Increased sensitivity to stimulation of acid secretion by pentagastrin in duodenal ulcer.

The effect of graded doses of pentagastrin (2.7-6,000 ng/kg times h) on gastric acid secretion was measured in 20 duodenal ulcer (DU) and 20 non-DU subjects. Confirming many previous studies, the mean observed highest response and the mean calculated maximal response were significantly greater in DU than in non-DU subjects. The mean dose (plus or minus SE) in ng/kg times h for half maximal response, calculated from responses corrected for basal secretion and normalized for maximal secretion, was 92.1 plus or minus 1.7 in DU and 246.8 plus or minus 24.6 in non-DU subjects, a significant difference. By parallel line bioassay non-DU subjects required 2.8 times more pentagastrin (95% confidence limits 2.1-3.7) than DU highest response. Thus, this study shows that, compared with non-DU subjects, DU patients not only secrete more acid in response to stimulation by pentagastrin but also are more sensitive to stimulation by pentagastrin, that is, need smaller doses to achieve the same fraction of maximal response.

Isolation and characterization of an abnormal human intrinsic factor.

A patient has been described previously who presented at age 13 with vitamin B(12) (B(12)) deficiency secondary to a functionally abnormal intrinsic factor (IF). IF has now been isolated from the gastric juice of the patient, his sister, and both parents, who are first cousins, by using affinity chromatography on B(12)-Sepharose. Patient IF appeared normal in terms of (a) B(12) binding, (b) mol wt, (c) total amino acid and carbohydrate composition, and (d) immunodiffusion with rabbit anti-patient and anti-normal IF sera. After adsorption with normal IF, however, anti-patient IF serum precipitated the various IFs as follows: patient IF (> 95%); mother, father, and sister IF (50%); and normal IF (< 10%). Additional adsorption with mother, father, or sister IF completely inhibited the precipitation of patient IF. The association constant determined for patient IF-B(12) and human ileal mucosal homogenates (0.1 x 10(9) M(-1)) was 60-fold lower than that determined with normal IF-B(12) (6.0 x 10(9) M(-1)). Intermediate amounts of ileal IF-B(12) binding were observed with mother, father, and sister IF-B(12). These in vitro studies were supported by multiple Schilling tests, performed with a totally gastrectomized volunteer, that gave the following mean urinary excretions of [(57)Co]B(12): free B(12) (0.5%); + patient gastric juice (2.6%); + mother or father gastric juice (17%); and + normal gastric juice (26%). These studies demonstrate that the patient is homozygous and that the mother, father, and sister are heterozygous for a structurally abnormal IF that has a markedly decreased, but not absent, affinity for ileal IF-B(12) receptors. These studies also indicate that the B(12) and ileal binding sites are located on different portions of the IF molecule.

Gastric acid secretion rate and buffer content of the stomach after eating. Results in normal subjects and in patients with duodenal ulcer.

New methods are described by which the buffer content and the rate and pattern of net gastric acid secretion in human subjects fed normal meals can be measured by use of sodium bicarbonate infusion to control intragastric pH. With these techniques, it was shown that the rate of acid secretion in response to a steak meal in seven duodenal ulcer patients was twice the rate achieved in six control subjects and that the amount of acid secreted after eating exceeded the peak histamine response in the ulcer patients but not in the controls. Meal-stimulated acid secretion, expressed as a function of the peak histamine response, was roughly correlated with the serum gastrin concentration (r = 0.45), but it was concluded that other factors must also contribute to the higher than normal secretory responses to a meal found in duodenal ulcer patients. Measurement of buffer content of the stomach revealed that the duodenal ulcer patients emptied the meal buffer at a much more rapid rate than the normal subjects. By 2 h after eating, the ulcer subjects had less than half as much buffer in their stomachs as the controls. The combination of acid hypersecretion and rapid buffer emptying leads to abnormally high gastric acidity after a meal in duodenal ulcer patients. These results suggest that, in addition to a large parietal cell mass, parietal cell responsiveness to a meal and the rate of buffer emptying may be important in the pathogenesis of duodenal ulcer.

Gastric cancer in Colombia. IV. Nitrite and other ions in gastric contents of residents from a high-risk region.

