Meal Volume Research Articles

639 THE EFFECTS OF FORMULA (F) COMPOSITION AND VOLUME ON GASTRIC EMPTYING PATTERNS (GEP) IN THE PRETERM INFANT (PI)

GEP may be influenced by the test meal volume (V) and its composition. To determine the effects of F composition and V on GEP, 4 PI, 1.3-1.7 kg, were fed consecutive alternate feedings of Similac 24 (S) or LBW (L) at 20 ml/kg using polyethylene glycol (PEG), a non-toxic, non-absorbable marker. Studies were repeated weekly for 3 wks. Four other PI, 1.1-1.8 kg, were fed S at consecutive alternate V of 10 or 30 ml/kg. All feedings were delivered by nasogastric tube over a 5-min period, 3 hrs apart, with the PI in the supine position. 1 ml of PEG was added to each ml of F. 1-ml gastric aspirates were obtained at 10-min intervals for 1 hr and replaced with equal V of F containing 4 mg PEG per ml F. Gastric residual volumes (GRV) were calculated from equations for double sampling. In PI fed 20 ml/kg, the mean GRV at 10 min was 35% for S and 46% for L, and neither changed significantly thereafter. There was no significant difference in the mean GRV between PI fed 20 ml/kg S or L during the test period. In PI fed S, 10 ml/kg, the mean GRV was 52% at 10 min and did not change significantly over the next 50 min. In PI fed 30 ml/kg, the mean GRV was 32% at 30 min and did not change significantly thereafter. Except at 20 min, the mean GRV was significantly greater at all intervals in the PI fed 10 ml/kg compared to 30 ml/kg. Conclusions: In the healthy PI, 1) there is no significant difference in GEP during the first hr after feeding in PI fed equal volumes of S or L; 2) the mean GRV varies with the volume of F fed.

Meal occurrence in Japanese quail in relation to particle size and nutrient density

Japanese quail ate shorter meals with pellets than with mash, and longer and more frequent meals with diluted mash (40% cellulose) than undiluted mash. The differences with particle size were due to different rates of ingestion, and those with nutrient density to different meal volumes and different rates of passage. Average meal size was about the same with all foods in terms of weight eaten, but not nutrients digested. Short-term adjustments in feeding were concerned mainly with changes in meal frequency, and longer-term adjustments mainly with changes in meal size. It is concluded that the control of meal-eating is concerned with emptying and filling of the digestive tract and not with changing levels of circulating nutrients, and parts of the gut that may be involved are suggested.

Rate of digestion of 51Cr-hemoglobin by Stomoxys calcitrans (Diptera: Muscidae).

Bovine hemoglobin labeled with 51Cr was used to follow the digestion of the blood meal in Stomoxys calcitrans and to determine the rate of digestion of 51Cr-labeled hemoglobin and the excretion of free 51Cr. Digestion of the labeled hemoglobin by untreated flies fed only fresh, labeled, heparinized bovine blood began within the first hour postfeeding and was completed within 48 h: digestion did not begin in treated flies (flies fed soybean trypsin inhibitor with the blood) for ca 24 h. After 24 h, the rate of digestion in control and treated flies was the same. Excretion of free 51Cr began at about 4 h in control flies and at 24 h in treated flies. Labeling with chromium can be used to follow digestion in vivo and is also useful in determining the volume of blood meals.

Factors Influencing Gastric Emptying

Gastric emptying time may be of investigative value and evidentiary significance in estimating the time of death. However, in order to express an expert opinion with a degree of certainty, the time, volume, and character of the last meal must be known, and other factors considered. The maximum normal emptying time for the healthy intact stomach is 6 h. Factors accelerating or delaying gastric emptying include fear and apprehension, acute and chronic diseases, trauma, drugs, and the stomach that has undergone surgery. Recognition of these influences supports the conclusions that the forensic pathologist draws regarding the interval between the last meal and death.

Relative role of pyloroplasty size, truncal vagotomy, and milk meal volume in canine gastric emptying.

The gastric emptying of 10, 20, or 40 ml/kg body mass milk meals was measured before and after Heineke-Mikulicz pyloroplasty of 3, 5, or 7 cm (6 dogs) or truncal vagotomy (3 dogs). The pyloroplasty group then underwent vagotomy, following which the tests were repeated. Initial gastric emptying (in the first 10 min) was increased after 5-and 7-cm pyloroplasties (P<0.01) and particularly after vagotomy with all sizes of pyloroplasty (P=0.001). Regardless of the volume of meal used, after vagotomy and pyloroplasty there was a 51–63% decrease in intragastric volume within the first 10 min. Increased duodenogastric reflux occurred in those dogs who showed rapid initial gastric emptying. After the first 10 min all groups were shown to have virtually normal gastric emptying, except the truncal vagotomy group in which gastric emptying was delayed (P<0.05). It is the combination of pyloroplasty with vagotomy which is required to produce the very rapid initial gastric emptying of a liquid meal following vagotomy with pyloroplasty. It is concluded that two mechanisms control the gastric emptying of a milk meal. The first acts quickly, is dependent on an intact pylorus, and is influenced by the intragastric volume; the second is a more slowly acting mechanism, requiring up to 10 min to have its effect, and is not dependent on an intact pylorus or the intragastric volume. After vagotomy and pyloroplasty, the speed of gastric emptying in the first 10 min is proportional to the original meal volume, and therefore the therapy of postvagotomy diarrhea and dumping with small frequent meals seems rational.

