Helicobacter pylori vacuolating cytotoxin inhibits activation-induced proliferation of human T and B lymphocyte subsets

Helicobacter pylori are Gram-negative bacteria that persistently colonize the human gastric mucosa despite the recruitment of immune cells. The H. pylori vacuolating cytotoxin (VacA) recently has been shown to inhibit stimulation-induced proliferation of primary human CD4(+) T cells. In this study, we investigated effects of VacA on the proliferation of various other types of primary human immune cells. Intoxication of PBMC with VacA inhibited the stimulation-induced proliferation of CD4(+) T cells, CD8(+) T cells, and B cells. VacA also inhibited the proliferation of purified primary human CD4(+) T cells that were stimulated by dendritic cells. VacA inhibited both T cell-induced and PMA/anti-IgM-induced proliferation of purified B cells. Intoxication with VacA did not alter the magnitude of calcium flux that occurred upon stimulation of CD4(+) T cells or B cells, indicating that VacA does not alter early signaling events required for activation and proliferation. VacA reduced the mitochondrial membrane potential of CD4(+) T cells, but did not reduce the mitochondrial membrane potential of B cells. We propose that the immunomodulatory actions of VacA on T and B lymphocytes, the major effectors of the adaptive immune response, may contribute to the ability of H. pylori to establish a persistent infection in the human gastric mucosa.     

The relationship of Helicobacter pylori positivity with age, sex, and ABO/Rhesus blood groups in patients with gastrointestinal complaints in Turkey

BACKGROUND: To determine the magnitude of Helicobacter pylori infection in patients with gastrointestinal complaints in Turkey. METHODS: We studied 1680 patients with variable gastrointestinal complaints. The H. pylori infection status was determined using C-14 urea breath test (UBT). Overall, 1567 patients (548 male, 1019 female; age range 4-80 years, mean 29.37 +/- 17.30 years) were included in this study. The relationship between H. pylori positivity and age, sex, sociodemographic characteristic, blood groups, and gastrointestinal diagnosis was determined. RESULTS: H. pylori positivity was found to be 68%. The difference in positivity rates between age groups 4-9 years and other groups was statistically significant (p = .001). H. pylori positivity was 67.7% in males and 68.2% in females (p = .865). H. pylori positivity was 72.1, 65.1, 70, and 68.4% in blood groups A, B, AB, and O (p = .703), and 68.9% and 76.3% in Rh (+) and Rh (-) blood subgroups, respectively (p = .292). There was no statistically significant difference between H. pylori positivity and gastrointestinal diagnosis (p = .980). There was significant association between increased number of household members and low socioeconomic status, and H. pylori positivity (p < .001). Living in rural and suburban area was significantly associated with H. pylori positivity compared with living in urban. CONCLUSIONS: H. pylori infection positivity rate was 68% in symptomatic subjects in Turkey and the positivity rate was significantly lower at age 4-9 years than the other age groups. It was not related to gender, ABO, and Rh blood groups and gastrointestinal diagnosis. Low socioeconomic conditions and living in rural and suburban area were significantly associated with H. pylori positivity.     

DNA adducts in human placenta exposed to ambient environment and passive cigarette smoke during pregnancy

BACKGROUND: The risk of human diseases and abnormal development under the relatively reduced toxic environmental exposure conditions of passive cigarette smoke and urban pollution is emerging as significant. To assess the genotoxic potential of such exposure, we analyzed the DNA adducts of polynuclear aromatic hydrocarbons (PAH), a proven marker of genotoxicity, in human placental DNA samples of pregnancies monitored for passive cigarette smoke exposure. METHODS: Maternal exposure to active and passive cigarette smoke was evaluated by verbal disclosure and urinary nicotine and cotinine measurements. PAH-DNA adducts were assayed by ELISA using a polyclonal antibody against benzo[alpha]pyrene-diol-epoxide-DNA in placental DNA. Birth weights of infants were recorded in these monitored pregnancies. RESULTS: Urinary nicotine and cotinine values were reduced in the passive smoke-exposed group compared to smokers and similar to those in the nonsmoker ambient exposure group. PAH-DNA and nicotine/cotinine values were not correlated with birth weight of the infant. PAH-DNA adducts were present in approximately 25% of samples exposed to passive cigarette smoke and ambient environment. CONCLUSIONS: The study has revealed that a subpopulation of humans is predisposed to accumulating PAH adducts independent of high levels of PAH sources (e.g., maternal cigarette smoke exposure). Because DNA adducts promote genomic changes, it is likely that this subpopulation is susceptible to diverse changes in the genome that may influence human development.     

Histidine phosphorylation of the potassium channel KCa3.1 by nucleoside diphosphate kinase B is required for activation of KCa3.1 and CD4 T cells

The Ca2+ -activated K+ channel KCa3.1 is required for Ca2+ influx and the subsequent activation of B and T cells. Inhibitors of KCa3.1 are in development to treat autoimmune diseases and transplant rejection, underscoring the importance in understanding how these channels are regulated. We show that nucleoside diphosphate kinase B (NDPK-B), a mammalian histidine kinase, functions downstream of PI(3)P to activate KCa3.1. NDPK-B directly binds and activates KCa3.1 by phosphorylating histidine 358 in the carboxyl terminus of KCa3.1. Endogenous NDPK-B is also critical for KCa3.1 channel activity and the subsequent activation of CD4 T cells. These findings provide one of the best examples whereby histidine phosphorylation regulates a biological process in mammals, and provide an example whereby a channel is regulated by histidine phosphorylation. The critical role for NDPK-B in the reactivation of CD4 T cells indicates that understanding NDPK-B regulation should uncover novel pathways required for T cell activation.     

