Alcoholdehydrogenase as an activating enzyme for N-nitrosodiethanolamine (NDELA): In vitro activation of NDELA to a potent mutagen in Salmonella typhimurium

Summary N-Nitrosodiethanolamine (NDELA), a potent carcinogen, has not so far been found to be mutagenic in a wide range of test systems. In particular, mutagenicity testing in Salmonella typhimurium with rat liver S-9 mix or microsomal fraction used for activation has failed to indicate mutagenicity. However, when incubated with alcohol dehydrogenase (ADH) in the presence of NAD, NDELA is converted to a potent mutagen. A possible mechanism of activation comprises the generation of an aldehyde as a primary metabolite formed by NAD/ADH and its subsequent rearrangement into cyclic intermediates. The latter might either be further metabolized or spontaneously decompose into various alkylating agents and glycolaldehyde. Standard test conditions used for the Ames test will not favor the detection of mutagens to be activated by NAD/ADH because they require the presence of NADPH, whereas ADH needs NAD to become an activating enzyme, as shown for NDELA.Dedicated to Professor Hermann Druckrey on the occasion of his 80th birthday     

Preventive Effects of the Probiotic Escherichia coli Strain Nissle 1917 on Acute Secretory Diarrhea in a Pig Model of Intestinal Infection

Pretreatment with the probiotic Escherichia colistrain Nissle 1917 (EcN) was assessed in a pig model of intestinal infection to prevent acute secretory diarrhea. In the model 10¹⁰ colony forming units of the porcine enterotoxigenic Escherichia coli Abbotstown (EcA) was given via orogastric tube to weaned piglets at day 21 postpartum (−EcN/+EcA group, n = 7). Forty-eight hours after challenge electrophysiological parameters of isolated intact jejunal epithelia were characterized in Ussing chambers. In agreement with clinical signs of diarrhea, tissues of challenged animals showed an overshoot of secretory response after stimulation of the cAMP-mediated second messenger pathway by forskolin, indicating higher excitability of chloride secretory systems under infected conditions. The data were compared with respective measurements from animals that got a daily dose of 10¹⁰ cfu of the probiotic EcN over 10 days before EcA challenge (+EcN/+EcA group; n = 4), from a group that received only EcN (+EcN/–EcA; n = 4), or from a group that remained totally untreated (−EcN/−EcA; n = 6). EcN pretreatment completely abolished clinical signs of secretory diarrhea in +EcN/+EcA animals. Furthermore, jejunum epithelia of these animals did not exhibit an overshoot of secretory response upon stimulation with forskolin. Our studies demonstrate for the first time the efficacy of prophylactic EcN in pig small intestine for preventing an effect of toxigenic EcA. This infection model with freshly weaned piglets may be predestinated to further characterize EcN effects on the cellular level, i.e., involved second messenger pathways, or it may also be useful to examine the efficacy of other substrates or microbe strains against secretory stimuli.     

Cancerous patients and outbreak of Escherichia coli: an important issue in oncology

The widespread of the Escherichia coli outbreak in Europe becomes an important public concern at global level. The infection can be serious and might result in death. The retrospective literature review on this specific topic is performed. In this specific brief article, the author presented and discussed on the problem of Escherichia coli infection in the cancerous patients. This is an actual important issue in medical oncology for the scenario of Escherichia coli epidemic.     

Inhibition of the growth of Plasmodium falciparum and Plasmodium berghei in vitro by an extract of Cochlospermum angolense (Welw.)

An extract of Cochlospermum angolense (Welw.) is used in the traditional medicine of Angola for the therapy of icterus and for the prophylaxis of malaria. From the roots of this plant red crystalline substances have been isolated and tested for their effect on Plasmodium falciparum in vitro and on the DNA and protein synthesis of Plasmodium berghei. The multiplication of P. falciparum was decreased to 50% of the control in the presence of 10 μg/ml extracted material and there was a total inhibition at a concentration of 50 μ/ml. If mice erythrocytes infected by P. berghei were incubated for 6 h with 25 μg/ml of the extract DNA synthesis was depressed to nearly background level. And, even more important, this effect could be demonstrated immediately. On the contrary, protein synthesis continued for at least 90 min at a reduced rate and stopped then. The results obtained show the direct antiparasitic effect of the substances extracted from C. angolense. The activity seems to be directed against DNA synthesis.     

