Pepsinogens: genetic polymorphism in man.

Population frequencies of the two patterns of pepsinogen excretion (with and without pepsinogen 5) and family studies indicate that pepsinogen 5 is controlled by a pair of genes, Pg(a) and Pg(b), at a single autosomal locus and that Pg(a) is dominant.

Stable antibody-producing murine hybridomas.

A method is described for obtaining antibody-producing hybridomas that are preferentially retained in cultures of fused mouse spleen and myeloma cells. Hybridomas are produced by fusing mouse myeloma cells that are deficient in adenosine phosphoribosyltransferase (APRT) with mouse spleen cells containing Robertsonian 8.12 translocation chromosomes. The cell fusion mixtures are exposed to a culture medium that can be utilized only by APRT-positive cells, which results in the elimination of both unfused APRT-deficient myeloma cells and non-antibody-producing APRT-deficient hybridomas that arise by segregation of the 8.12 translocation chromosomes containing the APRT genes and the active heavy chain immunoglobulin gene.

Food cobalamin malabsorption occurs frequently in patients with unexplained low serum cobalamin levels.

Malabsorption of food-bound or protein-bound cobalamin with normal absorption of free cobalamin has been described in studies of patients with gastric dysfunction. We used the egg-yolk cobalamin absorption test to study 47 patients selected not because of known gastric disorders but because they had low serum cobalamin levels with normal Schilling test results. Their egg test results were significantly lower than in normal controls, while Schilling test results were normal. Twenty of the subjects had egg test excretion below 1.5%. No features distinguished them from the 27 who excreted more than 1.5% other than the presence of lower pepsinogen I:II ratios. Eight of 19 tested patients with food cobalamin malabsorption had no evidence of abnormal gastric status by blood tests and/or gastric analysis. Also noteworthy was the finding of food cobalamin malabsorption in 60% of tested patients who had neurologic, cerebral, or psychiatric abnormalities. Food cobalamin malabsorption appears to be associated frequently with otherwise unexplained low cobalamin levels. Low cobalamin levels in patients with normal Schilling test results cannot be dismissed as insignificant without also testing for food cobalamin malabsorption, whether or not the patients have known gastric dysfunction.

Hypergastrinemia in obese noninsulin-dependent diabetes: a possible reflection of high prevalence of vagal dysfunction.

To elucidate the relation of noninsulin-dependent (type II) diabetes mellitus to plasma levels of gastrin, pepsinogen I, and pepsinogen II, gastric acid secretion, and gastric emptying, we studied diabetic and nondiabetic obese Pima Indian subjects. Fasting and postprandial plasma gastrin concentrations were significantly higher (P less than 0.02) in diabetic than in nondiabetic subjects, but gastric acid outputs basally, after an acaloric liquid meal, and in response to betazole were similar in the two groups. Plasma pepsinogen I and pepsinogen II levels were also similar in both groups. A significant negative relation (r = -0.84; P less than 0.01) was found between basal gastrin levels and gastric acid production in nondiabetic Indians, but not in diabetic Pimas. The fractional gastric emptying rate of an acaloric liquid meal was significantly decreased in diabetic Pimas (P less than 0.01); and at least one test showing abnormal vagal function, as estimated by the Valsalva maneuver, heart rate changes between deep expiration and inspiration, and postural hypotension, was found in every diabetic subject. These findings suggest that hypergastrinemia in type II diabetes is not related to hypochlorhydria, but, instead, results from autonomic dysfunction with slow gastric emptying.

Stabilisation of cathepsin E by ATP.

The hydrolysis of 3 distinct substrates by cathepsin E from human red blood cells and gastric mucosa was measured in the presence and absence of physiologically relevant concentrations of ATP. At pH values below about 5.0, the nucleotide was without effect. However, at pH 5.8, whereas cathepsin E was virtually inactive by itself, it was restored to full activity (kcat) by ATP and the non-hydrolysable methylene-ATP analogue. At still higher pH values, kcat progressively diminished but significant levels of cathepsin E activity were readily detectable at pH 7.0. The specificity of this stabilisation effect was examined.

Helicobacter pylori, pepsinogen, and risk for gastric adenocarcinoma.

