Iranian Biomedical Journal
Volume:5 Issue: 4, Oct 2001

Helicobacter pylori infection is among the most prevalent infections in the world involving more than half the adult population. H. pylori infection results in active chronic gastritis, peptic ulcers and enhances the risk of gastric malignancies. It is of utmost importance to prevent H. pylori infection particularly in highly prevalent countries including Iran. The urease holoenzyme produced by the entire Helicobacter species is essential for their virulence such that urease-negative mutant strains are unable to colonize the gastric lumen of various animal models. Furthermore, urease has shown to be an effective immunogen. Despite the fact that urease is considered among the very conserved genes of this pathogen, our molecular studies have shown that H. pylori strains obtained from Iranian patients vary considerably from those of other populations particularly the Western strains. Therefore, in order to develop a putative vaccine against H. pylori infection for the Iranian population, we have PCR-amplified and cloned the A and B subunits of this gene from a local H. pylori strain. Following identity confirmation, it was subcloned into a pET expression vector under the control of T7 promoter. The resulting plasmid was transformed into E. coli BL21-DE3 strain. Laboratory scale culture of the resulting transformants was analyzed by SDS-PAGE and Western blotting techniques. This analysis confirmed the expression of the A and B subunit of H. pylori urease protein up to 25% of the total cellular protein.

The biodegradation of secondary amines is particularly important due to their propensity for conversion either chemically or microbiologically to N-nitrosamines which are potent carcinogens. In this research, a weak Gram-positive organism was isolated from river and identified as Mycobacterium. This Mycobacterium grows slowly and effectively utilizes piperazine as the sole source of organic, carbon, nitrogen and energy. Also, it has one 60-kb plasmid on gel agarose which involves in piperazine degradation however the mutant strain which were obtained by subculturing in nutrient broth (pip-) has lost this plasmid. This might suggest that the ability to degrade piperazine are plasmid encoded.

The restriction enzyme Ava II detects the base change of the intervening sequence II (IVS II) which is used as one of the markers of β-globin gene polymorphism. This study was conducted to determine the frequency of the Ava II site on the β-globin gene among normal people and patients with sickle cell syndrome (SCS) in Iran. DNA fragments containing the IVS II region of the β-globin gene from 30 patients with sickle cell anemia and 30 normal individuals were amplified using PCR technique. The amplified DNA of various subjects was digested with the Ava II enzyme and the products were examined by electrophoresis on agarose gel. The Ava II site was present in all 60 chromosomes of the patients while it was present with a frequency of 78% in the chromosomes of the normal individuals. The results were compared with those of Afro-American blacks, Italian and some Indian populations. Our results demonstrate the association of the Ava II site in the β-globin gene with sickle cell mutation in the Iranian population.

Lipophilic yeast of the genus Malassezia (Pityrosporum) belongs to the normal flora of human skin and many warm-blooded animals. These fungi can produce a diverse range of diseases that the best known and most frequent of them is pityriasis versicolor, a chronic recurrent skin disease occurring primarily in tropical regions. The genus Malassezia has been recently enlarged to include seven distinct species. Very little information has been documented about identifying Malassezia species in Iran. This survey was undertaken to present a practical approach for differentiation of all Malassezia yeasts isolated from clinical materials of patients with pityriasis versicolor for the first time in Iran. The presence of the disease was confirmed on the basis of the observation of budding yeast cells and short curved hyphae in skin specimens by direct microscopy. Malassezia yeasts were isolated after culturing the samples on modified Dixon (mDixon) agar. A combination of different characteristics includes yeast cell morphology, ability to growth on sabouraud dextrose agar, catalase test and ability to utilize individual Tweens (20, 40, 60, 80) were used for identification of species. In general, 138 patients with pityriasis versicolor includes 52.2% male and 47.8% female were identified. Direct microscopy and culture results were positive in 94.4% and 63% of the patients, respectively. Totally, 91 isolates of Malassezia belonging to four different species, M. globosa (66 isolates), M. furfur (18 isolates), M. obtusa (5 isolates) and M. sympodialis (2 isolates) were identified.