Effect of ENPP1/PC-1-K121Q and PPARgamma-Pro12Ala polymorphisms on the genetic susceptibility to T2D in the Tunisian population

Diabetes mellitus is the most common chronic metabolic disease. The raising diabetes epidemic is unfolding as an interaction between several environmental factors and a genetic predisposition. The aim of the current study was to evaluate the role of the PPARγ-Pro12Ala and ENPP1-K121Q polymorphisms on type 2 diabetes (T2D) risk in a case–control study in the Tunisian population. To assess for any association of ENPP1-K121Q and PPARγ-Pro12Ala polymorphisms with T2D risk, we analysed the genotypic and allelic distributions of each variant in the studied cohort. Our results support that the genetic variation at ENPP1-K121Q predisposes to T2D in the Tunisian population after adjustment on gender, age and BMI status (OR = 1.55, 95%CI [1.11–2.16], p = 0.007).Conversely, the PPARγ-Pro12Ala variant seems not to have a significant effect on T2D risk in our Tunisian cohort. However, the minor A-allele would convey protection against overweight in the Tunisian population. In fact, the over weighted subjects showed a significantly lower frequency of A-allele than lean controls (OR = 0.49, 95%CI [0.25–0.97], p = 0.02). In conclusion, our findings support the hypothesis that ENPP1-121Q is involved in the genetic susceptibility of T2D in the Tunisian population, while the PPARγ-12Ala allele may confer protection against overweight.     

Differing roles of protein kinase C-zeta in disruption of tight junction barrier by enteropathogenic and enterohemorrhagic Escherichia coli

BACKGROUND & AIMS: Enteropathogenic Escherichia coli and enterohemorrhagic E. coli harbor highly homologous pathogenicity islands yet show key differences in their mechanisms of action. Both disrupt host intestinal epithelial tight junctions, but the effects of enteropathogenic E. coli are more profound than those of enterohemorrhagic E. coli. The basis for this is not understood. The atypical protein kinase C isoform, protein kinase C-zeta, associates with and regulates the tight junction complex. The aim of this study was to compare the role of protein kinase C-zeta in the disruption of tight junctions after infection with enteropathogenic E. coli and enterohemorrhagic E. coli. METHODS: Model intestinal epithelial monolayers infected by enteropathogenic E. coli or enterohemorrhagic E. coli were used for these studies. RESULTS: Neither bisindolylmaleimide nor G?6976, which block several protein kinase C isoforms but not protein kinase C-zeta, protected against the decrease in transepithelial electrical resistance after enteropathogenic E. coli infection. Rottlerin at concentrations that block novel and atypical isoforms, including protein kinase C-zeta, significantly attenuated the decrease in transepithelial electrical resistance. The specific inhibitory peptide, myristoylated protein kinase C-zeta pseudosubstrate, also significantly decreased the enteropathogenic E. coli -associated decrease in transepithelial electrical resistance and redistribution of tight junction proteins. In contrast to enteropathogenic E. coli, the level of protein kinase C-zeta enzyme activity stimulated by enterohemorrhagic E. coli was transient and minor, and protein kinase C-zeta inhibition had no effect on the decrease in transepithelial electrical resistance or the redistribution of occludin. CONCLUSIONS: The differential regulation of protein kinase C-zeta by enteropathogenic E. coli and enterohemorrhagic E. coli may in part explain the less profound effect of the latter on the barrier function of tight junctions.     

Ambient salinity modifies the action of triiodothyronine in the air-breathing fish Anabas testudineus Bloch: Effects on mitochondria-rich cell distribution, osmotic and metabolic regulations

