Modulation of anti-pathogenic activity in canine-derived Lactobacillus species by carbohydrate growth substrate

Aims: To investigate the effect of various carbon sources on the production of extracellular antagonistic compounds against two Escherichia coli strains and Salmonella enterica serotype Typhimurium by three canine-derived lactobacilli strains. Methods and Materials: Cell-free preparations, pH neutralized, were used in antibiotic disc experiments as an initial screening. The bacteria/carbohydrate combinations that showed inhibition of the growth of those pathogens, were further investigated in batch co-culture experiments. The cell-free supernatants of the cultures, that decreased the population number of the pathogens in the co-culture experiments to log CFU ml(-1) less than or equal to 4, were tested for inhibition of the pathogens in pure cultures at neutral and acidic pH. Conclusions: The results showed that the substrate seems to affect the production of antimicrobial compounds and this effect could not just be ascribed to the ability of the bacteria to grow in the various carbon sources. L. mucosae, L. acidophilus and L. reuteri, when grown in sugar mixtures consisting of alpha-glucosides (Degree of Polymerization (DP) 1-4) could produce antimicrobial compounds active against all three pathogens in vitro. This effect could not be attributed to a single ingredient of those sugar mixtures and was synergistic. This inhibition had a dose-response characteristic and was more active at acidic pH. Significance and Impact of the Study: Knowledge of the effect that the carbon source has on the production of antimicrobial compounds by gut-associated lactobacilli allows the rational design of prebiotic/probiotic combinations to combat gastrointestinal pathogens.

The intracellular genistein metabolite 5,7,3 ',4 '-tetrahydroxyisoflavone mediates G2-M cell cycle arrest in cancer cells via modulation of the p38 signaling pathway

The cellular actions of genistein are believed to mediate the decreased risk of breast cancer associated with high soy consumption. We have investigated the intracellular metabolism of genistein in T47D tumorigenic and MCF-10A nontumorigenic cells and assessed the cellular actions of resultant metabolites. Genistein selectively induced growth arrest and G2-M phase cell cycle block in T47D but not MCF10A breast epithelial cells. These antiproliferative effects were paralleled by significant differences in the association of genistein to cells and in particular its intracellular metabolism. Genistein was selectively taken up into T47D cells and was subject to metabolism by CYP450 enzymes leading to the formation of both 5,7,3',4'-tetrahydroxyisoflavone (THIF) and two glutathionyl conjugates of THIF THIF inhibited cdc2 activation via the phosphorylation of p38 MAP kinase, suggesting that this species may mediate genistein's cellular actions. THIF exposure activated p38 and caused subsequent inhibition of cyclin B1 (Ser 147) and cdc2 (Thr 161) phosphorylation, two events critical for the correct functioning of the cdc2-cyclin B1 complex. We suggest that the formation of THIF may mediate the cellular actions of genistein in tumorigenic breast epithelial cells via the activation of signaling through p38. (c) 2006 Elsevier Inc. All rights reserved.

Quercetin inhibits collagen-stimulated platelet activation through inhibition of multiple components of the glycoprotein VI signaling pathway

Background: The regulation of platelet function by pharmacological agents that modulate platelet signaling haspharmacolo proven a successful approach to the prevention of thrombosis. A variety of molecules present in the diet have been shown to inhibit platelet activation, including the antioxidant quercetin. Objectives: In this report we investigate the molecular mechanisms through which quercetin inhibits collagen-stimulated platelet aggregation. Methods: The effect of quercetin on platelet aggregation, intracellular calcium release, whole cell tyrosine phosphorylation and intracellular signaling events including tyrosine phosphorylation and kinase activity of proteins involved in the collagen-stimulated glycoprotein (GP) signaling pathway were investigated. Results: We report that quercetin inhibits collagen-stimulated whole cell protein tyrosine phosphorylation and intracellular mobilization of calcium, in a concentration-dependent manner. Quercetin was also found to inhibit various events in signaling generated by the collagen receptor GPVI. This includes collagen-stimulated tyrosine phosphorylation of the Fc receptor gamma-chain, Syk, LAT and phospholipase Cgamma2. Inhibition of phosphorylation of the Fc receptor gamma-chain suggests that quercetin inhibits early signaling events following stimulation of platelets with collagen. The activity of the kinases that phosphorylate the Fc receptor gamma-chain, Fyn and Lyn, as well as the tyrosine kinase Syk and phosphoinositide 3-kinase was also inhibited by quercetin in a concentration-dependent manner, both in whole cells and in isolation. Conclusions: The present results provide a molecular basis for the inhibition by quercetin of collagen-stimulated platelet activation, through inhibition of multiple components of the GPVI signaling pathway, and may begin to explain the proposed health benefits of high quercetin intake.