Samples of gastric contents from 2 groups of patients from a region of high risk for gastric cancer were analyzed for pH, nitrite, nitrate, thiocyanate, and chloride. In each group, the patients could be divided into 2 subgroups: those with a gastric pH of less than 5 and those with a gastric pH of greater than 5. Above pH 5, nitrite was correlated with nitrate. The pH greater than 5 subgroups had significantly higher (P less than 0.01) nitrite content (20- to 100-fold). Some high- and low-nitrite samples were also analyzed for macro and trace metal ions, but differences were not significant. This is the first report in which patients with diagnosed gastric pathology related to a precancerous state were shown to have high levels of a putative carcinogen precursor. The results were compatible with our original hypothesis of intragastric nitrite formation by bacterial reduction of nitrate and concomitant synthesis of carcinogenic N-nitroso compounds.

Diet and chronic atrophic gastritis: a case-control study.

A hospital-based case-control study of gastric cancer precursor lesions was conducted in a high-risk black population in southern Louisiana. Ninety-three subjects with biopsy-proved advanced chronic atrophic gastritis were compared to two control series: a gastroscopy clinic series and a general hospital-admission series. Dietary case-control differences indicated a protective effect associated with fruit and vegetable intake and with dietary vitamin C and a risk elevation associated with milk consumption. The protective effect associated with consumption of fruits, vegetables, and vitamin C is consistent with findings for gastric cancer and with the etiologic hypothesis of intragastric nitrosation. A twofold increased risk was associated with cigarette smoking. Gastric juice pH, NO3-, and NO2- were determined for subjects undergoing gastroscopy, and comparisons were made between this high-risk U.S. group and a Colombian population with a much greater magnitude of risk; the latter had higher NO3- and NO2- levels. An increase in pH was associated with increasing severity of gastric lesions. Levels of pH and NO2- concentration were significantly correlated (P less than .0005); however, in Louisiana the large difference in NO2- concentration associated with pH elevation is not associated with histopathologic severity. Divergent trends with severity of lesions for NO3- concentration were seen in the two populations.

Stability of lingual lipase in vivo: studies of the iodinated enzyme in the rat stomach and duodenum.

In order to examine the stability of purified lingual lipase (EC 3.1.1.3) in vivo under fasted and fed conditions, we iodinated rat lingual lipase to a specific activity of 5-10 microCi/micrograms protein with 125I-labelled Bolton-Hunter reagent. Labelled lingual lipase in either saline or Intralipid was administered via an intragastric or intraduodenal cannula. Control labelled lipase preparations were incubated at 37 degrees C. Serial aliquots of gastric or intestinal contents were aspirated and subjected to SDS-polyacrylamide gel electrophoresis followed by autoradiography, and quantitated by densitometric scanning. In all experiments, the amount of lingual lipase in both stomach and duodenum was significantly reduced (P less than 0.05 vs. controls) at 15 and 60 min after administration. In either the presence or absence of Intralipid, lingual lipase was more stable in the stomach than in the duodenum (P less than 0.05). In conclusion, lingual lipase was more stable in the stomach than in the duodenum, and lipid emulsion did not appreciably affect the stability of the enzyme in either location of the upper digestive tract of the rat.

A new principle in biospecific affinity chromatography used for purification of cobalamin-binding proteins.

To avoid using protein-denaturing agents for desorption, when purifying cobalamin-binding protein by biospecific affinity chromatography, an affinity column has been prepared where cobalamin is attached through a temperature-labile linkage to insolubilized 3, 3'-diaminodipropylamine. On desorption the protein is obtained in solution saturated with cobalamin. The method has been used for purification of intrinsic factor and transcobalamin I.

Effect of glycosidases and proteinases on cobalamin binding and physicochemical properties of purified saturated haptocorrin and intrinsic factor.

