The endotoxin of Helicobacter pylori is a modulator of host-dependent gastritis

Atrophic gastritis caused by Helicobacter pylori is the precursor lesion in the development of intestinal-type gastric adenocarcinoma. In animal models, atrophic gastritis induced by Helicobacter felis has been shown to be host dependent, developing in some mouse strains and not in others. The lipopolysaccharide (LPS) of H. pylori has been suggested to play a role in the induction of gastritis. The goal of this study was to compare the inflammation induced by long-term infection of the C3H/He and the C3H/HeJ strains of mice with H. felis. C3H/HeJ mice are unresponsive to LPS. Six months after infection, severe atrophic gastritis had developed in the body mucosae of all infected C3H/He mice, with replacement of parietal and chief cells. Atrophy was associated with a loss of the H. felis from the antral mucosa. In contrast, no atrophy was seen in the infected C3H/HeJ non-LPS responder animals, and heavy colonization of the antrum remained. There were no significant differences between both the quantitative and qualitative serum immunoglobulin G (IgG) and salivary IgA levels in both strains of mice. The main difference between the two strains of long-term-infected mice was a lack of macrophage infiltration in the lamina propria. Immunization induced good protective immunity to challenge with viable H. felis. Helicobacter-induced, host-dependent gastritis is likely to be cell mediated. The C3H/He and C3H/HeJ mouse model provides an excellent opportunity to investigate the cellular basis of atrophic gastritis.

[Critical review on the WHO/IARC report regarding carcinogenicity of Helicobacter pylori]

Helicobacter pylori has been defined as a "definite carcinogen" at the WHO/IARC meeting in 1994. H. pylori causes histological gastritis. Long-lasting infection may induce atrophic gastritis, which is considered to be the first step in the gastritis-metaplasia-carcinoma sequence of the stomach. In a pooled analysis of the three prospective epidemiological studies, the relative risk for developing gastric cancer with H. pylori infection was 3.8, which was statistically significant. Thus, it was concluded that there was sufficient evidence in humans for the carcinogenicity of infection with H. pylori. However, there was no evidence experimentally for the carcinogenicity of infection with H. pylori. Further study is necessary to elucidate the role of H. pylori in gastric carcinogenesis.

Atrophic gastric changes in both Helicobacter felis and Helicobacter pylori infected mice are host dependent and separate from antral gastritis

BACKGROUND/AIMS

The role of host factors has been neglected in studies of the pathogenesis of Helicobacter associated disease. The aim of this study was to assess the response of different mouse strains to infection with a single strain of Helicobacter felis.

METHOD

Six strains of inbred mice were infected with the identical H felis culture and were killed at one month, two months, and six months after infection to assess histopathological changes. In addition, two strains of mice were infected with a mouse adapted strain of H pylori and examined at six months after infection.

RESULTS

In SJL, C3H/He, DBA/2, and C57BL/6 infected mice, severe to moderate chronic active gastritis was observed only in the body of the stomach, which increased in severity over time with specialised cells in the body glands being replaced. As the severity of this damage in the body increased and atrophic changes were seen, the level of bacterial colonisation of the antrum decreased. In contrast, in BALB/c and CBA mice, there was only mild gastritis in the antrum, no remarkable changes were detected in their body mucosa, and no atrophy was seen over time. In both these strains of mice, heavy bacterial colonisation was seen, which tended to increase over the period of the experiment. Of particular importance in this experiment was that bacterial colonisation was mainly restricted to the antrum yet the atrophy, when present, was only observed in the body of the stomach. H pylori infected C3H/He mice showed moderate colonisation of the antrum, which persisted up to six months with little development of atrophy. In contrast, H pylori in C57BL/6 mice showed excellent colonisation of the antrum at two months but six months after infection there was moderate to severe body atrophy, which was associated with a loss of bacteria from the antrum.

