What neurons hide behind calretinin immunoreactivity in the human gut?

Calretinin (CALR) is often used as an immunohistochemical marker for the histopathological diagnosis of human intestinal neuropathies. However, little is known about its distribution pattern with respect to specific human enteric neuron types. Prior studies revealed CALR in both myenteric and submucosal neurons, most of which colabel with choline acetyl transferase (ChAT). Here, we specified the chemical code of CALR-positive neurons in small and large intestinal wholemounts in a series of 28 patients. Besides other markers, we evaluated the labeling pattern of CALR in combination with vasoactive intestinal peptide (VIP). In colonic submucosa, CALR and VIP were almost completely colocalized in about three-quarters of all submucosal neurons. In the small intestinal submucosa, both the colocalization rate of CALR and VIP as well as the proportion of these neurons were lower (about one-third). In the myenteric plexus of both small intestine and colon, CALR amounted to 11 and 10 %, respectively, whereas VIP to 5 and 4 % of the whole neuron population, respectively. Colocalization of both markers was found in only 2 and 3 % of myenteric neurons, respectively. In section specimens, nerve fibers coreactive for CALR and VIP were found in the mucosa but not in the muscle coat. Summarizing the present and earlier results, CALR was found in at least one submucosal and two myenteric neuron populations. Submucosal CALR+/VIP+/ChAT± neurons innervate mucosal structures. Furthermore, CALR immunoreactivity in the myenteric plexus was observed in morphological type II (supposed primary afferent) and spiny type I (supposed inter- or motor-) neurons.

[Injuries of the knee extensor complex in children]. / Verletzungen des Kniestreckapparates im Wachstumsalter.

BACKGROUND: Fractures of the knee extensor complex are relatively rare injuries in children. We distinguish between a pure tendon rupture and ruptures with bony avulsions. A mid-substance tear in children is a relatively rare injury, whereas bony avulsions due to skeletal immaturity are seen more often. Sole bony fractures of the patella also only account for a low number of paediatric related fractures. Sleeve fractures are characterized by an avulsion of cartilage and, usually, bone pulled off from the distal patella pole. Avulsion fractures of the tibia tubercle are found in the group of sportive adolescents. TREATMENT: Especially dislocated fractures should be conveyed to surgical therapy to avoid excessive bone callus. Timely diagnostics and an efficient and consistent treatment are recommended. Deformities and dislocated avulsions will regularly not remodel spontaneously during further growth. Therefore, it is mandatory to reconstruct the articular surface and the knee extensor complex to avoid future complications such as osteoarthritis or elongation of the knee extensors.