The effect of exoglycosidase, N-glycanase, trypsin and chymotrypsin was studied on the binding capacity and physicochemical properties of intrinsic factor and of haptocorrin using Superose 6 gel filtration. Intrinsic factor was purified as recently described by us. Haptocorrin was purified 6000-fold from human saliva using thermolabile affinity chromatography and high-performance cationic exchange chromatography with a specific activity of 20.6 nmol of cobalamin (Cbl) per mg protein and a yield of 44.7%. Exoglycosidases provoked a decrease of 54.3 and 78.2% of the Cbl binding capacity of haptocorrin and intrinsic factor, respectively. The sequential incubation of haptocorrin and intrinsic factor wit exoglycosidases and proteinases provoked a decrease of, respectively, 100 and 92.7% of their Cbl binding capacity, whereas the incubation with proteinase decreased the Cbl binding capacity of, respectively, 67.9 and 7.9%. The result of the incubation of [3H]intrinsic factor or [3H]haptocorrin with chymotrypsin and trypsin gave, respectively, no change in the elution position and a shift corresponding to a decrease of 50% of the estimated molecular mass. The estimated molecular mass of Cbl-intrinsic factor and of Cbl-haptocorrin decreased, respectively, to 57.1 kDa and to 88.1 kDa after incubation with exoglycosidases. It was concluded that (1) the carbohydrate core of intrinsic factor protects the whole protein whereas the carbohydrate core of haptocorrin protects only half part of the protein and (2) the carbohydrates are implicated in the formation of the cobalamin binding site of haptocorrin and intrinsic factor.

Sleep patterns and gastric acid secretion in duodenal ucler disease.

Five normal volunteers and five patients with duodenal ulcer (DU) disease were studied for five consecutive nights. All subjects underwent placement of a nasogastric tube, continuous collection of gastric juice, and continuous electroencephalographic monitoring of sleep. Gastric juice was collected in 20-minute samples by remote suction (Gomco). Blood samples were drawn every 20 minutes on the third night via an indwelling venous needle. Results showed no significant correlations between the sleep variables and the gastric acid secretion measures or between the sleep variables and serum gastrin levels. Acid secretion decreased from hour 1 to hour 2 in controls and in patients with inactive DU disease, while it increased in patients with active DU disease. Each subject had at least one night of recording in which continuous gastric secretion was less than 0.1 mEq per 20-minute sample. It appears unlikely that the gastric discomfort of DU patients can be attributed to acid hypersecretion triggered by rapid eye movement sleep.

Cimetidine dynamics after single intravenous doses.

Cimetidine dynamics were studied in nine multiple-trauma patients. Mean elimination half-life was 2.27 hr, mean volume of the central compartment was 0.29 l/kg, mean volume at steady state averaged 0.90 l/kg, and mean total body clearance was 9.02 ml/min/kg. After intravenous cimetidine, drug concentrated in gastric fluid reached a peak concentration in 3 hr. Gastric plasma cimetidine ratios after equilibration ranged between 3.0 and 4.3. There was a correlation between cimetidine gastric juice concentration and gastric pH (r = 0.50), but no correlation was found between plasma cimetidine concentration and pH (r = 0.13).

Influence of gastric pH on digoxin biotransformation. I. Intragastric hydrolysis.

3H-digoxin-12 alpha and unlabeled digoxin were administered down a nasogastric tube and digoxin, digoxyigenin and its mono- and bis-digitoxosides, and pH were assayed in gastric fluid of 6 healthy subjects at intervals for 90 min each under 4 conditions: pentagastrin infusion 6 micrograms/kg/hr with the subjects ambulatory and supine, and saline infusion ambulatory and supine. Intragastric hydrolysis occurred at roughly the same rate as reported in vitro. At 90 min, an average of 12.5% of the radioactivity that remained in the gastric fluid was recovered as digoxin for the 2 conditions when pentagastrin was infused, compared with 52.5% for th 2 conditions when saline was infused. The main glycosidic metabolite was digoxigenin and the amount correlated closely with the hydrogen ion activity in gastric fluid at 90 min (r = 0.83, p less than 0.01). Only minor differences were found between the supine and ambulatory conditions. The clinical significance of these results remains to be determined.

Cimetidine dynamics after repeated intravenous injection.

