Is there a fast track ("Darmstrasse") for fluids in the small intestine? Evidence from magnetic resonance imaging

BACKGROUND

The transit and distribution pattern of fluids in the small intestine is a key parameter for the dissolution and absorption of drugs. Although some information is known about the small intestinal water content after administration of fluid volumes and meals, the intestinal transit of orally ingested fluids and solutions has been barely investigated. The aim of this three-arm, cross-over, 9-subject human study was to investigate the transit of orally ingested water in the small intestine under fasting and postprandial conditions using MRI. To identify the ingested water, manganese gluconate, which can be identified with T1-weighted MRI sequences, was added as a marker. Using Horos (DICOM software), quantification of the distribution of Mn2+ ions in the gastrointestinal tract in fasted versus fed state (standard meal by FDA guidance and a light meal) was possible. The distribution and approximate wetted intestinal length was very similar in the fasting and postprandial states, suggesting rapid transport of water ingested after a meal through the chyme-filled small intestine in continuation of the "Magenstrasse" (stomach road). In some subjects, manganese gluconate reached deeper parts of the small intestine even more quickly in the postprandial state than in the fasting arm of the study. A deeper understanding of the behaviour of solutes in the gastrointestinal tract is fundamental to a mechanistic explanation for the kinetic interaction between food and drug intake (food effects).

George Sclavunos (1869-1954): Anatomical Insights and His Contribution into the "Magenstrasse of Waldeyer"

The purpose of this article is to present a well-known physician and highlight his contribution into an essential, but neglected anatomical feature. George Sclavunos (1869-1954) was a 20th century Greek physician, whose scientific work was a significant milestone in global medical knowledge. In 1899 he became Professor of Anatomy and Head Director of the Department of Anatomy. In 1906 Sclavunos G. published the first volume of the three volume book "Human Anatomy" (1906-1926), which is characterized by its unparalleled illustrations. For more than a century it was the most important book of medical literature in Greece. In 1926 he became a Full Member of the Academy of Athens and was named Life Partner of the International Anatomical Society. His interests included Anatomy, Physiology, Histology, as well as Osteology and Syndesmology. In his book "Human Anatomy", he described for first time the "Sialine Groove of the Stomach", which was described by Waldeyer-Hartz almost at the same time as the "Magenstrasse", a German word that means "stomach road". It is a ribbon-like path that extends along the lesser curvature of the stomach from the gastric cardia to the antrum and releases the gastric content directly into the small intestine. Its importance is confirmed by its association not only with drug delivery, but also with anti-obesity surgical techniques. The old German term has come back into common medical usage in view of the commonly performed Magenstrasse and Mill procedure, a form of bariatric surgery. CONCLUSION: Sclavunos G. managed to observe an anatomical structure that has remained of great importance until today.

Mixing and emptying of gastric contents in human-stomach: A numerical study

Stomach is one of the most important organs in human gastro-track. To better understand the operation of human-stomach, the process of mixing and emptying of gastric contents is simulated using a numerical method. The numerical results confirm that a fast pathway is located close to the lesser curvature of the stomach when water is emptied. However, this fast pathway doesn't exist when the gastric contents are composed of water and food boluses with different properties. The muscle contractions enhance the mixing of light food boluses and water, while they have limited effects on heavy food boluses. As a result, the foods are distributed in layers; heavy food boluses are located in the bottom layer. Besides the gastric motility and high viscosity of foods, the food matrix made of heavy food particles is also important to the formation of the Magenstrasse (stomach road). The food matrix and the zone of wrinkles behave like a porous medium which has higher flow resistance to the light food particles than to the water, leading to faster emptying of water. The water is emptied along the stomach wall since the flow resistance in the stomach wrinkles is smaller than the one in the food matrix. This mechanism is supported by the numerical results, while it might interpret the phenomena observed in the experiments.