Pepsin Concentration Research Articles

Presence of hemagglutinin in the vaccinia virion.

Purified vaccinia virus freed from demonstrable hemagglutinating activity was inactivated and, subsequently, disintegrated by treatment with pepsin. The preparations obtained were examined in the electron microscope and tested for hemagglutinating and precipitating activity as well as for their immunogenicity. The release of hemagglutinating activity from the virions was dependent upon the concentration of pepsin used. Precipitinogens and antigen capable of inducing complement fixing antibodies in rabbits were released by low concentrations of pepsin. Formation of neutralizing and especially hemagglutination inhibiting antibodies was induced by preparations obtained by treatment with higher concentrations of pepsin. Immunization with one mg, but not with 0.1 mg, of inactivated but undigested virions resulted in formation of hemagglutination inhibiting antibodies. The site of a hemagglutinin component in the vaccinia virion is discussed.

Pepsin-Digestibility Method for Animal Proteins

Abstract The official method for pepsin digestibility of animal proteins, 7.040-7.046, has been improved by replacing the centrifuge isolation of the indigestible residue with filtration through glass fiber paper. The modified method was studied by 25 collaborators. The study included meat meals, digester tankage, fish meal, blood meal, poultry by-product meal, and hydrolyzed feathers. The filtration method is more rapid, less laborious, and free from decantation losses. Basic digestion conditions of the official method, pepsin concentration, acidity, digestion time and temperature, and continuous agitation, are unchanged. The study also included grinding the portion of the samples that was larger than 20 mesh. Agreement between replicates in individual laboratories was excellent. Agreement between laboratories on all samples except poultry byproduct meal and hydrolyzed feathers was satisfactory; standard deviations ranged from 0.43 to 1.07. Data indicate that part of the variation was due to slight differences in the samples. The modified method has been adopted as official first action for all animal proteins except poultry by-products and hydrolyzed feathers.

Acid and pepsin secretion in response to insulin after truncal vagotomy in man.

The acid and pepsin responses to insulin stimulation were studied during 22 insulin tests on 21 vagotomized patients. In 9 tests, no rise in acid or pepsin concentration was observed within the two fi

Sensory deprivation on visceral activity. II. The effect of auditory and vestibular deprivation on canine gastric secretion.

A range for gastric acid output and pepsin concentration was determined in 4 dogs with gastric cannulas. The auditory and vestibular inputs for each dog were then eliminated. A marked inhibition of gastric secretory output occurred in all dogs over a 4-month period.

Sustained Gastric Secretion in Response to 2-Deoxy-d-Glucose: Indefatigability of the vagal mechanism

The effect of sustained vagal nerve stimulation by continuous intravenous infusion of 12.5 mg per kg-hr of 2-deoxy- d -glucose was studied in dogs with simple gastric fistulas. Gastric juice volume, hydrogen ion content, and electrolyte and pepsin concentration and output were measured as were serum electrolytes and sugar. Levels of acid and pepsin secretion formed a plateau after 2 to 3 hr which was maintained without evidence of fatigue for 24 hr. Hourly acid output approximated two-thirds or four-fifths of the response to 0.05 mg per kg of histamine base given subcutaneously or 150 mg per kg of 2-deoxy- d -glucose given intravenously, respectively. An essential component of the thesis which claims vagally driven gastric acid hypersecretion as a critical feature of duodenal ulcer diathesis is a physiological possibility.

The action of caerulein on gastric secretion of the chicken

Caerulein stimulated gastric secretion of the chicken, particularly after intravenous infusion. The threshold doses given by subcutaneous and intravenous injection were 10 ng/kg and 50 ng/kg respectively. Caerulein increased output of the fluid and solid components of gastric juice and generally raised the concentration of pepsin. Slight tachyphylaxis particularly on the fluid and acid components was observed. Caerulein stimulation of gastric secretion was completely inhibited by atropine but unaffected by drugs altering histamine stores. Caerulein was four time as effective on fluid and acid secretion than human gastrin I, and fifteen times as effective on pepsin secretion. Porcine secretin did not affect the chicken's gastric secretion.

The effect of visual deprivation on canine gastric secretion.