CONCLUSIONS

These findings challenge current concepts of the development of Helicobacter induced atrophy in that active chronic gastritis of antrum or the body mucosa, or both, is not a prerequisite. They also suggest an autoimmune basis for the pathology although no autoantibody or antibody to the H+/K+ ATPase was detected. Loss of infecting helicobacters from the stomach together with development of an atrophic gastritis in the body of the stomach is similar to the pattern found in certain H pylori infected human subjects.

Relationship between ascorbyl radical intensity and apoptosis-inducing activity

Ascorbic acid and its related compounds were compared for their ascorbyl radical intensity and apoptosis-inducing activity. Sodium L-ascorbate, L-ascorbic acid, D-isoascorbic acid, sodium 6-beta-O-galactosyl-L-ascorbate and sodium 5,6-benzylidene-L-ascorbate, at the concentration of 1-10 mM, induced apoptotic cell death characterized by cell shrinkage, nuclear fragmentation and internucleosomal DNA cleavage in human promyelocytic leukemic HL-60 cells. On the other hand, L-ascorbic acid-2-phosphate magnesium salt and L-ascorbic acid 2-sulfate did not induce any of these apoptosis-associated characteristics. ESR measurements revealed that all the active compounds were progressively degraded, producing the ascorbyl radical (g = 2.0064, hfc = 0.17 mT) in culture medium, whereas the inactive compounds were stable and did not produce the ascorbyl radical. Cytotoxicity began to appear when the radical intensity exceeded a certain threshold level. In the presence of N-acetyl-L-cysteine, both ascorbyl radical intensity and apoptosis-inducing activity were significantly reduced. These data suggest the possible involvement of the ascorbyl radical in apoptosis induction by ascorbic acid-related compounds. Exposure of HL-60 cells to ascorbic acid or its active derivatives resulted in the rapid elevation of intracellular Ca2+ concentration, which might serve as the initial signal leading to the cell death pathway.

[Helicobacter pylori and gastric cancer]

H. pylori has been included as a definite biological carcinogen by WHO/ IARC. H. pylori is thought to play a role in the gastritis-metaplasia-carcinoma sequence by inducing atrophic gastritis. Clinical and epidemiological studies have shown a close association between H. pylori infection and gastric cancer. Yet, experimental evidence is equivocal. Epidemiological evidence also suggests that there are significant variable(s) other than H. pylori infection in gastric carcinogenesis. Clearly many questions regarding the role of H. pylori in gastric carcinogenesis have been left for further study. The authors have summarized these aspects together with their experimental results.

Induction of DNA fragmentation by tannin- and lignin-related substances

A variety of tannin and lignin-related compounds were compared for their ability to induce nucleosome-sized DNA fragmentation (a biochemical hallmark of apoptosis), using agarose gel electrophoresis and a fluorescence activated cell sorter. Monomeric, dimeric, trimeric and tetrameric hydrolysable tannins induced nucleosome-sized DNA fragmentation in HL-60 cells, more potently than condensed tannins. The highest activity was detected in gallic acid, a component unit of tannins. Natural lignified materials, except for caffeic acid and its dehydrogenation polymer, showed much weaker activity. Protein-bound polysaccharide (PSK) was inactive. Gallic acid induced DNA fragmentation in four human myelogenous leukaemic cell lines, but not in human T-cell leukaemia and erythroleukaemia cell lines. Ca2+ depletion from the culture medium slightly, but significantly, reduced the apoptosis-inducing activity of gallic acid, but did not significantly affect that of tannic acid or caffeic acid. After treatment with gallic acid, intracellular Ca2+ concentration was significantly elevated. The apoptosis-inducing activity of polyphenols may further emphasize their medicinal efficacy.

Hypochlorite scavenging activity of polyphenols

Chemiluminescence, generated by the mixture of sodium hypochlorite solution and luminol, was completely eliminated by polyphenols, such as natural lignins, phenylpropenoid monomers and polymers, and epigallocatechin gallate. On the other hand, hypochlorite scavenging activity of polysaccharides, such as PSK (Krestin) and Schizophyllan, was relatively weak. Human myelogenous leukemic cell lines (HL-60, ML-1) showed higher production of active oxygen(s) (detected by luminol chemiluminescence) and iodination capacity, than six other cultured cell lines. Since lignin did not completely eliminate the active oxygen production by HL-60 cells, possible stimulation of hypochlorite production by lignin was suggested.