The objective of this project was to determine the association of Helicobacter pylori infection and serum pepsinogen levels on subsequent risk for gastric adenocarcinoma. This nested case-control study was set in a large health maintenance organization. One hundred thirty-six cases of gastric adenocarcinoma and 136 matched controls without adenocarcinoma from a large cohort that had contributed serum in the 1960's were studied. The presence of IgG against H. pylori had previously been determined by enzyme-linked immunosorbent assay. Serum levels of pepsinogens I and II were ascertained by radioimmunoassay. In a sample of subjects, the presence of antiparietal cell antibodies was determined by immunofluorescent antibody assay (Nichols Laboratory). There were 98 cases of adenocarcinoma of the antrum, body, or fundus (distal cancers) and 30 of the cardia or gastroesophageal junction (proximal cancers). By univariate analysis, H. pylori infection [odds ratio (OR), 3.6; P < 0.001] and serum pepsinogen I < 50 ng/ml (OR = 2.9; P = 0.003) were both associated with development of distal cancer. In multivariate analysis, there was interaction between the two variables; H. pylori in the absence of low pepsinogen I was independently associated with cancer (OR, 2.4; P = 0.04) but low pepsinogen I in the absence of H. pylori infection was not associated with cancer (OR, 0.8; P > 0.5). In combination, however, H. pylori infection and a low pepsinogen I were associated with a marked increase in the risk of developing distal malignancy (OR, 10.0; P = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Helicobacter pylori antibodies in relation to precancerous gastric lesions in a high-risk Chinese population.

Helicobacter pylori infection is a major cause of gastritis and may be a key risk factor for stomach cancer, but its role in the process of gastric carcinogenesis is not well understood. Herein, we examine H. pylori prevalence in relation to demographic and lifestyle factors and to severity of precancerous lesions in an area of China with one of the highest rates of stomach cancer in the world. H. pylori serum IgG antibody positivity was assayed among 2646 adults, ages 35-64, participating in a population-based gastroscopic screening survey in the high-risk area. The prevalence of positivity was evaluated according to gastric histology, environmental and lifestyle variables determined by interviews during the screening, and level of serum pepsinogens. The odds of advanced precancerous lesions (intestinal metaplasia and dysplasia) of the stomach among those with antibody positivity were estimated by logistic regression. Seventy-two % of the population was H. pylori antibody-positive, with nonsignificant variation by sex, age, income, education, family size, and cigarette smoking habits. H. pylori positivity was higher among those who ate sour pancakes, a fermented indigenous staple that is a risk factor for gastric dysplasia and stomach cancer in this population. The prevalence of H. pylori varied most notably, however, with gastric pathology. The percent of H. pylori positivity increased from 55 to 60 to 87% among those with superficial (nonatrophic) gastritis, mild chronic atrophic gastritis, and severe chronic atrophic gastritis, respectively, before falling to 78% among those with intestinal metaplasia or dysplasia. H. pylori antibody positivity also was strongly correlated with serum pepsinogen concentrations, particularly pepsinogen II, but knowledge of H. pylori status did not markedly improve serological identification of advanced precancerous lesions above that provided by pepsinogen ratios alone. The findings suggest that H. pylori infection contributes to the process of gastric carcinogenesis, particularly during the early stages, in this high-risk area.

Inhibition of peptic activity by sucralfate.

It is known that antacids containing aluminum hydroxide inhibit peptic activity by raising intragastric pH and by adsorbing pepsin. Since sucralfate contains aluminum hydroxide moieties, the possibility that this drug might inhibit peptic activity by these same mechanisms was examined. Sucralfate was incubated at a concentration of 10 mg/ml with samples of human gastric juice having pH values between 1.5 and 4 for 30 minutes at 37 degrees C. The proteolytic activity of the supernatant was then determined at a pH of 2.2 against a bovine hemoglobin substrate. When the initial pH of the gastric juice sample was 1.5, sucralfate was converted to a viscous gel and the pH of the incubation mixture rose to 2.9. However, there was no decrease in the peptic activity of the supernatant. In contrast, when the pH of the gastric juice sample was more than 2, the drug remained in suspension, but there was a graded rise in pH to a maximum of 4.1 and a progressive decrease in peptic activity (determined at a pH of 2.2) to a nadir of 65 percent of the control value. However, because peptic activity declines rapidly at a pH of more than 3, peptic activity at the ambient pH of the samples was reduced to only 25 percent of the control value. The results indicate that at pH values of more than 2, sucralfate inhibits peptic activity by both adsorbing pepsin and buffering hydrogen ions.