In 13 dogs with gastric cannulas the acid output per hour was determined after: (a) subcutaneous injection of 0.1 mg histamine (base), (b) subcutaneous injection of 1.0 mg histamine (base), (c) teasing with meat (10 min interval), (d) intravenous injection of 1.0 units/kg of insulin. The pepsin concentration was also determined after the intravenous injection of 1.0 units/kg of insulin. The range and average acid output and pepsin concentration were established for each test condition per dog. Vision was compromised in the dogs by ablation of the orbits, collapse of the orbits, and by occipital cortical lesions. Gastric secretory studies were repeated at intervals over a 4 month period. There was marked inhibition of acid output and pepsin concentration in all dogs for the entire 4 month period to all gastric stimuli.

Abomasal secretory responses to teasing with food and feeding in the sheep.

1. Secretion of acid and pepsin from abomasal pouches and contractions of the reticulum and rumen were studied in sheep. Observations were made in sheep after being fasted and when they had food available ad libitum.2. The abomasal pouches were of fundic regions alone and also of the fundic region with a rim of antral mucosa.3. The secretion from both types of pouch was continuous, was increased by feeding and decreased by fasting.4. The volume, pepsin concentration and acid concentration of the secretion from fundic pouches increased within 15-30 min of the sheep being teased with food or fed. These responses were observed in sheep which had food available ad libitum or had been fasted.5. Reticulum contractions and the rumen contractions associated with them (A sequences) increased in frequency when sheep with either type of pouch were teased with food or when they ate.6. Consistent associations between rumination and abomasal secretory activity were not established.7. Mixed fundic-antral pouches did not characteristically show responses to teasing with food and sustained secretory responses were delayed by up to 90 min after feeding commenced.8. It is suggested that a cephalic phase of gastric (abomasal) secretion was revealed in the studies on fundic pouches of the abomasum.

Duodenal inhibition of gastric secretion by osmotic agents in normal subjects and patients with duodenal ulcer

Gastric secretion in man is inhibited by the presence in the duodenum of hyperosmolar and hypoosmolar solutions. Both acid and pepsin outputs are affected. There is no change in hydrogen, sodium, or potassium ion concentration in the gastric juice. Pepsin concentration, however, is reduced by all inhibitory stimuli. Inhibition is thought to act directly upon parietal and chief cells, and a possible basis for this mechanism is discussed. The response is similar in control subjects and duodenal ulcer patients; there is in particular no evidence of impaired inhibition in the ulcer group. An anomalous feature is the relatively small inhibition of acid output after hypertonic saline in control subjects compared with the duodenal ulcer patients.

Atropine Inhibition of Insulin-, Histamine-, and Pentagastrin-Stimulated Gastric Electrolyte and Pepsin Secretion in the Dog

Atropine (80 µg per kg) was injected intravenously into 9 fistula dogs secreting in response to insulin hypoglycemia, causing immediate (100%) and prolonged (>21½ hr) inhibition. The same dose was given 90 min after the start of a continuous infusion of either pentagastrin (1.5 µg per kg-hr) or histamine (1 mg base per hr). Histamine-stimulated volume output fell by about 30%, and pepsin output fell by 80 ro, but electrolyte composition was largely unchanged, whereas gastrin effects were blocked 75 to 95% and comprised a large drop in volume, as well as decreases in Cl−, H+, and K+ concentrations and a rise in Na+ concentration. Pepsin concentrations were greatly reduced in both, being higher to start with in the pentagastrin experiments. The action of atropine in inhibiting pentagastrin action emphasizes the similarities between the actions of this group of peptides and cholinergic agents.

The effect of 1-hyoscyamine on gastric secretion of acid and pepsin in man.

After collecting basal secretion for 30 minutes a histamine infusion was started. The infusion speed was increased every 15 minutes. The histamine infusion lasted 1 1/2 hours. During histamine stimulation there was a continuous increase in volume, acid concentration, acid output, and pepsin output for every period. Treatment with 1-hyoscyamine, which prior to the second investigation had been given for at least 2 1/2 weeks, resulted in a lowered volume, acid concentration, and acid output, during all periods of histamine stimulation. The pepsin concentration was also slightly lower for every period during treatment, resulting in a marked decrease in pepsin output.

Experimental Infections of Lambs with Trichostrongylus axei; Investigations using Abomasal Cannulae

Summary An investigation is described in which 2- to 6-month-old calves were infected with 150,000 to 300,000 Trichostrongylus axei third-stage larvae; one calf was challenged with 100,000 Ostertagia ostertagi third-stage larvae, and changes in constituents of the abomasal fluid were observed by the use of abomasal cannulae. Injection resulted in an increase in the abomasal fluid pH, pepsin and Na+ concentration, and a decrease in the concentrations of K+, Cl’ and dry matter. Changes in the pepsin concentration of the abomasal fluid were associated with similar changes in the serum pepsinogen. Saliva Na+ and K+ concentrations showed similar, but variable, alterations to Na and K values in the abomasal fluid. In lethal infections, the rise in abomasal pH was parallel with a decrease in the faecal dry matter percentage, and when the pH increased above 6 0 a terminal phase resulted where a marked weight loss occurred, serum albumin levels decreased and haemo-concentration occurred. The infection with O. ostertagi produced similar changes and differed only in the presence of a higher and sustained increase in serum pepsinogen.