Endonuclease activity and induction of DNA fragmentation in human myelogenous leukemic cell lines

When four human myelogenous leukemic cell lines (HL-60, ML-1, U-937, THP-1) were exposed to either ascorbic acid, hydrogen peroxide, etoposide, tumor necrosis factor, hyperthermia or UV irradiation, their growth inhibition and oligonucleosome-size DNA fragmentation were induced. Non-myelogenous leukemic cell lines (MOLT-4, K-562) were similarly sensitive to ascorbic acid and hydrogen peroxide, but relatively resistant to etoposide, TNF, hyperthermia and UV irradiation. Furthermore, these treatments except for UV irradiation, did not induce any apparent DNA fragmentation in MOLT-4 and K-562 cells. An autodigestion experiment revealed that all of these six cell lines contained divalent cation-independent endonuclease activity as a major endonuclease. The ability of this endonuclease to produce oligonucleosome-size DNA fragmentation was stimulated at acidic, but not at neutral pH. Since this enzyme activity was not detected in the lysosomal enzyme-free nuclei, prepared from all six cell lines, the cytoplasmic localization of this enzyme was suggested. The results suggest that the endonuclease activity might be differently regulated between myelogenous and non-myelogenous leukemic cell lines.

[Advances in the experimental analysis of behavior: issues of choice behavior, comparative cognition, and human language]

As the opportunity to contact with related areas has increased, the study of of the experimental analysis of behavior has experienced revolutionary changes. Some of the most active and important areas-studies of choice, comparative cognition, and human language--are reviewed to acquaint readers. Studies of CHOICE have linked to the molar theories of behavioral economics and behavioral ecology, which promoted research of choice by animals under uncertainty conditions. Further approach has been made to integrate the molar and molecular analyses on the basis of the ideas of behavior dynamics. COMPARATIVE COGNITION is a part of a larger field including cognitive science, behavioral neuroscience, and biological science. Recent developments, aided with a comparative perspective, made significant contributions to our understanding of the phylogeny and ontogeny of cognition. Advances in analysis of human behavior provided tools to study behavioral aspects of semantics, syntax, and pragmatics of HUMAN LANGUAGE. Using the paradigm of stimulus equivalence, the emergence of stimulus relations, stimulus-stimulus networks, hierarchical structure of verbal behavior, and other language-related behaviors have been investigated.

Structure and chromosomal locus of the mouse gene encoding a cerebellar Purkinje cell-specific helix-loop-helix factor Hes-3

HES-3 is a cerebellar Purkinje cell-specific helix-loop-helix factor structurally related to the products of the Drosophila hairy and Enhancer of split genes. Here, we report the nucleotide sequence and chromosomal locus of the mouse Hes-3 gene. This gene consists of four exons and the exon-intron boundaries are well conserved when compared with those of the mouse Hes-1 and Drosophila hairy genes. Southern blot and interspecies backcross analyses show that the mouse Hes-3 gene is a single-copy gene and is located around position 80 on chromosome 4. Further analysis indicates that this locus is close to the Hes-5 locus, which is different from the Hes-1 locus (position 26 on chromosome 16). These results suggest that the Hes-3 and Hes-5 genes may be clustered on chromosome 4 while the Hes-1 gene is not.

