Reduction in extracellular superoxide dismutase activity in African-American patients with hypertension

Superoxide anions react with nitric oxide to form peroxynitrite and hence reduce the bioavailability of nitric oxide in the arteries. Extracellular superoxide dismutase (EC-SOD) is a major superoxide scavenger in human plasma and vascular tissues. The objective of this study is to assess whether essential hypertension is associated with an alteration in EC-SOD activity. In this report, blood samples were obtained from hypertensive (n=39) and normotensive (n=37) African-Americans. Plasma EC-SOD activity was measured using in-gel activity staining and spectrophotometric assays, EC-SOD protein level was measured using Western blotting, nitrotyrosine was measured using slot blotting, 8-isoprostane was measured with an enzyme immunoassay, and plasma copper and zinc concentrations were measured using an atomic absorption assay. Our data demonstrate that the copper, zinc, and plasma EC-SOD protein concentrations in the hypertensive and normotensive subjects are indistinguishable. Compared to normotensive controls, hypertensive patients have significantly reduced plasma EC-SOD activity. Plasma nitrotyrosine and 8-isoprostane levels are significantly higher in the hypertensive patients than in normotensive controls. Results from this study suggest that a reduction in EC-SOD activity in hypertensive patients is not due to a down-regulation of the SOD3 gene (encoding EC-SOD) or deficiency in mineral cofactors. Furthermore, the reduced EC-SOD activity might be at least partially responsible for the increased oxidative stress, as reflected by increased plasma nitrotyrosine and 8-isoprostane, in hypertensive subjects.     

Efficient immunization and cross-priming by vaccine adjuvants containing TLR3 or TLR9 agonists complexed to cationic liposomes

Complexing TLR9 agonists such as plasmid DNA to cationic liposomes markedly potentiates their ability to activate innate immunity. We therefore reasoned that liposomes complexed with DNA or other TLR agonists could be used as effective vaccine adjuvants. To test this hypothesis, the vaccine adjuvant effects of liposomes complexed to TLR agonists were assessed in mice. We found that liposomes complexed to nucleic acids (liposome-Ag-nucleic acid complexes; LANAC) were particularly effective adjuvants for eliciting CD4(+) and CD8(+) T cell responses against peptide and protein Ags. Notably, LANAC containing TLR3 or TLR9 agonists effectively cross-primed CD8(+) T cell responses against even low doses of protein Ags, and this effect was independent of CD4(+) T cell help. Ag-specific CD8(+) T cells elicited by LANAC adjuvants were functionally active and persisted for long periods of time in tissues. In a therapeutic tumor vaccine model, immunization with the melanoma peptide trp2 and LANAC adjuvant controlled the growth of established B16 melanoma tumors. In a prophylactic vaccine model, immunization with the Mycobacterium tuberculosis protein ESAT-6 with LANAC adjuvant elicited significant protective immunity against aerosol challenge with virulent M. tuberculosis. These results suggest that certain TLR agonists can be combined with cationic liposomes to produce uniquely effective vaccine adjuvants capable of eliciting strong T cell responses against protein and peptide Ags.     

The role of TCR engagement and activation-induced cell death in sepsis-induced T cell apoptosis

Sepsis induces extensive apoptosis in T and B cells suggesting that the loss of immune effector cells could be one explanation for the profound immunosuppression observed in this disorder. Unfortunately, the mechanisms responsible for lymphocyte apoptosis in sepsis remain unknown. In T cells, apoptosis can occur through activation-induced cell death (AICD) in which engagement of the Ag receptors by cognate Ag or polyclonal activators such as bacteria-derived superantigens induces activation, proliferation, and apoptosis. We examined whether proliferation and AICD are necessary for apoptotic cell death in sepsis using normal and TCR transgenic mice. Results show that although sepsis resulted in activation of a small percentage of T cells, no proliferation was detected during the first 48 h following onset, a time when extensive apoptosis is observed. We also observed that T cells do not enter the cell cycle, and stimulation via the TCR in TCR transgenic animals does not enhance or decrease cell death in sepsis. Interestingly, T cells recovered from septic mice retained their ability to proliferate and synthesize cytokines albeit at reduced levels. With the exception of IL-10, which was increased in lymphocytes from mice with sepsis, sepsis caused a decrease in the production of both proinflammatory and anti-inflammatory cytokines. We conclude that lymphocyte apoptosis in sepsis does not require proliferation, TCR engagement, or AICD. Thus the immunosuppression observed in sepsis cannot be the result of T cell deletion via the TCR.     

The influence of genotype and environment on the fecundity and facultative expression of apomixis inHieracium pilosella

The potential for sexual reproduction in the facultative apomictHieracium pilosella was determined by pollinating with the closely related but morphologically distinctH. aurantiacum. The hybrid characteristics of the sexually produced progeny were used as markers for sex. Crossing was carried out under a range of environmental treatments to test the influence of (1) field versus glasshouse conditions, (2) nutrient level and the presence of a pathogen, and (3) photoperiod on the frequency of sex in facultative apomicticH. pilosella. We found significantly more sexual reproduction in the glasshouse than in the field for the two populations tested, but no influence of nutrient level, presence of the pathogen, or individual genotype. Photoperiod was not a significant factor for the single population tested. In several of the experiments seed production was significantly different between the treatments, despite the absence of an effect on the frequency of sex, indicating greater plasticity in this trait. In all three experiments a positive association was found between fecundity and the frequency of sex, with crosses producing sexual progeny having significantly more offspring than those that produced progeny exclusively via apomixis. We hypothesise that the cost of sex in this species may be offset by an increase in fecundity, with the cost of meiosis “diluted” by an increase in total progeny production.     