Models of gastric emptying.

Some empirical and theoretical models of the emptying behaviour of the stomach are presented. The laws of Laplace, Hooke, and Poisseuille are used to derive a new model of gastric emptying. Published data on humans are used to test the model and evaluate empirical constants. It is shown that for meals with an initial volume of larger than or equal to 300 ml, the reciprocal of the cube root of the volume of meal remaining is proportional to the time the meal is in the stomach. For meals of initial volume of less than 300 ml the equation has to be corrected for the fact that the 'resting volume' of gastric contents is about 28 ml. The more exact formula is given in the text. As this model invokes no neural or hormonal factors, it is suggested that the gastric emptying response to the volume of a meal does not depend on these factors. The gastric emptying response to the composition of the meal does depend on such factors and a recent model of this process is used to evaluate an empirical constant.

Effects of hydrochlorides of amino acids in test meals on gastric emptying.

Four subjects were given test meals containing various concentrations of hydrochlorides of glycine, alanine, arginine, phenylalanine and tryptophan. The gastric contents were recovered after 20 min. The volume of the original meal recovered was assessed from the amount of marker substance aspirated. It was found that the slowing of gastric emptying of amino acid hydrochlorides was consistent with their action as weak acids. However, tryptophan and phenylalanine were slightly more effective than was predicted on the basis of their actions as acids.

Effect of Highly Selective Vagotomy on Gastric Emptying

Our objective was to study the gastric motility after highly selective vagotomy (HSV) by determining the gastric emptying rates of isotonic saline and glucose. In 15 controls and 15 patients after HSV, 750 ml of saline and glucose respectively were introduced into the stomach with an interval of two hours. Twenty minutes after each infusion had been started the content of the stomach were aspirated. Phenol red was added as a marker in order to obtain information about the amount of gastric secretion plus possible duodenal regurgitation. In the controls the mean volume of gastric contents recovered was 208 ml after saline and 539 ml after glucose. The corresponding mean volume of test meal remaining was 158 ml after saline and 465 ml after glucose. In patients after HSV the figures for gastric contents were 81 ml after saline and 303 ml after glucose and for meals remaining 59 ml after saline and 259 ml after glucose. The data indicate that HSV speeds the gastric emptying of liquids, while liquids of different compositons are still emptied at different rates, indicating the preservation of a control of the gastric emptying.

Gastric emptying of organic acids in the dog.

Test meals of 300 ml. of six different organic acids were instilled into the stomach of six healthy mongrel dogs. Citric, acetic, propionic, lactic, tartaric and succinic acid were given in 50, 100, 150, and 200 mN concentrations. 2. During the emptying process, the gastric contents were aspirated and immediately re-instilled at 10 min intervals, and the following parameters were recorded: volume, concentration of the organic anion, pH, hydrogen ion concentration and osmolarity. 3. By multiple stepwise regression analysis, the combination of parameters which most effectively determines gastric emptying rate was found to be: concentration of the organic anion, followed by intragastric volume and number of previous test meals given on the same day. These three parameters appear in the equation for gastric emptying rate in which the individual characteristic of each acid is expressed by a constant. 4. Among the various acids, inhibition of emptying rate increases with rising number of carboxylic groups of the acid and its molecular weight. 5. After proximal gastric vagotomy, emptying rate of organic acids is independent of volume, and emptying approaches an exponential pattern. 6. A model for gastric emptying of organic acids with at least three different receptors is proposed: one for the structure of the organic acid, one for concentration and one for intragastric volume.

A method for estimating blood meal volume in Aedes aegypti using a radioisotope

A study was conducted to determine the feasibility of measuring blood meal volume in Aedes aegypti using a radioisotope blood label in lieu of weight differentials. This mosquito species defaecated numerous droplets of a clear fluid beginning while blood feeding was in progress and continuing for up to 3 hr post-feeding. Excretion of this clear fluid occurred regardless of the age or prior nutritional conditioning of the mosquito. When mosquitoes were fed on blood labeled with Ce-144, this radioisotope remained completely with the blood meal and was not passed in the clear excreta. When blood meal volumes were estimated using the radioisotope method, significantly greater values were obtained compared to those calculated by the classical weighing method. A direct relationship was demonstrated between blood meal volume and the quantity of clear fluid excreted. Consequently, the error inherent in the weighing method was increased in mosquitoes taking large blood meals. Ce-144 did not label red blood cells but remained in the plasma. The radioisotope was completely expelled with the blood meal excreta. This technique is compared with related methods previously described. Its applications to problems in mosquito physiology and vector potential are discussed.