Cimetidine dynamics were studied in six multiple-trauma patients receiving 300 to 600 mg every 6 hr for prevention of stress ulceration. Patients received cimetidine intravenously for a mean duration of 7.8 days. There was a positive correlation between cimetidine serum concentration and gastric pH; the correlation between intragastric cimetidine concentration and gastric pH was stronger. The association between therapeutic efficacy (pH greater than 4) and serum concentration over 1 mcg/ml was significant. The association with gastric cimetidine concentration above 2 mcg/ml was significant.

Purification of human intrinsic factor using high-performance ion-exchange chromatography as the final step.

Human intrinsic factor was purified 1430-fold from gastric juice with a yield of 75% using two steps: labile ligand affinity chromatography and high-performance ion-exchange chromatography. Intrinsic factor precipitated in the presence of specific autoantibodies and 15% sodium sulfate, had an estimated Mr of 59 000 in 5% SDS electrophoresis and could bind to the specific ileal receptor in vitro. Its carbohydrate composition could be related to N-lactosaminic and O-glycosidic chains. High-performance ion-exchange chromatography was a mild, rapid and efficient procedure to separate completely intrinsic factor from haptocorrin (another glycoprotein of gastric juice which binds cobalamin) and from other contaminating proteins.

A new family of growth factor-like peptides. 'Trefoil' disulphide loop structures as a common feature in breast cancer associated peptide (pS2), pancreatic spasmolytic polypeptide (PSP), and frog skin peptides (spasmolysins).

Four peptides present in completely different biological sources have been shown to exhibit a large degree of structural similarity. The peptides include: (i) a 60 amino acid residue breast cancer associated pS2 peptide isolated from human gastric juice and the culture media of the human breast cancer cell line MCF-7; (ii) a 106 amino acid residue pancreatic spasmolytic polypeptide (PSP) isolated from porcine pancreas and pancreatic juice; and (iii) a 49 and 50 amino acid residue peptide predicted from a cDNA isolated from the skin of the frog, Xenopus laevis. These peptides are characterized by having one (pS2 and the frog peptides) or two (PSP) domains of a highly conserved 38-39 amino acid residue consensus sequence not found in any other known peptides or proteins. The domain sequences contain 6 cysteine residues in nearly the same positions and it is suggested that these 6 residues are linked by 3 disulphide bonds to form a characteristic 'trefoil' disulphide loop structure common in all four peptides. From the sources of which the peptides have been isolated and from experiments showing that PSP has a growth factor stimulatory effect on MCF-7 cells, it is further suggested that these peptides may represent members of a new family of growth factors.

Side effects of stress bleeding prophylaxis.

Conventional stress bleeding prophylaxis with antacids or histamine (H2)-antagonists, as well as the newer mucosa-protective drugs pirenzepine and sucralfate, are satisfying most of the clinicians with regard to efficacy of stress bleeding prevention. Therefore, potential side effects are attaining crucial importance with regard to the drugs to be used. Pharmacologic blockade of cardiac H2-receptors increases the risk of bradycardia and negative inotropic effects as well as coronary vasoconstriction at least in the presence of elevated plasma histamine levels. Intracardiac injection of pirenzepine can lead to temporary tachycardia. Elderly patients have been shown to be at an increased risk of side effects to the central nervous system when treated with H2-antagonists. These drugs can also induce toxic effects in the liver. Cimetidine leads to interactions with a number of drugs used in the intensive care unit. In patients with pre-existing pulmonary diseases, H2-antagonists have been demonstrated to increase pulmonary bronchoconstriction. Alkalinization of the gastric juice is associated with a significant increase in colonization of gram-negative bacteria in the stomach. In intubated patients, aspiration of stomach contents occurs in 30 to 40 percent of the patients. A number of studies have shown a direct correlation between alkalinization of the gastric juice and pulmonary infections. Sucralfate and to a lesser degree pirenzepine can reduce the risk of pulmonary infections. Sucralfate also exerts a bactericidal effect. Recent investigations support the hypothesis that alkalinization of the stomach also increases the risk of systemic infections. This may be the main reason for the observation that at least in ventilated patients sucralfate, unlike H2-antagonists or antacids, leads to a significant reduction of the mortality rate compared with conventional stress bleeding prophylaxis.

Histopathology of gastric dysplasias: correlations with gastric juice chemistry.

