Maria Viskaduraki

Cancer chemoprevention: Evidence of a nonlinear dose response for the protective effects of resveratrol in humans and mice

Low-dose resveratrol prevents tumor growth in mice and in human tissues, suggesting a revision of development strategies for preventive dietary agents. Less is more From energy drinks to supplements to skin serums, resveratrol has been sold to the public for myriad health benefits, most famously in the anti-aging arena. In fact, at a posh wine bar, one might overhear a patron lamenting the small dose of resveratrol one receives in a glass of the red variety. Now, Cai et al. show that a low rather than a high dose of resveratrol prevents tumor growth in mice and alters metabolic pathways in human tissues. The authors compared the dose-response curves of a dietary dose of resveratrol and a 200-fold higher amount in mice that spontaneously develop colorectal adenomas—precursors to cancer—that were fed a standard or a high-fat diet. In the mice on the high-fat diet, low-dose resveratrol reduced intestinal tumor development much better than did the high dose. In mouse tumor cells, resveratrol efficacy was tracked with an increase in autophagy and senescence markers and activation of adenosine monophosphate (AMP)–activated protein kinase (AMPK)—an enzyme that functions in the maintenance of cellular energy homeostasis. Exposure of human colorectal cancer tissue to low concentrations of resveratrol also caused an increase in autophagy and activation of AMPK. Colorectal mucosal samples isolated from cancer patients who received a low-dose resveratrol regimen before tumor resection showed an increase in expression of the cytoprotective, oxidative stress-activated enzyme NAD(P)H dehydrogenase, quinone 1 (NQO1). These findings suggest that resveratrol operates by modulating energy balance and responding to stress. At a time when “supersizing” is popular, the nonlinear dose-response documented in the new work suggests that its time for a revision in development strategies for preventative dietary agents. Resveratrol is widely promoted as a potential cancer chemopreventive agent, but a lack of information on the optimal dose prohibits rationally designed trials to assess efficacy. To challenge the assumption that “more is better,” we compared the pharmacokinetics and activity of a dietary dose with an intake 200 times higher. The dose-response relationship for concentrations generated and the metabolite profile of [14C]-resveratrol in colorectal tissue of cancer patients helped us to define clinically achievable levels. In ApcMin mice (a model of colorectal carcinogenesis) that received a high-fat diet, the low resveratrol dose suppressed intestinal adenoma development more potently than did the higher dose. Efficacy correlated with activation of adenosine monophosphate–activated protein kinase (AMPK) and increased expression of the senescence marker p21. Nonlinear dose responses were observed for AMPK and mechanistic target of rapamycin (mTOR) signaling in mouse adenoma cells, culminating in autophagy and senescence. In human colorectal tissues exposed to low dietary concentrations of resveratrol ex vivo, we measured enhanced AMPK phosphorylation and autophagy. The expression of the cytoprotective NAD(P)H dehydrogenase, quinone 1 (NQO1) enzyme was also increased in tissues from cancer patients participating in our [14C]-resveratrol trial. These findings warrant a revision of developmental strategies for diet-derived agents designed to achieve cancer chemoprevention.

Phosphoproteomics reveals malaria parasite Protein Kinase G as a signalling hub regulating egress and invasion

Our understanding of the key phosphorylation-dependent signalling pathways in the human malaria parasite, Plasmodium falciparum, remains rudimentary. Here we address this issue for the essential cGMP-dependent protein kinase, PfPKG. By employing chemical and genetic tools in combination with quantitative global phosphoproteomics, we identify the phosphorylation sites on 69 proteins that are direct or indirect cellular targets for PfPKG. These PfPKG targets include proteins involved in cell signalling, proteolysis, gene regulation, protein export and ion and protein transport, indicating that cGMP/PfPKG acts as a signalling hub that plays a central role in a number of core parasite processes. We also show that PfPKG activity is required for parasite invasion. This correlates with the finding that the calcium-dependent protein kinase, PfCDPK1, is phosphorylated by PfPKG, as are components of the actomyosin complex, providing mechanistic insight into the essential role of PfPKG in parasite egress and invasion.