Lipid peroxidation and antioxidant status in blood and tissue of malignant breast tumor and benign breast disease

Changes in the levels of malondialdehyde (MDA), nitrate and nitrite (as an index of nitric oxide production), lipid hydroperoxide (LOH), total antioxidant capacity (TAC), lipids (total cholesterol and triglycerides) and lipoproteins (HDL- and LDL-cholesterol) were estimated in breast cancer patients (n = 15) and benign breast disease (n = 15). Serum and tissue MDA levels were found to be decreased in breast cancer patients compared to the benign group (p < 0.05). In contrast, nitrate and nitrite levels were increased in serum and tissue of the cancer group compared to benign breast disease patients (p < 0.05). Compared to the benign group, tissue TAC levels were elevated in the breast cancer patient group (p < 0.05). Total cholesterol and HDL-cholesterol were elevated in the benign group compared with cancer patients (p < 0.05). These findings support the hypothesis that lipid peroxidation in serum and tissue of benign breast disease is greater than in breast cancer. However, the enhanced levels of nitric oxide may be in response to inflammation in patients with breast cancer. Total antioxidant status is lower in benign tissue than in cancerous tissue, probably to compensate for this elevated free radical production.     

Impaired reproductive behavior by lack of GluR-B containing AMPA receptors but not of NMDA receptors in hypothalamic and septal neurons

The roles of ionotropic glutamate receptors in mammalian reproduction are unknown. We therefore generated mice lacking a major subtype of (S)-alpha-amino-3-hydroxy-5-methyl-isoxazolepropionic acid (AMPA) receptors or all N-methyl-d-aspartate (NMDA) receptors in GnRH neurons and other mainly limbic system neurons, primarily in hypothalamic and septal areas. Male mice without NMDA receptors in these neurons were not impaired in breeding and exhibited similar GnRH secretion as control littermates. However, male mice lacking GluR-B containing AMPA receptors in these neurons were poor breeders and severely impaired in reproductive behaviors such as aggression and mounting. Testis and sperm morphology, testis weight, and serum testosterone levels, as well as GnRH secretion, were unchanged. Contact with female cage bedding failed to elicit male sexual behavior in these mice, unlike in control male littermates. Their female counterparts had unchanged ovarian morphology, had bred successfully, and had normal litter sizes but exhibited pronounced impairments in maternal behaviors such as pup retrieval and maternal aggression. Our results suggest that NMDA receptors and GluR-B containing AMPA receptors are not essential for fertility, but that GluR-B containing AMPA receptors are essential for male and female reproduction-related behaviors, perhaps by mediating responses to pheromones or odorants.     

High level of endostatin in epididymal epithelium: protection against primary malignancies in this organ?

Rete testis and epididymis are rare locations for primary tumors or metastasis. Assuming that this may be related to expression level of angiogenic inhibitors, we focused our study on the expression pattern of collagen 18/endostatin. In situ hybridization and immunohistochemistry for collagen 18 and endostatin were carried out on sections of human rete testis and epididymis as well as on epididymal adenoma and human testicular tissue with or without carcinoma in situ (CIS). In situ hybridization revealed strong expression of collagen 18 mRNA in rete testis, efferent ducts and epididymal duct. Immunostaining showed collagen 18 in epithelium and basement membrane as well as in blood vessels of rete testis. Further, in both efferent ducts and epididymal duct, collagen 18 was mainly localized in the basement membrane of these ducts and of the blood vessel wall. Endostatin immunostaining was localized in the epithelium of rete testis, efferent ducts and epididymal duct. This pattern of endostatin staining was absent in epididymal adenoma tissue while tumor associated blood vessels exhibited strong endostatin staining. No endostatin staining was detectable in normal germinal epithelium and CIS cells while Leydig cells exhibited strong endostatin staining. High endostatin expression in epididymis may protect this organ against tumor development. Gene therapeutic strategies providing high expression of endostatin in normal epithelia may be useful to prevent tumor development.     

Magnesite Enrichment with Pseudomonas oryzihabitans Isolated from Magnesite Ore

Magnesite is a primary source of magnesium and its compounds. The major problem in its practical use are the impurities such as silicon, iron and calcium carbonate. Some magnesite ores in Turkey cannot be used due to a high amount of CaCO₃ (≥3%). In this study, bacterial isolates from magnesite quarries in Mersin were tested by plate assay for their ability to decalcify magnesite. A bacterial strain producing the largest clear zones in the plate assay was identified as Pseudomonas oryzihabitans by 16S rDNA-PCR and applied to magnesite ore. It was found to be effective in decalcifying magnesite ore without significant concurrent dissolution of the magnesium carbonate.