Hydroxytyrosol inhibits the proliferation of human colon adenocarcinoma cells through inhibition of ERK1/2 and cyclin D1

Extra virgin olive oil is rich in phenolic compounds which are believed to exert beneficial effects against many pathological processes, including the development of colon cancer. We show that one of the major polyphenolic constituents of extra virgin olive oil, hydroxytyrosol (HT), exerts strong anti-proliferative effects against human colon adenocarcinoma cells via its ability to induce a cell cycle block in G2/M. These antiproliferative effects were preceded by a strong inhibition of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation and a downstream reduction of cyclin D I expression, rather than by inhibition of p38 activity and cyclooxygenase-2 (COX-2) expression. These findings are of particular relevance due to the high colonic concentration of HT compared to the other olive oil polyphenols and may help explain the inverse link between colon cancer and olive oil consumption.

The development of the spatial extent of oculomotor inhibition

Inhibition is intimately involved in the ability to select a target for a goal-directed movement. The effect of distracters on the deviation of oculomotor trajectories and landing positions provides evidence of such inhibition. individual saccade trajectories and landing positions may deviate initially either towards, or away from, a competing distracter-the direction and extent of this deviation depends upon saccade latency and the target to distracter separation. However, the underlying commonality of the sources of oculomotor inhibition has not been investigated. Here we report the relationship between distracter-related deviation of saccade trajectory, landing position and saccade latency. Observers saccaded to a target which could be accompanied by a distracter shown at various distances from very close (10 angular degrees) to far away (120 angular degrees). A fixation-gap paradigm was used to manipulate latency independently of the influence of competing distracters. When distracters were close to the target, saccade trajectory and landing position deviated toward the distracter position, while at greater separations landing position was always accurate but trajectories deviated away from the distracters. Different spatial patterns of deviations across latency were found. This pattern of results is consistent with the metrics of the saccade reflecting coarse pooling of the ongoing activity at the distracter location: saccade trajectory reflects activity at saccade initiation while landing position reveals activity at saccade end. (C) 2009 Elsevier B.V. All rights reserved.

A systematic review of the routine monitoring of growth in children of primary school age to identify growth-related conditions

Objectives: To clarify the role of growth monitoring in primary school children, including obesity, and to examine issues that might impact on the effectiveness and cost-effectiveness of such programmes. Data sources: Electronic databases were searched up to July 2005. Experts in the field were also consulted. Review methods: Data extraction and quality assessment were performed on studies meeting the review's inclusion criteria. The performance of growth monitoring to detect disorders of stature and obesity was evaluated against National Screening Committee (NSC) criteria. Results: In the 31 studies that were included in the review, there were no controlled trials of the impact of growth monitoring and no studies of the diagnostic accuracy of different methods for growth monitoring. Analysis of the studies that presented a 'diagnostic yield' of growth monitoring suggested that one-off screening might identify between 1: 545 and 1: 1793 new cases of potentially treatable conditions. Economic modelling suggested that growth monitoring is associated with health improvements [ incremental cost per quality-adjusted life-year (QALY) of pound 9500] and indicated that monitoring was cost-effective 100% of the time over the given probability distributions for a willingness to pay threshold of pound 30,000 per QALY. Studies of obesity focused on the performance of body mass index against measures of body fat. A number of issues relating to human resources required for growth monitoring were identified, but data on attitudes to growth monitoring were extremely sparse. Preliminary findings from economic modelling suggested that primary prevention may be the most cost-effective approach to obesity management, but the model incorporated a great deal of uncertainty. Conclusions: This review has indicated the potential utility and cost-effectiveness of growth monitoring in terms of increased detection of stature-related disorders. It has also pointed strongly to the need for further research. Growth monitoring does not currently meet all NSC criteria. However, it is questionable whether some of these criteria can be meaningfully applied to growth monitoring given that short stature is not a disease in itself, but is used as a marker for a range of pathologies and as an indicator of general health status. Identification of effective interventions for the treatment of obesity is likely to be considered a prerequisite to any move from monitoring to a screening programme designed to identify individual overweight and obese children. Similarly, further long-term studies of the predictors of obesity-related co-morbidities in adulthood are warranted. A cluster randomised trial comparing growth monitoring strategies with no growth monitoring in the general population would most reliably determine the clinical effectiveness of growth monitoring. Studies of diagnostic accuracy, alongside evidence of effective treatment strategies, could provide an alternative approach. In this context, careful consideration would need to be given to target conditions and intervention thresholds. Diagnostic accuracy studies would require long-term follow-up of both short and normal children to determine sensitivity and specificity of growth monitoring.