Changes in the erythrocyte glutathione concentration in the course of diabetes mellitus

This study aims to evaluate the significance of the changes of erythrocyte reduced glutathione (GSH) in the course of diabetes mellitus including the pre-diabetes stage and cardiovascular disease co-morbidity. A total of 222 participants (female:male, 107:115) were selected and their erythrocyte GSH levels were measured. The participants were divided into four groups: (i) control; (ii) those with blood glucose level > or =5.6 mmol/l but < 6.9 mmol/l as pre-diabetes mellitus with no other pathology; (iii) diabetes without co-morbidity; and (iv) those with diabetes mellitus and cardiovascular disease. Statistical analysis was by ANOVA followed by a Fisher's LSD post hoc test. We observed that GSH concentration was significantly different between groups (P < 0.04). The Fisher's post hoc test indicated significant differences in erythrocyte GSH levels between the pre-diabetes mellitus and diabetes mellitus groups compared to control (P < 0.005 and P < 0.05, respectively). A statistically significant change (P < 0.001) involving an initial fall followed by a rise in erythrocyte GSH levels was observed when diabetes mellitus and diabetes mellitus+cardiovascular disease groups were combined and assessed with respect to period of diabetes. We conclude that oxidative stress is already present in the pre-diabetes stage as determined by the fall in GSH, representing the initial phase of oxidative stress in diabetes mellitus progression. This finding provides evidence that antioxidant markers such as GSH could be a useful tool for pre-diabetes mellitus screening.     

Evaluation of live-culture-producing lacticin 3147 as a treatment for the control of Listeria monocytogenes on the surface of smear-ripened cheese

AIMS: A live Lactococcus lactis culture, producing the two-component broad spectrum bacteriocin lacticin 3147, was assessed for ability to inhibit the food pathogen Listeria monocytogenes on the surface of smear-ripened cheese. METHODS AND RESULTS: In initial experiments, the addition of Listeria to a lacticin 3147-containing fermentate produced with L. lactis DPC4275 (a transconjugant strain derived from L. lactis DPC3147) resulted in at least a 4 log reduction of the pathogen in 30 min. Two separate trials were performed in order to assess the most suitable method for application of the potential protective culture to smear-ripened cheese. In the initial trial, the L. lactis was sprayed onto the surface of the cheese either before or after Listeria was deliberately applied. Application of the culture following Listeria challenge, yielded up to a 1000-fold reduction of the pathogen in contrast to the pretreatment where Listeria numbers were unaffected. In a further trial, three applications of the live lacticin 3147-producing culture was used on a cheese surface containing Listeria. Listeria numbers were found to be up to 100-fold lower than in the cheese treated with L. lactis DPC4268 (control). CONCLUSION: While application of the live lacticin 3147 producer did not give complete elimination of the pathogen the results nonetheless demonstrate the potential of the bioprotectant for improving the safety of smear-ripened cheeses and particularly those that contain low level contamination with Listeria. SIGNIFICANCE AND IMPACT OF THE STUDY: The application of lacticin 3147 as a live-culture can serve as a bioprotectant for the control of L. monocytogenes on the surface of smear-ripened cheese.     

A lacticin 3147 enriched food ingredient reduces Streptococcus mutans isolated from the human oral cavity in saliva

AIMS: To isolate and characterise Streptococcus mutans from Irish saliva samples and to assess their sensitivity to a food-grade preparation of the lantibiotic, lacticin 3147, produced by Lactococcus lactis DPC3147. METHODS AND RESULTS: Saliva samples collected from children with varying oral health status were screened on Mitis Salivarius agar for the presence of pathogenic streptococci. Following selective plating, 16S rDNA sequencing and Pulsed Field Gel Electrophoresis (PFGE), 15 distinct strains of Strep. mutans were identified. These were grouped according to their relative sensitivity to lacticin 3147 which ranged from 0.78 to 6.25%; relative to a sensitive indicator strain, Lactococcus lactis ssp. lactis HP. Inhibition of indicator Strep. mutans strains from sensitive, intermediate and tolerant groupings were assessed in microtitre plate assays with increasing concentrations of lacticin 3147. The concentration of lacticin 3147 required to give 50% growth inhibition correlated with their relative sensitivities (as assayed by well diffusion methodology) and ranged from 1280 to 5120 AU ml(-1). Concentrated preparations of lacticin 3147 caused a rapid killing of Strep. mutans strains in broth. Moreover, in human saliva deliberately spiked with Strep. mutans, the pathogen was eliminated (initial inoculum of 10(5)) in the presence of 40,000 AU ml(-1) of lacticin 3147. Furthermore, a food-grade lacticin 3147 spray dried powder ingredient was assessed for the inhibition of Strep. mutans in human saliva, spiked with a strain of intermediate sensitivity, resulting in up to a 4-log reduction in counts after 20 min. CONCLUSION: A food grade preparation of lacticin 3147 was effective in the inhibition of oral Strep. mutans. SIGNIFICANCE AND IMPACT OF THE STUDY: The inhibition of oral streptococci by food grade preparations of lacticin 3147 may offer novel opportunities for the development of lacticin 3147 as an anti-cariogenic agent particularly in the area of functional foods for the improvement of oral health.