Immunochemical characterization and cellular localization of pepsinogens in cat and dog.

The antigenic relationships and cellular localization of cat and dog pepsinogens were investigated by electrophoretic analysis, immunodiffusion, immunoelectrophoresis, immunoabsorption, and by immunofluorescence, respectively. Rabbit antiserum to human and hog group I (Pg I) and group II pepsinogens (Pg II) had been previously prepared. Electrophoretic analysis revealed at least eight distinct proteases in extracts of gastric and proximal duodenal mucosa, resistant to alkalinization but destroyed by sequential accidification and neutralization. Rabbit antiserum to Pg I (anti-Pg I) and Pg II (anti-Pg II) produced a single precipitin arc against each extract forming a line of nonidentity. Immunoelectrophoresis of extracts produced a single precipitin arc against anti-Pg I or anti-Pg II. The specificity of the antibodies for the group I or group II pepsinogens was confirmed by immunoabsorption. By immunofluorescnece, both Pg I and Pg II were present in mucous neck and chief cells in fundic mucosa, in the pyloric gland cells in antral mucosa, and Brunner's glands in the proximal duodenum. The results indicate that canine and feline pepsinogens are electrophoretically heterogenous, that canine and feline Pg I share antigenic determinants with each other but not with Pg II, that a similar positive relationship exists for Pg II, and that both Pg I and Pg II are localized to the peptic cell mass, consisting of four types of cells.

Short report: twenty-four-hour hyperpepsinogenaemia in Helicobacter pylori-positive subjects is abolished by eradication of the infection.

Twenty-four-hour plasma pepsinogen I and II concentrations were determined in 8 healthy subjects with antibody to Helicobacter pylori, before and after treatment with tripotassium dicitrato bismuthate, amoxycillin and metronidazole, Therapy was successful in the 5 subjects with active H. pylori infection. In these subjects, median integrated 24-h plasma pepsinogen I and II concentrations significantly decreased from 2288 and 357 micrograms.h/L before treatment, respectively, to 1811 and 171 micrograms.h/L at 4-6 weeks after treatment, and 1643 and 150 micrograms.h/L at 20-24 weeks. By contrast, in the 3 subjects without evidence of active H. pylori infection, pre-treatment plasma pepsinogen I and II concentrations were similar to values found in the H. pylori-infected subjects after successful therapy, and they did not change significantly in response to therapy. H. pylori infection is associated with reversible hyperpepsinogenaemia.

The foveolar cell component of gastric cancer.

M1, a mucin antigen, and cathepsin E, an aspartic proteinase, are both expressed in normal gastric superficial-foveolar epithelial cells. In this study, we determined by immunohistochemical staining the prevalence of these antigens in 316 gastric cancers representative of the main histologic types and stages of the disease. M1 was expressed in 201 cases (64%) and cathepsin E was expressed in 235 cases (75%) of the 313 cases investigated. Both antigens were expressed more commonly in diffuse and mixed cancers than in glandular tumors. M1 was found in 64 of 83 (77%) diffuse cancers and in 48 of 59 (81%) mixed cancers, but in only 74 of 146 (51%) glandular cancers. For cathepsin E, the prevalence was 93% in diffuse cancer, 81% in mixed cancer, and 71% in the 143 glandular cancers examined. Among 25 mucoid tumors, 15 (60%) expressed M1 but only eight (32%) expressed cathepsin E. Overall, 262 (84%) of the tumors expressed at least one of these antigens and of these, 173 (66%) expressed both antigens. No significant difference in the prevalence of M1 or cathepsin E was found between early and advanced cancer or between metastatic and nonmetastatic cancer. The two markers differed in their intracellular localization. In superficial-foveolar cells, M1 immunostaining was concentrated in secretory granules, Golgi complex, and luminal mucous, whereas cathepsin E was found in the endoplasmic reticulum. Moreover, cathepsin E, but not M1, was found in the enterocytes of duodenal villi and, occasionally, in mucopeptic cells. Parallel histochemical and ultrastructural investigations confirmed the occurrence in gastric cancer of foveolar-type cells, manifested by periodic acid-Schiff- and/or alcian blue-reactive mucous granules having a punctate substructure. We conclude that superficial-foveolar cell differentiation is common in gastric cancer and is a major component of this type of tumor. However, pure foveolar cell differentiation is rare. Rather, most gastric cancers consist of cells exhibiting features of foveolar, intestinal, and mucopeptic cell lines.

