The role of the duodenojejunal junction in regulating the evacuatory function of the duodenum

Chronic experiment on dogs was performed to study the effect of duodenojejunal junction exclusion from the evacuatory process on dynamics of gastric and duodenal emptying of the carbohydrate and fatty food. It is established that in the case of exclusion of the duodenojejunal junction, the degree of coordination of gastric and duodenal emptying decreases, dynamics of chyme evacuation from the duodenum considerably changes. It is concluded that the duodenum is not a mere transporter of food coming from the stomach, but has its own regulation mechanisms represented by the duodenojejunal junction and the Treitz ligament.     

Characteristics of the motor function of the proximal segment of the gastrointestinal tract

Dynamics of the solid carbohydrate food evacuation from the duodenum has been determined in chronic experiments on dogs using modified technique for multiple drainage of intestinal fistulas. It is established that dynamics of the duodenal chyme emptying depends on the absolute quantity of the stomach-evacuated food and includes three phases: increase in the evacuation rate, exponential phase and that of accelerated evacuation. The highest rate of the duodenal contents is observed in the period from the 90th to 210th minute after food intake, the lowest one--at the end of the digestive cycle. A conclusion is made concerning the high degree of coordination of the evacuatory stomach and duodenum function.     

Variants of the suspensory muscle of the duodenum (Treitz's ligament) and the anatomical basis for its effective dissection in duodenal stasis

Depending on peculiarities of the duodenum fixation to the posterior abdominal wall, normal (normoduodenum), dolichoduodenum and duodenoptosis variants are distinguished. The m. suspensoris duodeni (ligament of Treits) in each variant has its peculiarities. At the normoduodenum and dolichoduodenum, the ligament of Treitz contains a considerable amount of striated muscle tissue. At the duodenoptosis--it consists of a loose fibrous connective tissue with single smooth (non-striated) muscle fibers. As demonstrate anatomical experiments for dissection of the normal ligament of Treitz and of its two variants, dissection of the ligament of Treitz at duodenoptosis eliminates essential anatomical prerequisites of duodenostasis.     

Investigation of development, structure and function of the phrenicocolic and duodenal suspensory ligaments

The development and structure of the duodenal suspensory ligament and the phrenicocolic ligament were studied in the human fetus, newborn and adult. The observations presented show that the superior retention band is transformed into the suspensory ligament of the duodenum. Within this ligament the muscle of Treitz develops. The inferior retention band atrophies. A new ligament, the phrenicocolic ligament, is formed in the fetal period of life. In this ligament, smooth muscle cells develop. The possible functions of the suspensory ligament of the duodenum and the phrenicocolic ligament are discussed.     

Regulation of gastric emptying

Studies carried out in the years since William Beaumont's direct observations of gastric motility have provided increased understanding of the physiological roles of the stomach and of the mechanisms for the regulation of gastric motility. Tonic contractions of the proximal stomach are of primary importance for transfer of liquids from the stomach to the duodenum. Peristaltic contractions of the distal stomach are of primary importance for reducing the size of solid food particles and for transfer of solids to the duodenum. Because gastric emptying requires a net antral-duodenal pressure gradient, contractions of the duodenum also influence the rate of gastric emptying. Gastrointestinal hormones, including gastrin, cholecystokinin, secretin, somatostatin, and others, are released by contact of chyme with the intestinal mucosa, and affect contractions of the proximal stomach, distal stomach, and duodenum. Neural reflexes that arise from the stomach act through autonomic motor nerves to allow regulation by the central nervous system of gastric motility. gamma-Aminobutyric acid, opioids, and bombesin may serve as central neurochemical regulators of gastric motility.     