A relation between the energy of food and gastric emptying in men with duodenal ulcer.

Using information about the volume and energy density of meals, results from the literature on gastric emptying for healthy men can be marshalled into a consistent body. The same process applied to the published papers on men with duodenal ulcer shows that they have abnormally rapid gastric emptying, especially for meals of high-energy density. This provides confirmation of the view of Shay (1944) that the slowing of gastric emptying by duodenal receptors is less in men with duodenal ulcer than it is in healthy men.

The volume and energy content of meals as determinants of gastric emptying.

1. Results were collected from thirty-three published and unpublished studies of gastric emptying. The volumes of the meals ranged from 50 to 1250 ml., and composition varied from pure carbohydrates to ordinary food. 2. From the published composition of the meals, their nutritive density, as kcal/ml. (4-18 KJ/ml.) was computed: it ranged from zero to 2-3 kcal/ml. 3. The volume of each meal, or test meal, delivered to the duodenum in 30 min was determined, assuming that gastric emptying was exponential. 4. The greater the nutritive density of a meal, the less was the volume transferred to the duodenum in 30 min. The original volume of meal given was not a determinant of the rate of emptying (ml./min). 5. The slowing of gastric emptying with a meal of high nutritive density was not sufficient to prevent an increased rate of delivery of energy to the duodenum (nutritive density times volume delivered in unit time) with a meal of high nutritive density. 6. Assuming an appropriate relationship for the interaction of a stimulus (kcal/ml.) and duodenal receptors, it was possible to predict a rate of gastric emptying for each meal, given its nutritive density. Knowing the initial volume of the meal, it was possible to predict the mean half time for its emptying. 7. There were eight sets of anomalous results: in four the volumes of meal given were less than 200 ml.; explanations of the anomalies in the other four results could not be provided. 8. The results are consistent with equal slowing of gastric emptying by the duodenal action of the products of digestion of isocaloric amounts of fat, protein and carbohydrate, for example, 4 g fat or 9 g carbohydrate, both 36 kcal, taking carbohydrate and protein as 4 kcal/g and fat as 9 kcal/g.

Actions of glucose and potassium chloride on osmoreceptors slowing gastric emptying.

1. Five subjects were given 373 test meals of 750 ml. water containing a range of concentrations of glucose or potassium chloride.2. The greater the concentration of solute in the meals, the greater was the volume of the test meal recovered from the stomach after a fixed time.3. When the concentrations of the solutes were expressed as m-osmole/l. corrected by osmotic coefficients based on vapour pressures at 37 degrees C, glucose and potassium chloride were indistinguishable in slowing gastric emptying.4. These results are consistent with the regulation of gastric emptying by a duodenal receptor responding to osmotic pressure.5. Potassium chloride was more nauseating than glucose on an osmolar basis.

Gastric emptying in young pigs.

1. Gastric emptying in young pigs has been studied by using a serial test meal procedure.2. Phenol red was used as a reference substance. In acute experiments the recovery of phenol red from the stomach with the pylorus occluded was 94.8 +/- 2.2 (S.E.)% of that introduced.3. Gastric emptying was examined in seven fasted conscious pigs provided with a chronic gastric cannula. After emptying the stomach 500 ml. of a liquid meal containing 20 g citrus pectin, 35.0 g sucrose and 100 mg phenol red made up to 1 l. was introduced. After 5-60 min the meal was withdrawn, the volume of meal that had left the stomach was assessed from the recovery of phenol red and the secretion of gastric juice was calculated from the dilution of phenol red and the rate of emptying. After an initial very rapid outflow, the rate of emptying fell with time, as did the rate of secretion.4. In three pigs 200, 400, 600 or 800 ml. meal was introduced into the stomach and the stomach was emptied 20 min later. The rate of gastric emptying varied directly with the volume of meal introduced.5. Atropine sulphate, 0.5 mg/kg body weight, injected I.M. 30 min before the test, greatly inhibited gastric emptying and secretion.