The hydromineral and metabolic actions of thyroid hormone on osmotic acclimation in fish is less understood. We, therefore, studied the short-term action of triiodothyronine (T₃), the potent thyroid hormone, on the distribution and the function of gill mitochondria-rich (MR) cells and on the whole body hydromineral and metabolic regulations of air-breathing fish (Anabas testudineus) adapted to either freshwater (FW) or acclimated to seawater (SA; 30 g L⁻¹). As expected, 24 h T₃ injection (100 ng g⁻¹) elevated (P < 0.05) plasma T₃ but classically reduced (P < 0.05) plasma T₄. The higher Na⁺, K⁺-ATPase immunoreactivity and the varied distribution pattern of MR cells in the gills of T₃-treated FW and SA fish, suggest an action of T₃ on gill MR cell migration, though the density of these cells remained unchanged after T₃ treatment. The ouabain-sensitive Na⁺, K⁺-ATPase activity, a measure of hydromineral competence, showed increases (P < 0.05) in the gills of both FW and SA fish after T₃ administration, but inhibited (P < 0.05) in the kidney of the FW fish and not in the SA fish. Exogenous T₃ reduced glucose (P < 0.05) and urea (P < 0.05) in the plasma of FW fish, whereas these metabolites were elevated (P < 0.05) in the SA fish, suggesting a modulatory effect of ambient salinity on the T₃-driven metabolic actions. Our data identify gill MR cell as a target for T₃ action as it promotes the spatial distribution and the osmotic function of these cells in both fresh water and in seawater. The results besides confirming the metabolic and osmotic actions of T₃ in fish support the hypothesis that the differential actions of T₃ may be due to the direct influence of ambient salinity, a major environmental determinant that alters the osmotic and metabolic strategies of fish.     

Investigations on the in vitro metacyclogenesis of a visceral and a cutaneous human strain of Leishmania infantum

The in vitro metacyclogenesis of a visceral (VL) and cutaneous (CL) human strain of Leishmania infantum was monitored in order to find out the kinetics of this process and the in vitro infective capacity for macrophages of the metacyclic promastigotes developed. To identify, enumerate, and separate the metacyclic population, the complement-dependent lysis by normal serum and the agglutination by peanut agglutinin (PNA) were used, as they were shown to be useful for the purpose of this study. Maximum percentage of metacyclics was detected by both techniques on the 4th day of growth for VL and the 6th day for CL, and was higher for the VL strain. The in vitro infectivity for macrophages of two strains was assayed, and the high parasitization data obtained were transformed in order to determine the increase of the parasite burden for macrophages throughout the incubation time of the experiments (2–72 h post-infection (p.i.)). This parameter is denominated the infectivity ratio (%I) and calculated as follows: (number of intracellular parasites per infected macrophage at `x' time p.i./number of intracellular parasites per infected macrophage at 2 h p.i.)×100. When %I was calculated for promastigotes unagglutinated by PNA (PNA−)—metacyclic or infective promastigotes—at any time of culture, the %I at 72 h p.i. was always much higher than for agglutinated promastigotes (2.1–12.5 times)—non-infective promastigotes—and unfractionated promastigotes from culture (1.7–9.5 times), especially with VL parasites. Likewise, the %I for VL PNA− promastigotes from the 4th day of culture was 1.9 times higher than for CL PNA− promastigotes from the 6th day of culture. The higher resistance to lysis by serum, percentage of metacyclics (PNA−), and infectivity ratio of VL than CL could be related to a higher spreading capability into the host body associated with higher pathogenic effects of the visceral strain than the cutaneous one.     

Assessing the effect of interaction between an FTO variant (rs9939609) and physical activity on obesity in 15,925 Swedish and 2,511 Finnish adults

Aims/hypothesis  Recent reports have suggested that genotypes at the FTO locus interact with physical activity to modify levels of obesity-related traits. We tested this hypothesis in two non-diabetic population-based cohorts, the first from southern Sweden and the second from the Botnia region of western Finland. Methods  In total 2,511 Finnish and 15,925 Swedish non-diabetic middle-aged adults were genotyped for the FTO rs9939609 variant. Physical activity was assessed by questionnaires and standard clinical procedures were conducted, including measures of height and weight and glucose regulation. Tests of gene × physical activity interaction were performed using linear interaction effects to determine whether the effect of this variant on BMI is modified by physical activity. Results  The minor A allele at rs9939609 was associated with higher BMI in both cohorts, with the per allele difference in BMI being about 0.13 and 0.43 kg/m² in the Swedish and Finnish cohorts, respectively (p < 0.0001). The test of interaction between physical activity and the rs9939609 variant on BMI was not statistically significant after controlling for age and sex in either cohort (Sweden: p = 0.71, Finland: p = 0.18). Conclusions/interpretation  The present report does not support the notion that physical activity modifies the effects of the FTO rs9939609 variant on obesity risk in the non-diabetic Swedish or Finnish adults studied here. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.