A comparative dynamic study of the effectiveness of gastric cytoprotection by vitamin A, De-Nol, sucralfate and ulcer healing by pirenzepine in patients with chronic gastric ulcer (a multiclinical and randomized study)

The gastric cytoprotective effects of vitamin A, De-Nol and sucralfate were compared with the effectiveness of pirenzepine in healing ulcer in patients with chronic gastric ulcer. A total of 100 patients was randomized into different groups: the patients were treated with antacids, vitamin A (3 X 50.000 IU), De-Nol liquid (4 X 5 ml), sucralfate (4 X 1 g) or pirenzepine (3 X 50 mg). The treatment was continued for 4 weeks. At the beginning, 2 and 4 weeks after starting treatment the patients were subjected to endoscopy and the size of the ulcer was measured planimetrically. The ulcer-healing effect of De-Nol liquid was significantly better than that of the antacids (p less than 0.01). Ulcer size was reduced significantly in all groups (p less than 0.01), however, at the end of the study the gastric ulcers were smallest in the De-Nol treated group (p less than 0.001). The dynamics of ulcer healing in the second week was most favourable in the patients receiving vitamin A (p less than 0.01). The present data point to the cytoprotective effects of De-Nol liquid, vitamin A and sucralfate and to their ability of healing chronic gastric ulcers.     

Studies in vitro of the nature and synthesis of the cell wall ofChlamydia trachomatis

The possibility thatChlamydia trachomatis contains peptidoglycan was examined by three methods. Preincubation of chlamydia with enzymes known to cleave peptidoglycan had no adverse effect on the subsequent development. Immunofluorescence studies with antistreptococcal peptidoglycan antisera failed to show any cross reactions with chlamydial antigens. The antichlamydial activity of anti-cell-wall antimicrobials was examined; lactams proved the most active, and cycloserine and bacitracin also showed antichlamydial activity. Alaphosphin, phosphomycin, and vancomycin showed no antichlamydial activity at the concentrations tested.     

A radioimmunoassay for 6-keto- prostaglandin F1α

A radioimmunoassay for 6-keto-prostaglandin F_1α has been developed. The assay is accurate and sensitive but since the antiserum cross-reacts 5–10% with prostaglandins (PGs) of the E and F series, solvent extraction and thin layer chromatography are required fo absolute specifity. The assay has been validated by comparison with a radiochemical assay and by the use of an inhibitor of 6-keto PGF_1α formation, 15-hydroperoxy arachidonic acid. 6-Keto PGF_1α was found to have a low cross reaction with antisera directed against PGE₂, PGF_2α and thromboxane B₂.     

Phase variation: genetic analysis of switching mutants

Site-specific inversion of a controlling element is responsible for flagellar phase transition in Salmonella. When a 900 bp DNA sequence is in one configuration, it allows the expression of the H2 gene, a structural gene which codes for the flagellar antigen. When it is in the opposite configuration, the H2 gene is not expressed. A hybrid λ phage containing the invertible control region and the adjacent H2 gene was constructed, and expression of the H2 gene was shown to be regulated by the orientation of the inversion region. Transposon Tn5 insertion derivatives of this hybrid phage were isolated and λH2::Tn5 mutants defective for inversion (H2 switching) were selected and characterized. Two classes of switching phenotypes were observed among the mutants—those which had slightly reduced frequencies of transition from expression of the H2 gene (H2 on) to nonexpression (H2 off) (intermediate class) and those in which the frequency of transition was reduced at least three orders of magnitude (null class). Physical mapping of the Tn5 insertion sites revealed that in all mutants the insertion was located inside the inversion region. Tn5 insertion sites in the null class of mutants defined a region of DNA including approximately 500 bp which was necessary for inversion. Genetic complementation tests showed that these λH2::Tn5 mutants could invert the H2 gene control element if the 500 bp region was introduced in the trans configuration. It is concluded that a gene is located inside the inversion segment and codes for a protein which is required for the inversion event. Furthermore, the two sites at which the crossover event occurred functioned in a cis configuration and were required for inversion. The presence of a gene which is involved in controlling site-specific recombination events may be a general feature of transposon-like elements.     

Solubility of carbon dioxide in lipid bilayer membranes and organic solvents

Partition coefficients of carbon dioxide into lipid bilayers (liposomes) and organic solvents were measured as a function of temperature. The molar partition coefficient of CO2 into liposomes of egg lecithin at 25 degrees C was 0.95 (ml CO2/ml lipid)/(ml CO2/ml saline). The addition of an equimolar amount of cholesterol to the egg lecithin decreased the partition coefficient by about 25%. The partition coefficients for CO2 into liposomes at 25 degrees C were lower than the partition coefficients into octanol (1.3), hexadecane (1.5) and olive oil (1.7). The results are discussed in terms of the solubility-diffusion model of non-electrolyte transport through lipid bilayer membranes.     

Effect of methabenzthiazuron on growth and nitrogenase activity in Vicia faba

The effects of the herbicide methabenzthiazuron (175 and 220 g ha^-1) on vegetative and reproductive growth, nodulation and nitrogenase activity of Vicia faba were studied in the field under Mediterranean conditions. Nitrogenase activity of excised nodules was estimated using the acetylene reduction assay four times during the developmental period. Leaf area index, dry weight and nitrogen content of the different parts of the plants were measured. Methabenzthiazuron-treated plants showed an increase in nodulation, nitrogenase activity and vegetative growth at early pod fill. Methabenzthiazuron also caused an increase in leaf N content and fruits. These were transient effects found during early and mid pot fill. Nevertheless, plants treated with these sublethal doses of herbicide improved seed production and nitrogen content of seeds at harvest time. The stimulatory effect of methabenzthiazuron on N₂ fixation and vegetative growth seems not be related with the transient stimulatory effect on photosynthetic capacity, also caused by the herbicide, since the stimulatory effect on N₂ fixation was apparent during pod fill, when photosynthetic capacity declined and was not modified by methabenzthiazuron.