The effect of food protein-induced intestinal anaphylaxis on rate of transit

The aim of this study was to determine if the altered jejunal motility previously demonstrated in this animal model of food protein-induced intestinal anaphylaxis is (a) a localized (the jejunal site of challenge), or a generalized response of the small intestine, and (b) associated with more rapid aboral transit of intraluminal contents. Hooded-Lister rats, 100-150 g in weight, were sensitized by intraperitoneal injection of 10 micrograms egg albumin. Control rats were sham-sensitized. On day 7 rats were surgically prepared with six bipolar electrodes from duodenum to ileum and (or) a jejunostomy tube was positioned at the ligament of Treitz. On day 14, after an 18-h fast, recording of myoelectric activity were obtained from four sensitized animals with electrodes from duodenum to ileum during a control period for 45 min after saline challenge and for 45 min after antigen challenge. Control (n = 25) and sensitized (n = 31) animals with only a jejunostomy had Na2 51CrO4 instilled through the jejunostomy in 0.5 mL of saline, with or without egg albumin, either during a fast or after a standard meal. Propulsion of isotope through the small bowel was allowed to progress for 15 min, the animals were sacrificed, and their gut was removed for division into eight equal segments of small intestine, cecum, and remaining colon. The radioactivity of each segment was determined in a gamma counter.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of sampling interval and temperature on the accuracy of food consumption estimates from stomach contents

The effect of temperature and sampling interval on the accuracy of food consumption estimates based on stomach contents was studied using simulation. Three temporal patterns of feeding were considered (scattered throughout the day, one 5 h period or two 5 h periods) and gastric evacuation was modelled according to published values. Sampling intervals of 3 h gave reasonable food consumption estimates (2 to 19% error) at all temperatures. Comparably, sampling intervals as large as 12 h gave reasonable estimates of food consumption (1 to 20% error) when temperature was set to ≤10° C. At temperatures <5° C, even 24 h intervals (equivalent to one daily sampling) provided reasonable estimates of daily food consumption (2 to 19% error) for all but the highest gastric evacuation rate combined with one daily feeding period (47% error). The temperature effect on estimation error resulted from diminishing temporal fluctuations in stomach contents with slower gastric evacuation rates. It follows that sampling effort may be considerably minimized when estimating food consumption from stomach contents during periods with low temperatures such as the winter time experienced by temperate fishes.     

Effect of experimental conditions on the stomach evacuation of Coregonus lavaretus L.

The gastric evacuation of juveniles of Coregonus lavaretus L. fed on living Daphnia pulicaria was investigated. Three successive stages of stomach evacuation were observed when one meal per day was given: (i) a lag phase between the end of food intake and the beginning of stomach evacuation, (ii) a linear reduction of stomach content, (iii) a long residence time for food relics in the stomach. The initial stomach content and the stomach evacuation time are correlated positively. The stomach content increased during feeding when three meals day ⁻¹ were provided and it decreased when no food was available. During the course of an experiment the highest stomach content found increased with increasing daly ration. Excess feeding resulted in a low stomach content similar to that found with rations about 30–50% of the maximum daily food intake. Therefore the daily food intake cannot be determined by the single parameter of stomach content alone. Identical initial stomach contents showed significantly higher stomach evacuation rates under three meals day⁻¹ conditions than under one meal day⁻¹ conditions.     

Influences of food particle size and dietary energy content on patterns of gastric evacuation in fish: test of a physiological model of gastric emptying

The evacuation of food from the stomach is probably not a continuous smooth process but may occur in a pulse-like (step-wise) fashion. It is hypothesised that the pattern of emptying is influenced by feedback signals from receptors located in the upper intestinal tract and by factors affecting the rate of physical/chemical breakdown of the food particles. Mathematical functions used for describing evacuation patterns imply that emptying is continuous and they are, therefore, at best, only approximations. It was predicted that different mathematical expressions would give best fit to empirical data from gastric evacuation studies dependent upon the experimental conditions employed. An analysis of published data supported the predictions and revealed that an exponential function best described the evacuation of small, easily digested prey items, but a linear expression gave the best fit to data of the emptying of large food items. It is suggested that differences in surface-to-volume ratios between large and small food particles and the friabilities of different food types are important in determining the pattern of emptying. Whilst dietary energy content also appears to be an important factor in the governing of gastric evacuation, it appears that emptying pattern in fish species is rather less sensitive to changes in dietary composition than is gastric emptying in mammals.     

