Gastro-duodenal mucosal changes associated with low-dose aspirin therapy: a prospective, endoscopic study

OBJECTIVES

The association of low-dose aspirin use and gastro-intestinal bleeding is well described. However, the gastroduodenal mucosal changes associated with low-dose aspirin therapy have not been properly evaluated. We undertook a prospective, endoscopic study to evaluate gastro-duodenal mucosal lesions produced by low-dose aspirin.

METHODS

Forty-seven patients with non-hemorrhagic cerebral infarct or transient ischemic attacks and normal upper gastrointestinal endoscopy were randomized to receive either enteric-coated (n=25) or plain (n=22) aspirin (150 mg/day). Follow-up endoscopy was done at 2, 4 and 8 weeks; gastro-duodenal mucosal lesions, if present, were scored. Forty-seven patients with hemorrhagic infarct who were not treated with aspirin served as controls.

RESULTS

Twenty eight (60%) of 47 patients receiving aspirin had mucosal lesions; stomach alone was the most frequent site (32%), followed by both stomach and duodenum (23%). Frequency of mucosal changes in the stomach at 8 weeks (19%) was significantly lower (p<0.05) than those at 2 weeks (53%) and 4 weeks (55%). Coated (56%) and plain (63.6%) aspirin induced mucosal lesions with similar frequency.

CONCLUSION

Administration of low-dose aspirin, either plain or enteric-coated, induces endoscopic gastro-duodenal mucosal lesions in a large majority of patients. The frequency of damage decreased after 8 weeks of therapy.

Position and sequence requirements for poly(A) length regulation by the poly(A) limiting element

The poly(A)-limiting element (PLE) is a cis-acting sequence that acts to limit poly(A) tail length on pre-mRNA to <20 nt. Functional PLEs are present in a number of genes, underscoring the generality of this control mechanism. The current study sought to define further the position requirements for poly(A) length regulation and the core sequence that comprises a PLE. Increasing the spacing between the PLE and the upstream 3' splice site or between the PLE and the downstream AAUAAA had no effect on poly(A) length control. However, moving the PLE from the terminal exon to either an upstream exon or intron eliminated poly(A) length control. Poly(A) length control was further evaluated using a battery of constructs in which the PLE was maintained in the terminal exon, but where upstream introns were either deleted, modified, or replaced with a polypyrimidine tract. Poly(A) length control was retained in all cases, indicating that the key feature is the presence of the PLE in the terminal exon. A battery of mutations demonstrated the importance of the 5' pyrimidine-rich portion of the element. Finally, UV crosslinking experiments identified an approximately 62-kDa protein in Hela nuclear extract that binds to a wild-type 23-nt PLE RNA oligonucleotides but not to a mutated nonfunctional form of the element.

Polynucleotide phosphorylase is a component of a novel plant poly(A) polymerase

We have isolated cDNA clones encoding a novel RNA-binding protein that is a component of a multisubunit poly(A) polymerase from pea seedlings. The encoded protein bears a significant resemblance to polynucleotide phosphorylases (PNPases) from bacteria and chloroplasts. More significantly, this RNA-binding protein is able to degrade RNAs with the resultant production of nucleotide diphosphates, and it can add extended polyadenylate tracts to RNAs using ADP as a donor for adenylate moieties. These activities are characteristic of PNPase. Antibodies raised against the cloned protein simultaneously immunoprecipitate both poly(A) polymerase and PNPase activity. We conclude from these studies that PNPase is the RNA-binding cofactor for this poly(A) polymerase and is an integral player in the reaction catalyzed by this enzyme. The identification of this RNA-binding protein as PNPase, which is a chloroplast-localized enzyme known to be involved in mRNA 3'-end determination and turnover (Hayes, R., Kudla, J., Schuster, G., Gabay, L., Maliga, P., and Gruissem, W. (1996) EMBO J. 15, 1132-1141), raises interesting questions regarding the subcellular location of the poly(A) polymerase under study. We have reexamined this issue, and we find that this enzyme can be detected in chloroplast extracts. The involvement of PNPase in polyadenylation in vitro provides a biochemical rationale for the link between chloroplast RNA polyadenylation and RNA turnover which has been noted by others (Lisitsky, I., Klaff, P., and Schuster, G. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 13398-13403).