Both tumour-promoting and non-promoting phorbol esters inhibit 125I-EGF binding and stimulate the phosphorylation of a 80kd protein kinase C substrate protein in intact Swiss 3T3 cells

Sapintoxin A (SAP A) and 12-deoxyphorbol 13-phenylacetate (DOPP), are two biologically active but non-turnour-promoting phorbol esters that potently bind to and activate the phorbol ester receptor, protein kinase C (PKC). SAP A and DOPP cause a dose-dependent increase in the phosphorylation of an 80 kd (80K) substrate protein for PKC in Swiss 3T3 cells. A similar dose—response effect was seen with sapintoxin D (SAP D), the stage 2 promoting analogue of 12-O-tetradecanoylphorbol-13-acetate and the complete promoter phorbol 12,13-dibutyrate (PDB). The doses resulting in a half maximal phosphorylation of this protein (Ka were 20 nM (SAP A), 45 nM (DOPP), 23 nM (SAP D) and 37 nM (PDB). Both non-promoting and phorbol esters induced a dose-dependent inhibition of [125I]epidermal growth factor (EGF) binding to its receptor in Swiss 3T3 cells. The doses required for 50% inhibition of binding (Ki) were: 8 nM (SAP A), 16 nM (DOPP), 14 nM (SAP D) and 17 nM (PDB). The results clearly demonstrate that induction of phosphorylation of the Pu 80K phosphoprotein and inhibition of [125I]EGF binding in Swiss 3T3 cells following exposure to phorbol esters is independent of the tumour-promoting activity of these compounds. The fact that SAP A, DOPP, SAP D and PDB are mitogenic for a variety of cell types and that exposure to these compounds leads to 80K phosphorylation and inhibition of [125I]EGF binding, suggests that these early biological events may play a role in the mitogenic response induced by these compounds.

A structural basis for the inhibition of collagen-stimulated platelet function by quercetin and structurally related flavonoids

Background and purpose: Molecular mechanisms underlying the links between dietary intake of flavonoids and reduced cardiovascular disease risk are only partially understood. Key events in the pathogenesis of cardiovascular disease, particularly thrombosis, are inhibited by these polyphenolic compounds via mechanisms such as inhibition of platelet activation and associated signal transduction, attenuation of generation of reactive oxygen species, enhancement of nitric oxide production and binding to thromboxane A2 receptors. In vivo, effects of flavonoids are mediated by their metabolites, but the effects and modes of action of these compounds are not well-characterized. A good understanding of flavonoid structure–activity relationships with regard to platelet function is also lacking. Experimental approach: Inhibitory potencies of structurally distinct flavonoids (quercetin, apigenin and catechin) and plasma metabolites (tamarixetin, quercetin-3′-sulphate and quercetin-3-glucuronide) for collagen-stimulated platelet aggregation and 5-hydroxytryptamine secretion were measured in human platelets. Tyrosine phosphorylation of total protein, Syk and PLCγ2 (immunoprecipitation and Western blot analyses), and Fyn kinase activity were also measured in platelets. Internalization of flavonoids and metabolites in a megakaryocytic cell line (MEG-01 cells) was studied by fluorescence confocal microscopy. Key results: The inhibitory mechanisms of these compounds included blocking Fyn kinase activity and the tyrosine phosphorylation of Syk and PLCγ2 following internalization. Principal functional groups attributed to potent inhibition were a planar, C-4 carbonyl substituted and C-3 hydroxylated C ring in addition to a B ring catechol moiety. Conclusions and implications: The structure–activity relationship for flavonoids on platelet function presented here may be exploited to design selective inhibitors of cell signalling.