Gastric evacuation in plaice, Pleuronectes platessa L.: effects of temperature and fish size

Using a volume dependent model of gastric evacuation, the effects of temperature and fish size were examined. Rates of gastric evacuation were unaffected by fish size but increased with increasing temperature. The relationship between maximum stomach volume and fish weight was found to be a linear one. From information of gastric evacuation rates and stomach volume, the amount of food evacuated from the stomach per day was calculated for different size classes of fish. Daily food evacuation increased in proportion to body weight to the power 0·68. Assuming these methods give a crude estimate of daily food intake, the results are discussed in relation to published work on food intake in fishes.     

Gastric evacuation of mixed stomach contents in predatory gadoids: an expanded application of the square root model to estimate food rations

A mechanistic gastric evacuation model of mixed stomach contents was established. Its simple generic nature should prove useful for studying predator‐prey interactions in fish communities. Only prey lengths were required as additional input. Surface dependent digestive processes were considered to act on equal fractions of individual prey‐cylinder surfaces. Primary and interactive effects of size, energy density and resistance to digestion of individual prey in a stomach were described by the model. Model predictions of results from experiments on gastric evacuation of meals composed of different prey types demonstrated the capability of this model, as opposed to previously applied model principles, to predict evacuation of mixed stomach contents involving the three above‐mentioned prey characteristics. The study furthermore illustrated that estimates of food ration might be severely biased by using improperly formulated effects of prey characters on gastric evacuation, and demonstrated that the new model holds the potential to predict food ration and diet composition for wild populations of predatory fishes.     

Secretory activity of the stomach during modeling of enhanced filling of abdominal veins

Determination of the secretory activity of the stomach and ultrasound scanning of human gastroduodenal organs and vessels in experiments with −12° and −15° head-down tilting (HDT) hypokinesia were performed. As a result of short-term (12–24 h) HDT hypokinesia with the minimized hypokinesia factor, parenchymatous organs enlarged, and the walls of hollow organs thickened. Enhanced blood filling of abdominal veins was accompanied by elevated pepsinogen levels in blood and urine and increased gastric contents in fasting subjects. The increased tonicity of the pylorus and the delayed evacuation of stomach contents indicated the activation of hydrochloric acid secretion. Simultaneously, the bile and pancreatic juice were secreted more profusely, and the intestinal contents in the duodenum increased. It has been shown that the modeled enhancement of blood filling of abdominal veins stimulates gastric secretion on an empty stomach, which is accompanied by activation of secretion in the liver and pancreas.     

Investigation of the evacuation function of the gastrointestinal tract during a five-day dry immersion

Six male volunteers for dry immersion (DI) simulating microgravity effects in the human body were subjects in the study on the evacuation function of the gastrointestinal tract (GIT). The investigation was aimed to evaluate liquid food evacuation from the stomach (the ¹³C-acetate test) and time of chymus orocecal transit (the H₂-inulin test). The ¹³C-acetate test did not reveal changes in stomach evacuation activity after 4 days in DI. The H₂-inulin test demonstrated shortening of the chymus’s transit along the small intestine and extension of chymus passage from the oleum to cecum. The subsequent reduction of inulin metabolism in the large intestine suggested inhibited passage of these GIT segments. The results showed that the stability of liquid evacuation from the stomach and acceleration of the chymus’s transit along the small intestine hinder evacuation of the large intestine content, which is the primary cause of the inhibition of the GIT evacuation activity during DI.     

A New Method of Intestinal Perfusion for the Management of Chronic Renal Failure: A Preliminary Report

Usefulness of intestinal perfusion in the treatment of uremia is limited by (a) low clearances, (b) atrophy of the perfused mucous membrane, and (c) poor toleration by the patient. A method of intestinal perfusion has been devised which uses most of the small bowel without exclusion from the fecal stream. Two Roux-en-Y anastomoses are made, the proximal 12″ below the ligament of Treitz, the distal 18″ above the ileocecal valve. Perfusion is carried out between the proximal jejunostomy and distal ileostomy, daily. Six litres of fluid are perfused in four hours. The bowel is used for digestion during the remaining 20 hours of the day. Patients have solid bowel movements daily, prior to perfusion. Reflux of intestinal contents, between perfusions, is slight. The method allows maximal diffusion, may prevent bowel atrophy and is well tolerated by the patient. The method is being used, in conjunction with hemodialysis, in treatment of chronic uremia.     