A plant poly(A) polymerase requires a novel RNA-binding protein for activity

We have purified a novel factor (PAP-III) that is a component of a multisubunit poly(A) polymerase from pea seedlings. This factor consists of one or more polypeptides with molecular masses of about 105 kDa and of a population of associated RNAs that can serve as substrates for polyadenylation. When these RNAs are separated from the 105-kDa polypeptides, polyadenylation becomes dependent upon exogenously added RNA. This RNA-dependent activity does not require the presence of a polyadenylation signal in the substrate, indicating that the activity under study is a nonspecific polyadenylation activity. One or more of the 105-kDa polypeptides could be cross-linked to the products of polyadenylation labeled with [alpha-32P]ATP and to exogenously added labeled RNAs. Cross-linking of the 105-kDa polypeptides to the products of polyadenylation was not affected by the presence of exogenously added competitors, whereas cross-linking to exogenous RNAs was diminished by excesses of RNA homopolymers. Exogenous RNAs could be polyadenylated by the combination of PAP-I + PAP-III, and this activity was diminished if the binding of the exogenous RNAs to PAP-III was prevented. We conclude from these studies that PAP-III is an RNA binding protein, that polyadenylation by the poly(A) polymerase occurs while the substrate RNAs are associated with this protein, and that the pea poly(A) polymerase can only polyadenylate those RNAs that are associated with PAP-III.

Influence of dietary restriction and soyabean supplementation on the growth of a murine lymphoma and host immune function

A comparative study was made to reveal the influence of caloric restriction with or without soyabean in the diet on the growth of a murine lymphoma, host survival, serum profile of vitamin A and E and immune status of the host. Caloric restriction delayed and inhibited tumour growth and improved host survival; inclusion of soyabean during restriction enhanced this effect. Dietary restriction both in the absence and presence of soyabean improved the proliferative response of peripheral blood lymphocytes. This was accompanied by increased cytolytic activity of peritoneal macrophages and elevation in serum immunoglobulins (IgG and IgM). Levels of vitamins A and E, which is found to be low in tumour bearing animals, decreased further when maintained in the restricted diet without soyabean, but was raised to normal levels following addition of soyabean in the diet. These observations imply that tumour growth is arrested possibly by insufficient nutrition available due to dietary restriction, for actively proliferating tumour cells and by improvement in host immune mechanism in the presence of soyabean in the diet.

Experimental evaluation of preventive and therapeutic potentials of lysozyme

Therapeutic efficacy and preventive role of egg white lysozyme was evaluated in three types of murine ascitic tumours, namely sarcoma 180, Ehrlich's carcinoma, and Dalton's lymphoma. Lysozyme treatment produced regression of tumour growth and improved the life expectancy of the host. Growth of tumour cells treated in vitro with lysozyme prior to transplantation was also affected. In addition, lysozyme was found to have a preventive effect when administered to normal mice. The antitumour activity, therapeutic and preventive, of lysozyme seems to be due to its action on the tumour cell surface as well as on the host-mediated immune response.

Chronic arsenic toxicity from drinking tubewell water in rural West Bengal

Hepatic damage caused by chronic exposure to arsenic has been frequently described. Here we report on 13 patients from West Bengal, India, who consumed large amounts of arsenic in drinking water. An epidemiological investigation of the study area showed evidence of chronic arsenical dermatosis and hepatomegaly in 62 (92.5%) of 67 members of families who drank contaminated water (arsenic level, 0.2-2 mg/l). In contrast, only six (6.25%) of 96 persons from the same area who drank safe water (arsenic level, <0.05 mg/l) had non-specific hepatomegaly, while none had skin lesions. Hepatomegaly occurred in all the 13 patients who were studied in detail, although five had splenomegaly. Biopsy of samples of liver from these patients revealed various degrees of fibrosis and expansion of the portal zone that resembled non-cirrhotic portal fibrosis (NCPF).

Trace elements in the sera of leprosy spectrum

Serum zinc, copper, calcium and magnesium levels were estimated by atomic absorption spectrophotometry in 56 leprosy patients comprising 14 BT, 12 BB, 11 BL and 19 LL. These findings were evaluated in comparison to 42 normal subjects serving as controls. A significant elevation of serum copper was recorded while reduction in zinc, calcium and magnesium was noted throughout the leprosy spectrum. The findings of our study are of considerable importance and need to be taken note of in the light of delineating these alterations to be the cause or effect of the disease.