Gastric and Intestinal Transit in Rats Measured by a Radioactive Test Meal

Abstract Measurements of the passage of a Ba 133 SO 4 test meal through the stomach and small intestine of the rat were made under various test conditions and after drug treatment. These measurements consisted of: (1) the percentage of the total Ba 133 SO 4 emptied by the stomach and each successive segment of the small intestine; (2) the ratio of the output from a given segment to its input, the intestinal transit ratio; and (3) the emptying half-time. The passage of the meal was influenced by the volume of meal administered, the body weight of the test animals, and by the concentration of trisodium citrate in the meal. Drugs which enhanced cholinergic mechanisms enhanced emptying also, e.g., methacholine, insulin, 2-deoxy-D-glucose, metoclopramide, and reserpine. Atropine, an anticholinergic, delayed emptying. The following drugs also delayed emptying, e.g., morphine, oxethazaine, chlorpromazine, and the ganglionic blocking drug Ntert-butyl-1-4-butanediamine. The mechanisms controlling stomach emptying and intestinal propulsion were differentially influenced by several of the drugs studied.

Plasmodium cynomolgi: The comparative infectiousness of individual rhesus monkeys

Five rhesus monkeys were infected with the malaria parasite Plasmodium cynomolgi Mayer. Anopheles stephensi Liston mosquitoes were fed on each monkey over the period of prepremunitive gametocytemia. Individual monkeys did not differ significantly in either mean daily gametocyte count (median = 1300 gametocytes per mosquito blood meal volume per day) or mean daily oocyst production (median = 34 oocysts per mosquito per day). Significant differences among monkeys in daily oocyst/gametocyte conversion ratio were attributable to essentially random correlation effects. The observed range in duration of the period of prepremunitive gametocytemia was 14–43 days. Total oocyst production over this period, as calculated for a unit mosquito biting rate of one per day, ranged from 130 to 2800 oocysts. The overall efficiency of conversion of gametocytes to oocysts in A. stephensi was estimated at 0.02 oocysts per gametocyte.

Measurement of gastric acid secretion in the rat by test meal: effects of distension, pentagastrin and propantheline.

Accuracy of a modified test meal technic was assessed by measurement of gastric acid secretion and emptying in male Wistar rats under various conditions. Secretion was higher when a 10% dextrose solution was given during fasting, than when only water was allowed. A 48-hour fast with 10% dextrose solution ad libitum was optimal. The coefficients of variation, for acid output and gastric emptying obtained by duplicate tests under resting conditions, ranged from 18 to 30%. Oral propantheline bromide inhibited acid secretion. The degree of inhibition was similar for measurements by test meal and after pyloric ligation. Pentagastrin produced a highly significant increase in acid secretion. The dose required to evoke a maximal response is considerably higher in the rat than in man. Serial measurements, with test meal volumes of 5, 7.5 and 10 ml, and with graded doses of pentagastrin, revealed no relationship between gastric acid secretion and test meal volume. Hence, distension may be physiologically unimportant in the control of gastric secretion in this species; assessment of secretion by test meal does not require that test meal volume be regulated accurately according to the size of the rat. Incomplete emptying of the stomach, and failure to recover all marker (phenol red) at the end of the test period, result in overestimation of gastric emptying and, to a lesser extent, of acid secretion. The significance of these errors can be minimized by the use of a large volume test meal.

Regulation of blood meal size in the mosquito

In order to determine the rôle played by the central nervous system in regulating blood meal size, the ventral nerve cord was cut at various sites along its length in the female mosquito, Aedes aegypti. When the cord was cut anterior to the second abdominal ganglion, massive hyperphagia resulted, many females ruptured, and blood intake was more than four times that of the untreated controls. As the site of the operation was moved stepwise posteriorly leaving more ganglia connected to the brain via the ventral nerve cord, the degree of hyperphagia and quantity of ingested blood was reduced. On the basis of these observations it was concluded that the termination of feeding was initiated by segmental abdominal stretch receptors which act in concert and signal the presence of optimal blood meal volume to the brain. Five additional mosquito species were tested for hyperphagia and all ingested three to four times the normal blood meal volume when the ventral nerve cord was cut. Females with the nerve cord severed showed normal ovarian development and egg formation, but oviposition was inhibited.

The moon-shaped fundal defect of hiatus hernia: a new radiological sign. Report of nine cases.

SummaryA new radiological sign of diaphragmatic hernia is described. This consists of a moon‐shaped defect in the gastric fundus immediately to the left of the cardio‐oesophageal opening. It is seen with a small volume of barium, 25 ml., in the supine position. Normal barium meal volumes do not usually reveal the defect. When the hernia is produced the defect is usually not seen. The mechanism of production seems to be that prior to actual herniation, that portion of the fundus which is to herniate becomes positioned between diaphragm and remaining fundus. Nine cases are reported.

The pattern of gastric emptying: a new view of old results.

1. Gastric emptying has until now been regarded as exponential in form, but this pattern does not account for all phases of a meal.2. A pattern of emptying in which the square root of the volume of meal remaining declines linearly with time has been shown to account for the experimental results with less error.