Induction of DNA fragmentation in human myelogenous leukemic cell lines by sodium 5,6-benzylidene-L-ascorbate and its related compounds

High-performance liquid chromatography revealed that sodium 5,6-benzylidene-L-ascorbate (SBA), dissolved in distilled water, was gradually decomposed into ascorbic acid and benzaldehyde. Among these three compounds, ascorbic acid showed the most potent cytotoxic activity. The cytotoxic activity of each compound was significantly reduced during degradation in culture medium. Agarose gel electrophoresis and fluorometric determination of DNA revealed that ascorbic acid, as well as SBA, induced DNA fragmentation into nucleosomal oligomers in human myelogenous leukemic cell lines, but not in freshly isolated human peripheral blood cells. The results suggest that antitumor activity of SBA might be at least in part mediated by the action of ascorbic acid, a degradation product of SBA.

[Frequency of food intake of dentulous and complete denture wearers]

The study was carried out on 1466 subjects, whose ages ranged from 20 to 80 years of age, of whom 1181 were dentulous and 285 were complete dentures. We studied the frequency with which the 1466 cases partook of food. The results were as follows: 1) Ingested foods were classified into 10 groups along with the frequency with which they were ingested on a yearly seasonal basis. Food groups were classified as follows: vegetables, grain, sea food, beans, meat, seaweed, potatoes, fruits, etc. 2) The Ingested foods of the dentulous group were similar to those of the complete denture wearers. 3) In all age groups the foods most ingested were: steamed rice, wakame, tofu, bread, scallions, Japanese omelette, and tomatoes. 4) The younger subjects (20 to 39 years) statistically ate significantly lower amounts of steamed rice than did the older age groups. 5) The younger generation ate more meat, while the older groups ate more sea food.

Phospholipid metabolism in bile duct-ligated rat plasma and erythrocytes

Incorporation of [32P]orthophosphate into phosphatidylcholine, lysophosphatidylcholine and molecular species of phosphatidylcholine in vivo was observed in liver, plasma and erythrocytes of bile duct-ligated or sham-operated rats. Both the amount and radioactivity of dienoic species of phosphatidylcholine in all tissues examined increased in bile duct-ligated rats as compared to sham-operated rats. The experiments in vivo and in vitro showed that the ratio of lysophosphatidylcholine to phosphatidylcholine transferred to erythrocytes from plasma in sham-operated rats was much higher than that in bile duct-ligated rats. It is suggested that one of the mechanisms by which abnormal erythrocytes appear might be explained by the facilitated and direct transfer of phosphatidylcholine, which is caused by the interaction of erythrocytes with bile acid in bile duct-ligated rat plasma.

A fluorimetric determination of the activity of glycolipid transfer protein and some properties of the protein purified from pig brain

The fluorimetric method of Correa-Freire et al. (Correa-Freire, M.C., Barenholz, Y. and Thompson, T.E. (1982) Biochemistry 21, 1244-1248) to measure glucosylceramide transfer between phospholipid bilayers has been applied to the determination of the activity of glycolipid transfer protein purified from pig brain. The transfer of pyrene-labeled galactosylceramide (PyrGalCer) from donor to acceptor vesicles was measured by a decrease in the intensity ratio of eximer (E) to excited monomer (M). A sensitive determination of the glycolipid transfer activity is possible by the fluorimetric method without separation of the donor and acceptor vesicles. The newly developed fluorimetric assay of glycolipid transfer protein was used to study the effects of N-ethylmaleimide, HgCl2 and sugars on the transfer activity. The treatment with N-ethylmaleimide inactivated the activity to about 40%. The activity was almost completely inactivated by the treatment with HgCl2. Monosaccharides and methyl-alpha-D-glucoside had no inhibitory effect on the transfer activity. A marked and immediate drop of the E/M ratio was observed by the addition of glycolipid transfer protein to vesicles containing PyrGalCer at a protein-to-PyrGalCer molar ratio of 1.56:1. The result suggests a complex formation of glycolipid transfer protein with PyrGalCer.