Fundic atrophic gastritis in an elderly population. Effect on hemoglobin and several serum nutritional indicators.

The ratio of pepsinogen I to pepsinogen II in the circulation decreases progressively with increasing severity of atrophic gastritis of the fundic gland mucosa. Fasting blood was obtained from 359 free-living and institutionalized elderly people (age range, 60 to 99 years). A pepsinogen I/pepsinogen II ratio less than 2.9, indicating atrophic gastritis, was found in 113 (31.5%) subjects. The prevalence of atrophic gastritis increased significantly with advancing age (P less than .05). Within the atrophic gastritis group, 84 had a pepsinogen I level greater than or equal to 20 micrograms/L, indicating mild to moderate atrophic gastritis, and 29 had a pepsinogen I level less than 20 micrograms/L, indicating severe atrophic gastritis or gastric atrophy. A significant increase in the prevalences of elevated serum gastrin levels (P less than .005), low serum vitamin B12 levels (P less than .005), circulating intrinsic factor antibody (P less than .005), and anemia (P less than .025) was observed with stepwise increases in severity of atrophic gastritis. Subjects with atrophic gastritis exhibited a lower mean serum vitamin B12 level (P less than .05) and a higher mean folate level (P less than .05), but no difference was detected in mean hemoglobin levels or serum levels of iron, ferritin, retinol or alpha-tocopherol. It is concluded that serum pepsinogen I and pepsinogen II levels can be used to determine the prevalence and severity of atrophic gastritis, that atrophic gastritis is common in an elderly population, and that atrophic gastritis is associated with vitamin B12 deficiency and anemia. Further, higher folate levels in atrophic gastritis may be related to an accumulation of 5-methyl tetrahydrofolate in serum due to vitamin B12 deficiency and/or greater folate synthesis by the intestinal flora resulting from bacterial overgrowth secondary to hypo- or achlorhydria.

Serum pepsinogen I and II concentrations and IgG antibody to Helicobacter pylori in dyspeptic patients.

AIMS: To investigate the association between histologically confirmed gastritis, carriage of Helicobacter pylori and pepsinogen (PG) I and PG II concentrations. METHODS: Prospective study of 81 dyspeptic patients undergoing upper gastrointestinal endoscopy was made. The extent of gastric mucosal inflammation and the presence of H pylori was determined, and serology to evaluate PG I and II concentrations and IgG titres to H pylori was carried out. RESULTS: The presence of H pylori was strongly correlated with high IgG antibody titres to H pylori and gastritis. Patients who were H pylori positive had significantly higher PG I and PG II concentrations and a significantly lower PG I:PG II ratio than patients who were negative for H pylori. In 13 patients with duodenal ulcer and H pylori positive gastritis serum PG I concentrations were significantly higher than in H pylori positive patients without duodenal ulcer. Significant correlations were found between the age of patients and serum PG II, the PG I:PG II ratio, IgG antibodies to H pylori, the severity of body gastritis and H pylori infection, and between the degree of gastritis in the body of the stomach and the PG II concentration. CONCLUSIONS: Serum PG I and II concentrations, together with a fall in the PG I:PG II ratio, could be used as predictors of H pylori infection as well as serum IgG antibody response to H pylori.

Serum pepsinogens I and II and stomach cancer.