Based on the experience with gastric biopsies in a rural population of Colombia with very high rates of gastric cancer, a description of the dysplasias of the gastric mucosa is given. It recognizes two main types of dysplasias: hyperplastic and adenomatous. Different degrees of atypism are recognized within each category. A comparison with other classifications of gastric dysplasias is offered. A positive correlation of dysplasia with gastric juice nitrite is found and offered as an adjuvant to the evaluation of patients with this type of condition.

Mutagenic activity in gastric juice and urine of subjects with chronic atrophic gastritis, gastric epithelial dysplasia and gastric cancer.

Gastric juice and urine samples from consecutive patients who underwent endoscopy for upper GI tract complaints were examined for the presence of mutagens. Patients endoscopically and histologically diagnosed as having either chronic atrophic gastritis (CAG) or gastric cancer (GC) had higher than normal levels of mutagens in their gastric juice and urine. The gastric juice pH of these patients was also elevated and, in the case of the CAG patients, contained detectable levels of nitrites. No correlation was however found between gastric mutagen levels and urinary mutagen excretion in the individuals examined.

Mutagenic activity of gastric juice.

Gastric juice samples from patients of a rural area of the Colombian Andes at high risk to gastric cancer were tested for mutagenesis with Salmonella typhimurium strains TA100 and TA1538. Direct mutagenic effect was found in samples with detectable amounts of nitrite. This effect was not accountable by nitrite alone. Nitrite-negative samples from the same area and samples from the low-risk area of Cali were negative using the same mutagenesis assay.

Studies of human lead metabolism by use of stable isotope tracers.

Dynamics of lead metabolism were studied by replacement of a portion of the dietary lead with stable isotope tracers, and maintaining subjects on controlled diets for about 6 months. Results for one subject have been previously reported. Preliminary data are now available for a second subject. Although the data on the two subjects are basically similar, there are also significant differences. The two subjects have different blood lead concentrations (0.25 and 0.18 mug/g). Both subjects received the same dietary and similar atmospheric lead exposure, and the lead concentration of their blood was shown to be nearly in a steady state. The difference in blood lead concentration appears primarily attributable to differences in the fraction of lead absorbed from the gut, although there are also differences in other physiological parameters, as well as probable small differences in their intake of atmospheric lead. The quantity of lead absorbed from a typical urban atmosphere (Pb concentration = 1-2 mug/m(3)) has been shown by our isotopic data and balance studies to be 15+/-3 mug/day. Measurement of the contribution of atmospheric lead to the lead intake of the second subject was also carried out by removal of lead from the atmosphere. Decline in the blood concentration of lead of normal isotopic composition was shown to be equivalent to the removal of 15 g/day. Measurements made during the course of a day show complexities in the absorption and distribution of lead, which are averaged out on a time scale of ca. 5 days.

Microfiltration method for quantitative study of fibrous particles in biological specimens.

Counting coated and uncoated inorganic fibers in sputum has been used to investigate the level of environmental or occupational asbestos exposure and the concentration of fibrous dusts in human lung. Inorganic fibers in sputum were counted by light microscopy after chemical digestion and microfiltration processing. The same method was used for processing gastric juice and lung tissue. There were no ferruginous bodies (FB) in sputum from 49 patients without any asbestos exposure. The study of sputum from 125 patients with various asbestos exposure pointed out a high correlation between the number of FB in sputum and the level of asbestos exposure. These 125 patients were classified into three groups according to the type of their asbestos occupational hazard: group I, raw asbestos workers; group II, workers manufacturing asbestos products; group III, workers with mixed industrial dust exposure. For these three groups, the mean number of FB in sputum was 100, 10, and 1, respectively. The comparison of the FB content of sputum and lung parenchyma showed the absence of FB in sputum when the concentration of FB in lung parenchyma was under 1000/cm(3) of lung parenchyma; above this concentration the number of FB in sputum was in good correlation with fiber concentration in lung parenchyma. A preliminary study with the use of gastric juice showed that gastric juice is a less sensitive sample for evaluating fiber concentration in lung. The microfiltration method for the counting of uncoated fibers gave results as accurate as those in the centrifugation method.