Experimental biliary obstruction of rat. Initial changes in the structure and lipid content of erythrocytes

The bile duct was ligated and the resulting changes in the plasma and erythrocyte lipid composition and in the shape of erythrocytes were observed. Electron microscopy at 8th hour after ligation revealed the appearance of spur cells, and on the 7th day target cells began to be observed. The appearance of spur cells was considered to be a reflection of abrupt increases in bile acid and bilirubin levels in the plasma. The conversion of spur cells to target cells which was observed was accompanied by increased levels of cholesterol and phosphatidylcholine in the erythrocytes. Plasma phosphatidylcholine and cholesterol levels were increased immediately after the commencement of ligation. On the other hand, erythrocyte phosphatidylcholine and cholesterol levels only gradually increased when compared to those in plasma, and the maximum value was observed from the 5th to the 7th day. The fatty acid composition of the increased plasma phosphatidylcholine after ligation resembled that of phosphatidylcholine in bile. On the other hand, the fatty acid composition of erythrocyte phosphatidylcholine changed remarkably between the 1st and 3rd days after bile duct ligation. These changes were also reflected by those of phosphatidylcholine in bile. These results led to the conclusion that the appearance of target cells observed in the present study was due to the accumulation of erythrocyte lipids which derived from bile. This is the first report on experimentally induced target cells and the mechanism for their appearance that seems applicable for humans.

Ecto-5'-nucleotidase does not catalyze vectorial production of adenosine in the perfused rat liver

From the results obtained in perfused rat hearts, Frick and Lowenstein proposed that ecto-5'-nucleotidase catalyzes a vectorial reaction in which AMP hydrolysis is accompanied by transfer of adenosine across the cell membrane (Frick, G.P., and Lowenstein, J.M. (1978) J. Biol. Chem. 253, 1240-1244). We have examined by the use of perfused rat livers, the uptake mechanism of adenosine generated from AMP by ecto-5'-nucleotidase. Recirculating perfusion of rat livers was performed with a buffered saline containing [2-3H]AMP at an initial concentration of 5 microM. One-half of the [2-3H] AMP was dephosphorylated by 0.8 min of perfusion; less than 13% of the radioactivity of hydrolyzed [2-3H] AMP was located in [2-3H]adenosine plus [2-3H]inosine appearing in the perfusate. Addition of 6-[(4-nitrobenzyl)thio]-guanosine, an inhibitor of the nucleoside transport system, at 120 microM to the perfusate caused a 3.9-fold increase in the amount of the [2-3H]AMP-derived 3H-nucleosides appearing in the perfusate. Moreover, in a perfusion in which uridine was added to the perfusate at 2.6 mM to compete with the [2-3H] AMP-derived [2-3H]adenosine for the nucleoside transport system, more than 87% of the radioactivity of hydrolyzed [2-3H]AMP was located in [2-3H]adenosine appearing in the perfusate; the result indicates that the uridine added to the perfusate efficiently trapped the [2-3H]adenosine formed from [2-3H]AMP. These results support an uptake mechanism of the AMP-derived adenosine in which the adenosine formed by ecto-5'-nucleotidase in the blood-sinusoidal plasma membrane of hepatocytes, is taken up by the nucleoside transport system located at the plasma membrane side by side with ecto-5'-nucleotidase. The results therefore indicate that the ecto-5'-nucleotidase of hepatocytes does not catalyze vectorial production of adenosine, in contrast to the previous report on perfused rat hearts.

Effect of prostaglandin E1 and polyphloretin phosphate on hemolysis of human erythrocytes

Prostaglandin E1 was found to reduce the hemolysis rate induced by various factors, such as frequent shakings, treatment with hog pancreatic phospholipase A2, the addition of active oxygens generated by a xanthine oxidase system, and the addition of a prostaglandin antagonist, polyphloretin phosphate (PPP). Prostaglandin E1 was found to act on the erythrocytes in such a way as to cause the phospholipids in the membrane to become more compactly arranged thus becoming less susceptible to the attack of hemolytic reagents. It was observed that the extents of hemolysis were different between erythrocytes from males and females and furthermore, it was shown that prostaglandin E1 clearly reduced the rate of hemolysis of erythrocytes from males, while, in females, the effects of prostaglandin E1 were less than those in erythrocytes from males.