Sea-breeze modification of the growth of a marine internal boundary layer

A numerical mesoscale model is used to make a high-resolution simulation of the marine boundary layer in the Persian Gulf, during conditions of offshore flow from Saudi Arabia. A marine internal boundary layer (MIBL) and a sea-breeze circulation (SBC) are found to co-exist. The sea breeze develops in the mid-afternoon, at which time its front is displaced several tens of kilometres offshore. Between the coast and the sea-breeze system, the MIBL that occurs is consistent with a picture described in the existing literature. However, the MIBL is perturbed by the SBC, the boundary layer deepening significantly seaward of the sea-breeze front. Our analysis suggests that this strong, localized deepening is not a direct consequence of frontal uplift, but rather that the immediate cause is the retardation of the prevailing, low-level offshore wind by the SBC. The simulated boundary-layer development can be accounted for by using a simple 1D Lagrangian model of growth driven by the surface heat flux. This model is obtained as a straightforward modification of an established MIBL analytic growth model.

Insulin, glucagon-like peptide 1, glucose-dependent insulinotropic polypeptide and insulin-like growth factor I as putative mediators of the hypolipidemic effect of oligofructose in rats

The addition of oligofructose as a dietary fiber decreases the serum concentration and the hepatic release of VLDL-triglycerides in rats. Because glucose, insulin, insulin-like growth factor I (IGF-I) and gut peptides [i.e., glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1)]) are factors involved in the metabolic response to nutrients, this paper analyzes their putative role in the hypolipidemic effect of oligofructose. Male Wistar rats were fed a nonpurified diet with or without 10% oligofructose for 30 d. Glucose, insulin, IGF-I and GIP concentrations were measured in the serum of rats after eating. GIP and GLP-1 contents were also assayed in small intestine and cecal extracts, respectively. A glucose tolerance test was performed in food-deprived rats. Serum insulin level was significantly lower in oligofructose-fed rats both after eating and in the glucose tolerance test, whereas glycemia was lower only in the postprandial state. IGF-I serum level did not differ between groups. GIP concentration was significantly higher in the serum of oligofructose-fed rats. The GLP-1 cecal pool was also significantly higher. In this study, we have shown that cecal proliferation induced by oligofructose leads to an increase in GLP-1 concentration. This latter incretin could be involved in the maintenance of glycemia despite a lower insulinemia in the glucose tolerance test in oligofructose-fed rats. We discuss also the role of hormonal changes in the antilipogenic effect of oligofructose.

Oxygen isotope composition of bivalve seasonal growth increments and ambient water in the rivers Rhine and Meuse

The application of oxygen isotope ratios ({delta}18O) from freshwater bivalves as a proxy for river discharge conditions in the Rhine and Meuse rivers is investigated. We compared a dataset of water temperature and water {delta}18O values with a selection of recent shell {delta}18O records for two species of the genus Unio in order to establish: (1) whether differences between the rivers in water {delta}18O values, reflecting river discharge conditions, are recorded in unionid shells; and (2) to what extent ecological parameters influence the accuracy of bivalve shell {delta}18O values as proxies of seasonal, water oxygen isotope conditions in these rivers. The results show that shells from the two rivers differ significantly in {delta}18O values, reflecting different source waters for these two rivers. The seasonal shell {delta}18O records show truncated sinusoidal patterns with narrow peaks and wide troughs, caused by temperature fractionation and winter growth cessation. Interannual growth rate reconstructions show an ontogenetic growth rate decrease. Growth lines in the shell often, but not always, coincide with winter growth cessations in the {delta}18O record, suggesting that growth cessations in the shell {delta}18O records are a better age estimator than counting internal growth lines. Seasonal predicted and measured {delta}18O values correspond well, supporting the hypothesis that these unionids precipitate their shells in oxygen isotopic equilibrium. This means that (sub-) fossil unionids can be used to reconstruct spring-summer river discharge conditions, such as Meuse low-discharge events caused by droughts and Rhine meltwater-influx events caused by melting of snow in the Alps.