Levels of glycolytic enzymes in the red blood cells of Australian Aborigines

Blood samples wer collected from three populations of full-blood Aborigines, and twelve different enzymes were assayed in red blood cells. These results were compared with those of Caucasian controls. In the majority of enzymes studied significant differences were observed between the Aboriginal populations and also between individual Aboriginal populations and the Caucasian controls.

Effect of other drugs and chemicals on the degradation of aspirin in vitro: possible extrapolation to in vivo metabolism of aspirin

To assess the possible influence of other drugs and chemicals on the metabolic degradation of aspirin in man, their effect on the serum aspirin esterase activity was determined in vitro. The activation or inhibition of the enzyme as observed with these compounds suggest the possibility that simultaneous ingestion of these drugs with aspirin may influence the pharmacology and toxicity of the analgesic.

Serum aspirin esterase activity in women with habitual aspirin intake

A method for the determination of aspirin esterase activity in serum is described. Sera from 59 pregnant women who were habitual aspirin users were found to have a mean enzyme activity value statistically lower than those of 68 non-pregnant women controls or of 12 pregnant women controls who were either occasional users of the drug or were non-users. The distribution of enzyme activity in the experimental group was also significantly different from that of the control group. It is postulated that the low enzyme activity may further aggravate the injurious effects of high intake of aspirin.

Galactose metabolism in relation to cataract formation in marsupials

Erythrocytic galactokinase and/or galactose-1-phosphate uridyl transferase activity were low in many species of marsupials. However, cataract formation was observed only in pouch-young members of these species when reared on cow's milk. The galactose tolerance of young kangaroos was found to be greatly impaired, but improved rapidly and markedly at the stage of which the definitive structure of the ruminant type of stomach as in adults is formed. The combination of high absorption of galactose and low levels of galactokinase and/or transferase thus appears to determine the predisposition of pouch-young marsupials to galactose cataractogenesis.

Differential immune response to attenuated rubella virus vaccine

Serum samples collected from 18 volunteers 1, 2, and 3 months after vaccination with Cendehill strain of attenuated rubella virus vaccine were fractionated on a Sephadex G-200 column to test for immunoglobulin M (IgM) antibody. Seventeen of the 18 had demonstrable IgM antibody in serum collected 1 month postvaccination whereas only 5 and 3 had IgM antibody 2 and 3 months, respectively, post-inoculation. The geometric mean titers of hemagglutination-inhibiting antibody in the 19S fraction were 38, 7, and 6 at 1, 2, and 3 months after vaccination, whereas the corresponding 7S titers were 29, 53, and 57, respectively. Four other seronegative volunteers vaccinated with Cendevax were tested serially for total antibody only in whole blood obtained by finger pricks. Three of them showed appearance of antibody between 14 and 17 days and one between 17 and 21 days. It appears that vaccine-induced immune response is similar to natural infection especially with regard to the time of appearance of antibody and the relative proportions of IgM and IgG antibody thus produced.

Determination of rubella hemagglutination-inhibiting antibody in whole blood

A technique is described for determination of rubella hemagglutination-inhibiting antibody in only 50 to 100 muliters of whole blood.

Single-sample diagnosis of recent rubella by fractionation of antibody on Sephadex G-200 column

To facilitate the diagnosis of recent rubella infection, rubella haemagglutination inhibiting antibody has been determined in four fractions obtained by Sephadex G-200 gel filtration of samples of serum. All the 21 samples collected at the convalescent stage of the disease had varying proportions of haemagglutination inhibiting antibody in fraction 1, representing the major portion of IgM antibody whereas all but three out of 22 sera from persons with no history of recent rubella had negative titres in this fraction. The haemagglutination inhibiting titres in the three positive sera in the second group was very low as compared to the other fractions. Fractionation of sera on a Sephadex G-200 column coupled with the rubella haemagglutination inhibition test can, therefore, be used to diagnose recent rubella infection.

Use of a new buffer system with formalinized sheep erythrocytes in the rubella hemagglutination-inhibition test

The increased sensitivity and improved agglutination and settling patterns of formalinized sheep erythrocytes in a new buffer, HEPES (N-2-hydroxyethylpiperazine N'-2'-ethanesulfonic acid), make this system more suitable for use in the rubella hemagglutination-inhibition test.

Use of formalinized sheep erythrocytes in the rubella hemagglutination-inhibition test

Rubella antibody determination by the hemagglutination-inhibition test was effectively simplified by substitution of formalinized sheep red blood cells for avian erythrocytes.