Antral function in duodenal ulcer. The gastric secretion of acid, chloride and pepsin in response to antral stimuli and to insulin and maximal histamine stimulation in duodenal ulcer and controls.

Summary A dye-dilution technique is used to compare the concentration and output of acid, chloride and pepsin in duodenal ulcer patients and controls following stimulation of the antrum with alcohol, sodium bicarbonate and peptone with the response to insulin hypoglycaemia and maximal histamine stimulation. The mean secretory rate was higher in response to all the stimuli in duodenal ulcer patients except to sodium bicarbonate. Following antral stimulation by peptone and sodium bicarbonate the acid and chloride concentrations rose to very high levels. The mean outputs were the same as those following maximal histamine stimulation although there were wide individual variations. There was no difference between duodenal ulcer patients and controls. The ‘neutral chloride’ concentration was much less than in the other phases. The basal secretion and the secretions in response to insulin and histamine stimulation showed higher concentrations, as well as higher outputs of acid and chloride in duodenal ulcer patients. Pepsin concentration in response to the various stimuli showed no difference between duodenal ulcer patients and controls and the pepsin output reflected the changes in secretory volume.

CRITICAL STUDIES OF THE PYLORUS LIGATED RAT (SHAY RAT)

The pylorus ligated rat (Shay rat) was described by Shay et al. (1) for the production of acute ulcers in the forestomach, and it has been also employed as a means of studying gastric secretion. This technique is now used extensively as a screening method of gastric secretory depressants and antipeptic ulcer agents (2-4) because of the following advantages: 1) the simplicity of surgical procedure, 2) the high rate and rapid occurrence of ulceration, and 3) the possibility of measurements of gastric secretory rate and severity of ulceration in the same animals; which make up for the shortcoming that ulcers are present only in the forestomach. The pathogenesis of ulceration in the pylorus ligated rat has been discussed by many investigators, but the definite conclusion is not yet offered. Several factors have been considered as causes of ulceration; such as the digestive effect of gastric juice, the interference of blood circulation or the decrease of mucosal resistance. Sun and Chen (5) concluded that the rumenal ulcers in the pylorus ligated rat might be merely a result of the volume and the concentration of gastric hydrochloric acid and pepsin upon the mucosa. But other factors can not be ruled out completely. There remains some obscurities also in the gastric secretory mechanism of the pylorus ligated rat. It is often said that the pylorus ligated rat is inadequate for the estimation of stimulants of gastric secretion, for they can hardly increase in gastric secretion in response to stimuli owing to the hypersecretion. The mechanism of the hypersecretion in the pylorus ligated rat is now still controversial. The present study is an attempt to clarify the effects of various factors on gastric secretory rate and ulceration and to discuss the mechanisms of ulceration and gastric hypersecretion in the pylorus ligated rat.

The actions of caerulein on gastric secretion of the dog and the rat.

1. Caerulein, as expected from its amino-acid composition and sequence, has a potent stimulant action on gastric secretion in the dog, the rat and the frog.2. In the denervated fundic pouch of the dog, caerulein increases the rate of flow of gastric juice and the outputs of acid and pepsin. Acid concentration and pepsin concentration in caerulein-produced juice are generally greater than in control juice. The threshold subcutaneous dose of caerulein is 0.15-0.5 mug/kg and the threshold rate of intravenous infusion 0.25-0.5 mug/kg per hr. Rapid intravenous injection is ineffective. On a molar basis, caerulein is approximately twice as active as human gastrin I on volume and acid output of the gastric pouch and 4 times as active on pepsin output.3. Sustained acid secretion of the fundic pouch produced by histamine infusion is inhibited by caerulein, administered either intravenously or subcutaneously. In turn, acid secretion elicited by caerulein is inhibited by atropine.4. In the rat, the activity ratio of caerulein to human gastrin I is 7-30, calculated on a molar basis, and is thus considerably greater than in the dog. Further, caerulein is 3 times more active than cholecystokinin-pancreozymin. Tested on the perfused stomach preparation of the rat, the threshold dose of caerulein by rapid intravenous injection is 25 ng/kg, by intravenous infusion 0.25 mug/kg per hr, and by subcutaneous injection 0.25 to 0.5 mug/kg.5. The activity of caerulein is sharply reduced by pretreatment of the rats with the histamine liberator 48/80 and potentiated by pretreatment with the diamine oxidase inhibitor aminoguanidine. When caerulein is given by rapid intravenous injection during a priming infusion of histamine its effect is enhanced and considerably prolonged.6. The isolated mucosa of the frog stomach is extremely sensitive to caerulein which, in a concentration of a few pg/ml., stimulates active transport of chloride.7. Qualitative and quantitative differences in the action of gastrin and caerulein are pointed out, and particular emphasis is laid on the importance of esterification of the tyrosyl residue for the biological activity of caerulein.

