Guinea Pig as an appropriate model for colonization of helicobacter pylori

Animal models have been proven useful in elucidating the details of interaction between pathogenic bacteria and their human hosts, in addition to assessing the efficacy of therapeutic compounds and vaccines. In this study, we investigate the colonization of Helicobacter pylori [H. pylori] in experimentally-infected guinea pigs over a six-month period. A bacterial suspension was prepared by mixing four H. pylori isolates obtained from patients diagnosed with gastric ulcer. Within a one week period, five female guinea pigs were dosed orally with bacterial suspension for a total of three times. One control animal was gavaged with normal saline. Stool samples were collected at two-week intervals for six months. We used PCR, the stool antigen test, and indirect immunofluorescence assay [IFA] to assess samples for the presence of H, pylori. Stomachs obtained from two chloroform-killed animals, at 8 and 24 weeks, were investigated for histopathologic changes. H. pylori 16S rDNA was amplified from the stool samples of five guinea pigs. The stool antigen test was also positive in all five animals. IFA demonstrated the presence of H, pylori antigens in the stools from all five animals. PCR, stool antigen test and IFA results showed no H. pylori in the stool of the control animal. We observed infiltration of mature lymphocytes and plasma cells in the stomachs of animals killed at 8 and 24 weeks. The occurrence of H, pylori 16S rDNA and antigens in stool samples of guinea pigs demonstrated persistent colonization off H, pylori in the stomachs of guinea pigs. Histopathological findings have confirmed mild-severe gastritis induced by the bacterial infection. The stomach of a guinea pig is similar to the human stomach, in that it is sterile, lined by glandular epithelium, lacks a vitamin C synthesizing system and produces the cytokine interleukin-8. Accordingly, the guinea pig can be considered an appropriate animal model for long-term experiments to follow the process of H, pylori pathogenesis or to assess the efficacy of antibiotics or vaccines

Comparison of the effect of non-antifungal and antifungal agents on Candida isolates from the gastrointestinal tract

Non-antifungal drugs appear promising in treatment of opportunistic infections of Candida spp. that are often resistant to current antifungals. The broth macrodilution method [NCCLS M27-P document] was used to compare the antifungal activity of trifluoperazine, pro-pranolol, and lansoprazole with that of ketoconazole and amphotericin B, using 50 yeast isolates from the Gl tract. The minimum fungicidal concentrations [MFCs], resistance rates and the time required for fungicidal activity of the drugs [2 - 48 hours] were determined. The most effective antifungal activity was exhibited by trifluoperazine. Its MFC was 32 microg/mL for Candida albicans [3.3% resistance] and Candida spp. [0% resistance] yeasts, and 64 ug/mL for Candida tropicalis with 10% resistance. The MFC for C. albicans and Candida spp. was comparable to that of ketoconazole. However, the time required for the inhibitory effect [6 hr] was shorter than that of ketoconazole [48 hr] or amphotericin B [24 hr]. The time required for the inhibitory activity on C. tropicalis was 24 hr, which was shorter than that of ketoconazole and amphotericin B [48 hr]. A considerable number [40%] of Candida spp. showed resistance to ketoconazole, and 20% of C. tropicalis showed resistance to amphotericin B. Trifluoperazine, an antipsychotic drug, exhibited effective antifungal activity with the MFC, comparable to ketoconazole [32 microg/mL]. Among the three yeast groups, C. tropicalis showed resistance to trifluoperazine and amphotericin B, and Candida spp. was considerably resistant to ketoconazole. Trifluoperazine could be considered as an alternative antifungal when encountering Candida spp. resistant to current antifungals

Precancerous conditions after H. pylori eradication: a randomized double blind study in first degree relatives of gastric cancer patients

Regression of precancerous lesions after H. pylori eradication remains controversial. This study evaluates the change and topography in first degree relatives [FOR] of gastric cancer [GC] patients following H. pylori eradication. Participants underwent endoscopy with antrum and corpus histological examinations. Subjects with pangastritis were randomly allocated to placebo or eradication therapy and followed over 41/2 years. Among 989 evaluated FDR, we excluded 468 patients as follows: 108 had macroscopic lesions, 243 had no evidence of any H. pylori infection, and 117 were excluded for other reasons. The remaining subjects [n = 521] were allocated to therapy [group A, n = 261] or placebo [group B, n = 260] groups. Interim analysis of 403 subjects [201 placebo, 202 therapy] showed regression of atrophy [60 out of 97 in the antrum and 37 out of 104 in the corpus] in H. pylori-eradicated versus regression of atrophy [57 out of 184 in the antrum and 23 out of 173 in the corpus] in non-H. pylori-eradicated cases over 21/2 years [P < 0.0001]. No regression of intestinal metaplasia [IM] occurred in the antrum and corpus of treated subjects over 41/2 years. However, progression of IM occurred in the antrum in 17 out of 90 patients in the non-H. pylori-eradicated versus 4 out of 68 H. pylori-eradicated subjects after 41/2 years [P < 0.05]. Eradication of H. pylori is associated with regression of gastric atrophy but not IM, even in its early stages. Gastric atrophy and IM in the antrum have shown more rapid progression in cases not treated for H. pylori infection [over 41/2 years follow-up] compared to H. pylori-eradicated cases