Prospective epidemiologic studies among Hawaiian Japanese men have shown that a serum pepsinogen I (PG I) level below 20 ng/ml is highly specific for extensive intestinal metaplasia of the stomach and for the intestinal type of stomach cancer. The test, however, shows a low level of sensitivity as a predictor of the intestinal type stomach cancer. Since antralization of the corpus, as encountered in Type A atrophic gastritis and late stage Type B gastritis, results in an increase of PG II relative to PG I, we examined the sensitivity and specificity of the PG I/PG II ratio as a predictor of gastric cancer. Using a cut-off point of 2.0 in the ratio to separate subjects at high and low risk for stomach cancer, we found a modest improvement in the level of sensitivity with a small decrease in specificity. Abnormally low PG I levels and PG I/PG II ratios were associated mainly with advanced stages of the intestinal type of cancer and therefore, are not useful screening tests to identify early cases of gastric cancer. The use of the PG I/PG II ratio resulted in a modest improvement in the level of sensitivity with a small decrease in specificity.

Morphology and dynamics of the gastric mucosa in duodenal ulcer patients and their first-degree relatives.

The prevalence of antral and body gastritis was determined in 30 duodenal ulcer patients and in 143 of their first-degree relatives, and compared by conventional mathematical and stochastic analyses with data on gastritis in a representative Finnish population sample. For conventional analysis, the controls for the duodenal ulcer patients and for the duodenal ulcer relatives, were matched for age and sex. For stochastic analysis, the duodenal ulcer patients and their 99 siblings were compared with the total control population of 434 subjects. The prevalence of gastritis affecting mainly the antral mucosa, and both antral and body mucosa to a similar extent was significantly higher in duodenal ulcer patients than in both controls and in relatives. The prevalence of antral and body gastritis in DU relatives and their controls was similar. However, the prevalence of subjects with normal antral and body mucosa was significantly lower. Stochastic analysis revealed more rapid progression of antral gastritis with age in the duodenal ulcer patients than in their siblings or controls and less rapid progression of body gastritis. The overall progression of antral and body gastritis was similar in DU siblings and their controls, but a dichotomy in the mean antral gastritis score of DU sibships was found, indicating high and low antral gastritis liability subgroups. The mean score of DU sibships having a mean age of less than 50 years behaved dynamically like DU patients, while the mean scores of sibships with a higher mean age had a low liability to develop antral gastritis. Most duodenal ulcer siblings who themselves had a duodenal ulcer, ulcer scar or duodenitis were found in the "high antral gastritis liability" subgroup.

Inhibition of peptic aggression by sucralfate. The view from the ulcer crater.

Acid and pepsin have been designated the "aggressive factors" in peptic ulcer because they are essential for ulcer formation and because a reduction in their luminal concentrations is usually followed by ulcer healing. Acid enables peptic aggression by converting pepsinogen to pepsin, by providing the highly acidic pH required for pepsin activity, and by denaturing proteins, thereby increasing their susceptibility to the action of pepsin. Pepsin causes peptic aggression by hydrolyzing peptide linkages which bind together the constituent amino acids of proteins. The first step in this reaction is the formation of a complex between the active site of pepsin and the protein substrate. Sucralfate, which is the basic aluminum salt of sucrose octasulfate, inhibits this step by forming an electrostatic complex with proteins. As such, sucralfate inhibits peptic aggression without decreasing acid-pepsinogen secretion or raising intragastric pH. Because of its affinity for proteins and its insolubility and inherent viscosity in acid, sucralfate forms a physical coating over the ulcer crater. This coating further inhibits peptic aggression by producing a barrier to the diffusion of acid and pepsin. Additionally, the basic aluminum moieties of sucralfate may serve to buffer hydrogen ions as they attempt to permeate the viscous layer. The sum of these effects appears to explain the ability of sucralfate to accelerate the rate of healing of peptic ulcer.

Alpha 1-antitrypsin allo- and phenotypes in gastric and duodenal ulcer.

Serum alpha 1-antitrypsin (A1AT) allo- and phenotypes (including M1, M2 and M3 alleles) were studied in 99 patients with gastric ulcer (GU) and 56 patients with duodenal ulcer (DU) using agarose isoelectric focusing. The results were compared with the A1AT data of a random population sample of similar genetic background (1422 persons). An increase in M2 allotype and M1M2 phenotype as well as a decrease in Z allotype of A1AT was seen in GU in comparison to DU and the random population. There were no particular clinical features which would distinguish patients with M2 allotype from the remainder of the GU group. However, a trend toward elevated serum pepsinogen I and II levels in patients with M2 allotype was seen. When the pepsinogen levels were compared in the GU patient groups with and without M2 allotype, matched between themselves by the state of the gastric mucosa, a statistically significant difference was revealed between pepsinogen II levels in these two groups. No associations were found between DU and any of the A1AT phenotypes.