Comparative effects of tetragastrin and histamine on pepsin secretion in man.

The pepsin concentration and output in the gastric secretion were measured in nine men with duodenal ulcer, after stimulation with tetragastrin, 20 μg/kg, and histamine acid phosphate, 40 μg/kg.After histamine the pepsin secretion was higher than after tetragastrin. The ‘optimal’ dose of tetragastrin —which will cause the greatest output of pepsin—is not known. The construction of a dose-response curve for tetragastrin/pepsin may solve this problem.

Relationship between hydrogen ion and pepsin concentration in human gastric secretion.

Relationship between hydrogen ion and pepsin concentration in human gastric secretion.

Effect of a synthetic sulfated polysaccharide (SN-263) on gastric peptic activity in humans.

SummaryThe effect of oral administration of a synthetic sulfated polysaccharide, amylopectin sulfate (SN‐263), on gastric peptic activity was studied in 49 patients with chronic duodenal ulcer. Five dose levels were studied: 100 mg, 200 mg, 300 mg, 500 mg, and 800 mg. A significant depression of gastric peptic activity was observed after oral administration of 200 and 300 mg of SN‐263. This inhibitory action appeared within 15 min and lasted for 45 min. At higher dose levels of 500 and 800 mg, a longer duration of inhibition lasting for 75 min was observed. Oral administration of 100 mg of SN‐263 was ineffective as an anti‐peptic agent. SN‐263 had no effect on the acidities of the gastric contents.When 200 mg of SN‐263 was given at two‐hour intervals, the inhibitory effect of the second administration of SN‐263 on gastric pepsin concentration was similar to that of the first dose. There was no evidence of a cumulative action. The addition of an anticholinergic drug, propanthelie bromide, which will inhibit acid and pepsin secretions at their source, further enhanced the action of SN‐263 as an antipeptic agent. Since SN‐263 exerts no antacid or anticholinergic action, its inhibitory effect on peptic activity must be a direct one.

Relation between inhibition of gastric secretion and absorption of fatty acids.

Gastric secretion stimulated by a 100-g meat meal was inhibited by oleic acid and triolein and the inhibition correlated with absorption of the respective lipids in dogs with vagally innervated gastric pouches. Twenty-six milliliters of lipid were infused into the duodenum at 0.76 ml/min through a duodenal fistula starting 5 min before feeding. Gastric secretion was collected every 30 min and analyzed for acid and pepsin concentrations. Paraffin oil infused at the same rate gave results similar to feeding alone. Lipid absorption was determined by measuring venous plasma radioactivity at 1, 2, 3, 4, and 6 hr after feeding and infusing of C14-labeled oleic acid or triolein. Lipid in intestinal content for 3 hr after feeding was determined in acute experiments. The duration of gastric inhibition was longer and the absorption was slower with oleic acid than with triolein.

Biochemical, Serological and Haematological Changes Associated with Infections of Calves with the Nematode Parasite, Ostertagia Ostertagi

(1) Blood and abomasal contents have been analysed from about 80 cattle with natural and experimental infections with Ostertagia ostertagi , and also parasite-free calves. (2) Heavy infections resulted in serum albumin levels falling to 1.3 to 1.6 g./100 ml. Anthelmintic treatment followed by heavy concentrate feeding indoors resulted in rapid increases in serum albumin. (3) Packed cell volume estimations support the view that haemoncentration is associated with the fall in albumin level in early infection and that haemodilution occurs as albumin rises after treatment. (4) Heavy infections were characterized by high pH and low pepsin concentrations in the abomasum at slaughter and these changes were evident, to a lesser degree, in moderate infections. These changes suggest that gastric function must be markedly reduced in heavy infections.