19-year survival in a patient with rectosigmoid liver metastasis

We present the case of an 82-year-old man diagnosed with rectosigmoid cancer and liver metastasis who survived for 19 years following treatment. At the age of 64, the patient twice experienced mucus excretion for which he underwent a colonoscopy that resulted in a diagnosis of rectosigmoid cancer the patient underwent surgery for resection of the tumor and liver metastasis. Histopathology was notable for a diagnosis of rectal adenocarcinoma that infiltrated the entire thickness of the wall, with metastasis to the liver and no lymph node involvement. Post-operative chemotherapy was administered for about four months. The patient remained asymptomatic for 19 years which at that time he presented with liver metastasis, ascites and renal failure

Critical assessment of progress of medical sciences in Iran and Turkey: the way developing countries with limited resources should make effective contributions to the production of science

Scientific progress is an important indicator for the social and economic developments of any country. According to various reports, worldwide, Iran has the most growth in the field of science due to a high increase in the numbers of publications during the past decade. The aim of this study is to assess not only the quantity, but also the quality of publications of indexed Iranian journals and compare them to Turkey, as an Islamic neighboring country, in addition to the contributions of these two countries to our Knowledge. A number of international journals with high impact factors were selected to assess the contributions of scientists from Iran and Turkey to the medical sciences. English medical journals from Iran and Turkey indexed by the ISI Web of Sciences with known impact factors [IF] announced at the beginning of 2010 were included for evaluation. We calculated the number of all articles published from the beginning of 2007 until the October 2010, the number of total citations, and citations from authors outside both countries for each journal. In addition, we selected all articles cited at least six times by authors outside of both countries and discussed their content with regard to originality and novelty, as well as their contributions to current knowledge. Furthermore, 60 international journals in basic or clinical research with IF greater than 6 were selected for the magnitude of contributions of both countries to our scientific Knowledge. In 2010, out of a total of 21 Iranian journals indexed in ISI since 2007, only 12 have a known IF with a mean of 0.39 [range: 0.07 - 0.97], whereas out of 28 Turkish medical journals indexed in ISI, 15 have a known IF [mean: 0.35, range: 0.05 - 0.82]. The total number of articles published since 2007 from Iran, total citations and total citations by authors from outside Iran were 2080, 1218, and 463, respectively. The same data related to Turkish journals were 4876, 2036, and 1331, respectively. Indeed, the mean citations per article by foreign authors for Iranian and Turkish researchers were 0.19 and 0.3, respectively. Of the total articles during this period, only seven from Iran and nine from Turkey have been cited at least six times by authors outside the two countries. Iran had 23 and Turkey 37 original publications in highly reputable international journals. Turkey was more represented in basic research and clinical observational studies than Iran. Despite high numbers of published articles, both countries have medical journals with very low comparable citation rates and IF. Only one out of three Turkish articles is cited once by authors outside of Turkey and one of five Iranian articles is cited by authors outside Iran. The few high-cited articles address new therapies and interventional studies or diseases commonly encountered regionally, and are the results of the efforts of a few individuals in highly specialized fields. Turkish scientists are inclined to publish their scientific works more than Iranians in distinguished international journals. These articles deal more with regional diseases that are not common in Western countries. Developing countries can only contribute to world science when they focus their efforts on teamwork in order to research ways to solve country-specific diseases and their own health problems

Increase in resistance rates of H. pylori isolates to metronidazole and tetracycline-comparison of three 3-year studies

Antimicrobials have been useful in the treatment of H.pylori-related dyspeptic diseases. However, emergence of resistant strains often decreases the eradication rates of H.pylori infections. Large-scale use of antimicrobials will lead to the diminishment of susceptible strains while allowing resistant survivors to outgrow and spread resistance genes. The aim of this study was to assess the change in antimicrobial resistance rate of H.pylori isolates from 2005 to 2008 and indicate the consequences of indiscriminate and widespread use of antimicrobials against H. pylori-and non-H.pylori-related infections. A total of 110 H. pylori strains were isolated from dyspeptic patients during 2005 to 2008 and tested for their susceptibility to antimicrobials using the disk diffusion method. MICs were determined for metronidazole [8 micro g/mL], tetracycline [0.5 micro g/mL], clarithromycin [2 micro g/mL], amoxicillin [1 micro g/mL] and furazolidone [0.5 micro g/mL]. Since the rates of resistance to metronidazole and tetracycline were remarkably high, another 50 isolates were tested for their susceptibility to metronidazole at the same MIC [8 micro g/mL] and tetracycline at MICs of 0.5, 1 and 2 micro g/mL. Resistance rates were compared to those obtained in our two previous studies between 1997-2000 and 2001-2004. The resistance rates of 110 H.pylori isolates to clarithromycin, amoxicillin and furazolidone were 7.3%, 7.3%, and 4.5%, respectively. Among 160 H.pylori isolates, 55.6% exhibited resistance to metronidazole and 38.1% to tetracycline. Compared to our two previous studies, the resistance rates of H.pylori isolates to current antimicrobials has changed over time. The change in resistance rates of clarithromycin, amoxicillin and furazolidone was not statistically significant. However, resistance to metronidazole and tetracycline showed a considerable increase from 33-36.3% to 55.6% and 0-0.7% to 38.1%, respectively. Emergence of resistance due to the intensive use of antibiotics has become a global public health problem. It appears that plasmid-carried genes are involved in the spread of resistance traits among bacteria. Results obtained in this study indicate that the increase in resistance rates of H.pylori isolates to metronidazole and tetracycline could be the indication of indiscriminate and frequent use of antibiotics in Iran