The focus of this study was to determine if early detection of mutant p53 accumulation may be an early indicator of tumor aggressiveness and transformation to invasive breast cancer. For this purpose, the p53 content of 100 human breast biopsies classified as ductal carcinoma (DCIS), was evaluated by immunohistochemical method. All specimens were microscopically classified into histologic types of DCIS and nuclear grade. From this population, 15 specimens were immunopositive and six of them were converted to more invasive form. Most immunopositive specimens were classified as mixed histologic types. No relationship between nuclear grade and different histologic types of DCIS was noticed. Preliminary data indicated that the presence of immunopositive p53 may be a valid predictive indicator of the prognosis of individuals with DCIS and transformation to invasive breast cancer.

Atropine has been used to block cholinergic neurotransmission in basic research. Large doses of atropine cause vasodilation of the blood vessels in the skin. This effect is apparently unconnected with the antimuscarinic activity of atropine and seems to be due to a direct action on the blood vessels. It has been suggested that atropine blocks muscarinic receptors at low doses and it induces the release of endothelium derived relaxing factor (EDRF) at large doses. This study examined the effects of atropine on isolated rat pulmonary artery rings with or without endothelium intact in the absence and presence of nitric oxide synthase inhibitors, N-omega nitro-L-arginine methyl ester (L-NAME) or N-omega nitro-L-arginine (L-NOARG) that precontracted with phenylephrine (PHE), 5-hydroxy-tryptamine (5-HT) or KCl. Atropine (1 nM) blocked the vasorelaxant effect of acethylcholine (1 µM) in pulmonary artery rings precontracted with PHE (100 nM). Atropine (10 nM-5 μM) also produced concentration dependent relaxation in these rings precontracted with PHE or 5-HT, but did not relax rings precontracted with KCl. The vasorelaxant effects of atropine were partially inhibited by the mechanical remove of endothelium or pretreatment the rings with L-NAME or L-NOARG, although they were not statistically significant. These results suggest that the ability of atropine to relax pulmonary artery rings may be dependent upon the mechanism of action of the precontracting agonist and also, the vasorelaxant effect of atropine is not wholly mediated by the release of NO (nitric oxide)/EDRF.

In the present study, the effect of 5-HT2A receptor blockers in CA1 region of rat hippocampus on spatial learning was assessed in a T-maze, a spatial discrimination task. Rats were canulated bilaterally and injected daily vehicle (saline), 5-HT2A-selective antagonist, ketanserin (0.6, 1.2 or 2.4 µg/0.5 µl) and pirenperone (0.1, 0.3, 1.2 or 2.4 µg/0.5 µl) into the cannula 30 minutes before training. Results indicated that ketanserin and pirenperon did not affect spontaneous alternation and also did not induce a significant effect on trials to reach criterion and errors made by animals throughout spatial discrimination and reversal learning. But, in the rats that recieved ketanserin produced dose dependent decrease in the latencies to enter the chosen arm in both learning and reversal stages. During extinction, no change was observed in the choice of the previously reinforced arm in both ketanserin and pirenperone groups. The slope of latency in the ketanserin group that had received the highest dose of ketanserin (2.4 µg) than the sham operated group but not in the pirenperone group. These findings suggest that 5-HT2A receptors blockade (ketanserin, but not pirenperone) in the CA1 region may decrease decision time and increase behavioural flexibility in T-maze.

Indium is a heavy metal belonging to group IIIa. It is used as a radioimaging and chemotherapeutic agent in diagnosis and also in the treatment of cancers. It is believed that indium may interfere with iron metabolism and reduce cell growth in cancer tissue. The present report was established to study the binding of iron and indium to apo-transferrin (apo-tf) and to identify amino acids involved in this process. The pure human transferrin was used and iron and indium, as citrate complexes (1:20), were added to apo-tf. The binding constant was calculated using spectrofluorometric titration technique. Maximum wavelengths for excitation and emission of apo-tf were 300 and 335 nm, respectively. When apo-tf was complexed with iron, the emission was decreased 69% whereas, the binding of indium to apo-tf increased the emission 29%. The approximate binding constant for iron-transferrin complexes were 1×108 M-1 and 0.11 ×108 M-1, respectively. The pKa's of aspartate, histidine, tyrosine, lysine and arginin were identified. The data indicated that the indium competes with iron in binding to apo-tf. Although, the binding sites for these two ions seems to be similar, the binding of iron to apo-tf is approximately 9 times more tightly than indium.