Serum pepsinogen I and serum gastrin in the screening of severe atrophic corpus gastritis.

The possibilities to screen atrophic corpus gastritis with serum pepsinogen I (S-PGI) and serum gastrin (S-gastrin) concentrations have been studied in 774 subjects: 71 index subjects selected from a general population at random, 353 of their first-degree relatives, 276 first-degree relatives of patients with gastric cancer, 53 patients with pernicious anaemia, and 21 of their relatives. Discrimination function analysis was calculated from members of random and gastric carcinoma families. S-PGI less than 30 ng/ml had a high sensitivity for severe diffuse atrophic corpus gastritis (SDAG) alone (89.5%) and SDAG + severe patchy atrophic corpus gastritis (SPAG) (89.1%). Respective figures for specificity were 91.5% and 94.8%. The discriminatory power of S-PGI less than 30 ng/ml and S-PGI less than 25 ng/ml was of the same order. The sensitivity of low S-PGI decreased sharply in detection of slighter forms of atrophic corpus gastritis. The sensitivity of S-gastrin greater than 100 pmol/l to discriminate SDAG was 57.9% and SDAG+SPAG 58.7%. Respective figures for specificity were 90.2% and 92.2%. Diffuse and patchy atrophic changes behaved similarly regarding S-PGI and S-gastrin mean concentrations. Accordingly, the biopsy specimen with the severest atrophic changes indicates the degree of atrophy, which associates closely with the changes in S-PGI and S-gastrin. In conclusion, severe atrophic (diffuse or patchy) corpus gastritis may be screened from a general population with high sensitivity and specificity by low S-PGI less than 30 ng/ml, whereas an increased level of S-gastrin is too insensitive for this.

Serum pepsinogen I and serum gastrin in the screening of atrophic pangastritis with high risk of gastric cancer.

Serum pepsinogen I (S-PGI) and serum gastrin (S-gastrin) were examined in the screening of three types of atrophic gastritis with inherent high risk of gastric cancer: in 102 cases with severe atrophic corpus gastritis (SACG), in 5 cases with severe atrophic antrum gastritis (SAAG), and in 15 cases with severe atrophic pangastritis (SAPG) (atrophy both in corpus and in antrum) found among 916 subjects from three family series (265 from gastric cancer families, 425 from randomly selected control families and 226 from pernicious anaemia families). There is no way to screen directly atrophic gastritis restricted to the antral mucosa. In pangastritis atrophy of antral glands causes a failure of the hypergastrinemic reaction of achlorhydria. The combination of S-PGI less than 25 micrograms/l + S-gastrin less than 200 pmol/l detected 80.0% of our cases with SAPG, and only 17 subjects of 794 (2.1%) were false positives i.e. who had not advanced atrophic gastritis. The risk of gastric cancer may be significantly higher in SAPG than in SACG. The estimated prevalence of SAPG was 3% in random-family members over 60 years. The combination of S-PGI and S-gastrin is recommended when the cost/benefit ratio in the screening program of gastric cancer is considered and people from a general population are selected for endoscopic studies.

Increase of serum pepsinogen I with age in females with normal gastric mucosa but not in males, possibly due to increase in acid-pepsin secreting area.

The mean pepsinogen I (PG I) level in a Finnish family sample was different in males and females and the difference was statistically significant. After exclusion of subjects with gastritis there remained 67 females and 68 males with morphologically completely normal antral and corpus mucosa. In females there was a significant increase of PG I with advancing age, the regression coefficient being 0.37 and statistically significant (p less than 0.01). In males no such increase was found, and individual cases revealed an almost random distribution with age. A similar increase with age has been noted in gastric acid output in females but not in males. Assuming that there is a linear relationship between PG I levels and the total chief cell mass, the PG I level would be determined by three main variables: thickness of the glandular layer, density of chief cells, and area occupied by chief cells. Of these variables the thickness and chief cell density showed neither in females nor in males any statistically significant increase with age, leaving the area as the variable which would account for the increase of PG I.