Antibacterial activity of twenty Iranian plant extracts against clinical isolates of helicobacter pylori

Due to increasing emergence of drug-resistance in Helicobacter pylori isolates, traditional plants are potentially valuable sources of novel anti-H. pylori agents. In this research, anti-H. pylori activity of the organic extracts of twenty native Iranian plants was determined against ten clinical isolates of H. pylori. Disc diffusion was used to determine the biological activity of 20 plant extracts as well as 8 antibiotics commonly used to treat H. pylori infections. Minimum inhibitory concentrations were also measured by tube and agar dilution methods for the biologically active plant extracts. Of the twenty plant extracts analyzed, sixteen exhibited good anti-H. pylori activity, using disc diffusion. The ten most active extracts were Carum bulbocastanum, Carum carvi, Mentha longifolia, Saliva limbata, Saliva sclarea, Ziziphora clinopodioides, Thymus caramanicus, Glycyrrhiza glabra, Xanthium brasilicum and Trachyspermum copticum. Minimum inhibitory concentrations measured for the 10 biologically active plant extracts were within the range of 31.25 to 500 micro g/ml. Among the ten plant extracts effective against H. pylori clinical isolates, Carum carvi, Xanthium brasilicum and Trachyspermum copticum showed the highest activity

Smoking and Gut

Smoking has not only enormous deleterious effects on cardiovascular, cerebral, and bronchial organs but also profoundly alters the function of all parts of the gastrointestinal tract through various mechanisms. Except the sole curiously observed benefit of smoking on the course of ulcerative colitis, it increases the prevalence of the common gastrointestinal diseases namely gastroesophageal acid reflux, peptic ulcer, and Crohn's diseases. It also increases the incidence of cancer of oral cavity, esophagus, stomach, pancreas, and liver mostly in a dose-response relationship and worsens the prognosis of colon cancer. The cessation of smoking is associated with the reduced incidence of cancer in the reported organs, but its effect on the regression of benign disease is not generally studied. The physicians must be aware not only of the harmful effect of smoking on the cardiovascular and bronchial systems, but also about the detrimental consequences of life-long smoking on the gastrointestinal tract and the increase of its benign and malignant diseases

Detection of Helicobacter pylori infection by imported IgG ELISA kits in comparison with Iranian home made kit

Helicobacter pylori [Hp] is a gram negative, spiral shaped bacterium which colonizes the gastric mucosa and induces gastroduodenal complications varying from mild gastritis with no clinical complications to peptic ulcer diseases and even gastric malignancies. The rate of Hp infection is 30-50% in developed countries whereas it has been rated up to 80% of the adult population in developing countries like Iran. Hp infection can be detected by various diagnostic methods. Culturing biopsy specimens and Rapid Urease Test [RUT] are the most common and reliable tests which can manifest Hp infection through proper sampling but these methods are invasive ones due to the need for endoscopy procedure in isolation of biopsy specimen. Application of serological assays are being increasingly used for epidemiological studies and detecting systemic immune responses toward past Hp infection. ELISA assays are the most popular techniques particularly in cases with no previous treatment. In this study we tested three imported IgG ELISA kits which are available for clinical diagnostics in detecting host sero-reactivity to Hp infection and compared them with a home made IgG ELISA kit. Histology and RUT were used as the gold standard tests for determination of Hp positive vs. Hp negative subjects using biopsy specimens from antrum. Sensitivity, specificity, accuracy and other required criteria were evaluated for each ELISA kit. According to the results the original criteria [Sensitivity and specificity] for each kit were as follows: BIOHIT [41.6%, 100%], Trinity [100%, 86.6%], Pishtaz [100%, 86.6%], Home made [100%, 92.6%]. Evaluation of these different IgG ELISA kits originating from different parts of the world and cross comparison of the results indicated that the cut off values should be refined for user country in order to obtain the highest sensitivity and specificity. These differences can be due to the vast geographic heterogeneity among Hp antigens. Furthermore, this study showed that home made ELISA kit can be substituted for imported ELISA kits due to its valid serological criteria