIN (95.5 s) and K-wire fixation (85.0 s), but significantly lower during conservative treatment (15.0 s; p = 0.001).

Aquaporin 1 (AQP1) is one of thirteen known mammalian aquaporins. Its main function is the transport of water across cell membranes. Lately, a role of AQP has been attributed to other physiological and pathological functions including cell migration and peripheral pain perception. AQP1 has been found in several parts of the enteric nervous system, e.g., in the rat ileum and in the ovine duodenum. Its function in the intestine appears to be multifaceted and is still not completely understood. The aim of the study was to analyze the distribution and localization of AQP1 in the entire intestinal tract of mice. AQP1 expression was correlated with the hypoxic expression profile of the various intestinal segments, intestinal wall thickness and edema, as well as other aspects of colon function including the ability of mice to concentrate stools and their microbiome composition. AQP1 was found in a specific pattern in the serosa, the mucosa, and the enteric nervous system throughout the gastrointestinal tract. The highest amount of AQP1 in the gastrointestinal tract was found in the small intestine. AQP1 expression correlated with the expression profiles of hypoxia-dependent proteins such as HIF-1α and PGK1. Loss of AQP1 through knockout of AQP1 in these mice led to a reduced amount of bacteroidetes and firmicutes but an increased amount of the rest of the phyla, especially deferribacteres, proteobacteria, and verrucomicrobia. Although AQP-KO mice retained gastrointestinal function, distinct changes regarding the anatomy of the intestinal wall including intestinal wall thickness and edema were observed. Loss of AQP1 might interfere with the ability of the mice to concentrate their stool and it is associated with a significantly different composition of the of the bacterial stool microbiome.