The effect of extragastric vagotomy on gastric emptying and motility of the small intestine

Selective parasympathetic denervation of small and some large intestine has been performed in dogs. Chronic experiment on these dogs has revealed that this operation: has no effect on frequency and amplitude of intestine contractions during the first phase of the digestive process but it is accompanied by significant relaxation of the motor intestine activity in the second phase, causes a retardation of the rate of evacuation from stomach by 56.0% in dogs subjected to extragastric vagotomy as well as pH of chyme in the duodenum by 1-1.5 units above the norm.     

Gastric control of duodenal electric activity--the function of the gastroduodenal junction.

An investigation was made into the links between electric activity of antral and of duodeno-jejunal musculature in different functional conditions. The function of the gastroduodenal junction in this linking mechanism was analysed. The following observations were made: (a) in the absence of gastric stimulation, the slow electric activities of stomach and duodenum appear to be completely independent; (b) the gastroduodenal junction evidences no electric activity of its own but is affected by that of the two adjacent structures; (c) chemical stimulation of the gastric mucosa causes activation of the electric and mechanical activity of the stomach and analogous activation of duodenal musculature; this effect is mediated by the gastroduodenal junction; (d) very probably, the transmission of gastric activation to the duodenum is myogenic for it ceases after surgical transection but not after cooling or after ligature. The possible functional role of the pyloric junction in the complex gastroduodenal mechanism is discussed.     

Hydrogen ion concentration in the gastrointestinal tract of channel catfish

Hydrogen ion concentrations (pH) of the digestive tracts of channel catfish were determined for fish of two sizes (892 and 134 g average weight) at two environmental temperatures (28 and 23°C). Acidic conditions (pH 2–4) were present in the stomach contents of all catfish with slightly higher pH values in stomachs of fish at 28°C. The pH increased to slightly alkaline values (pH 7–9) in the duodenum and reached a maximum level (pH 8.6) in the upper intestinal region and then decreased in the lower segments to approach neutrality in the colon. The pH of the bile ranged from 6.1 to 7.5 and was higher in fish maintained at 28°C. Higher environmental temperatures (28°C) resulted in a slightly lower pH throughout the intestinal and colon segments. The larger catfish had lower intestinal length/body weight ratios than smaller catfish. As the result of distension due to increased food consumption, catfish maintained at 28°C had shorter intestinal tracts than catfish maintained at 23°C.     

Daily ration of adult perch, Perca fluviatilis L. during summer in Loch Leven, Scotland

Adult perch, Perca fluviatilis L., were sampled at 3-hourly intervals throughout 24-h periods from June-September 1971, and in June and August 1972. The wet weight of each major food component from the stomachs was expressed in parts per 10 000 of the fresh weight of the fish. From samples at capture, and others taken from caged fish at known time-intervals after capture, the rate of stomach evacuation was estimated. Food consumption between netting times was calculated as the increment between successive initial values of stomach contents, plus the amount evacuated in the interval. As the evacuation rate of caged fish was slower than that of free fish the estimates of food turnover are minimal ones. The perch were consuming 6.5 % of their wet body weight per day in June, and this ration had decreased to 3.2% by September.     

Cytochemical localization of alkaline phosphatase in intestinal metaplasia of the human stomach

Summary Alkaline phosphatase in the brush border of areas of intestinal metaplasia of human stomach was studied cytochemically. All absorptive cells in the upper part of the villi of the duodenum had strong alkaline phosphatase activity but, in areas of intestinal metaplasia, the metaplastic glands consisted of alkaline phosphatase-positive and negative absorptive cells. Alkaline phosphatase activity was found in tall dense microvilli of absorptive cells in areas of intestinal metaplasia and in the duodenum. However, in some areas of metaplastic epithelium, the activity was very weak in some tall dense microvilli of absorptive cells but strong in those of neighbouring absorptive cells. No alkaline phosphatase activity was found in short sparse microvilli of absorptive cells in areas of intestinal metaplasia. The difference in alkaline phosphatase activity in microvilli of different cells in areas of intestinal metaplasia, which is not seen in the duodenum, indicates abnormal morphological and enzymatic differentiation in intestinal metaplasia.