β-defensin Genomic Copy Number Is Associated With HIV Load and Immune Reconstitution in Sub-Saharan Africans

AIDS, caused by the retrovirus human immunodeficiency virus (HIV), is the leading cause of death of economically active people (age, 15-59 years) in sub-Saharan Africa. The host genetic variability of immune response to HIV and immune reconstitution following initiation of highly active antiretroviral therapy (HAART) is poorly understood. Here we focused on copy number variation of the β-defensin genes, which have been shown to have anti-HIV activity, and are important chemoattractants for Th17 lymphocytes via the chemokine receptor CCR6. We determined β-defensin gene copy number for 1002 Ethiopian and Tanzanian patients. We show that higher β-defensin copy number variation is associated with increased HIV load prior to HAART (P=.005) and poor immune reconstitution following initiation of HAART (P=.003). We suggest a model where variable amounts of β-defensin expression by mucosal cells, due to gene copy number variation, alters the efficacy of recruitment of Th17 lymphocytes to the site of infection, altering the dynamics of infection.

CCL3L1 copy number, HIV load, and immune reconstitution in sub-Saharan Africans

BackgroundThe role of copy number variation of the CCL3L1 gene, encoding MIP1α, in contributing to the host variation in susceptibility and response to HIV infection is controversial. Here we analyse a sub-Saharan African cohort from Tanzania and Ethiopia, two countries with a high prevalence of HIV-1 and a high co-morbidity of HIV with tuberculosis.MethodsWe use a form of quantitative PCR called the paralogue ratio test to determine CCL3L1 gene copy number in 1134 individuals and validate our copy number typing using array comparative genomic hybridisation and fiber-FISH.ResultsWe find no significant association of CCL3L1 gene copy number with HIV load in antiretroviral-naïve patients prior to initiation of combination highly active anti-retroviral therapy. However, we find a significant association of low CCL3L1 gene copy number with improved immune reconstitution following initiation of highly active anti-retroviral therapy (p = 0.012), replicating a previous study.ConclusionsOur work supports a role for CCL3L1 copy number in immune reconstitution following antiretroviral therapy in HIV, and suggests that the MIP1α -CCR5 axis might be targeted to aid immune reconstitution.

Copy number variation of Fc gamma receptor genes in HIV-infected and HIV-tuberculosis co-infected individuals in sub-Saharan Africa

AIDS, caused by the retrovirus HIV, remains the largest cause of morbidity in sub-Saharan Africa yet almost all genetic studies have focused on cohorts from Western countries. HIV shows high co-morbidity with tuberculosis (TB), as HIV stimulates the reactivation of latent tuberculosis (TB). Recent clinical trials suggest that an effective anti-HIV response correlates with non-neutralising antibodies. Given that Fcγ receptors are critical in mediating the non-neutralising effects of antibodies, analysis of the extensive variation at Fcγ receptor genes is important. Single nucleotide variation and copy number variation (CNV) of Fcγ receptor genes affects the expression profile, activatory/inhibitory balance, and IgG affinity of the Fcγ receptor repertoire of each individual. In this study we investigated whether CNV of FCGR2C, FCGR3A and FCGR3B as well as the HNA1 allotype of FCGR3B is associated with HIV load, response to highly-active antiretroviral therapy (HAART) and co-infection with TB. We confirmed an effect of TB-co-infection status on HIV load and response to HAART, but no conclusive effect of the genetic variants we tested. We observed a small effect, in Ethiopians, of FCGR3B copy number, where deletion was more frequent in HIV-TB co-infected patients than those infected with HIV alone.

Pneumococcal polysaccharide vaccine responses are impaired in a subgroup of children with cystic fibrosis

BACKGROUND Pneumococcal immunization is recommended in children with cystic fibrosis (CF). To date, however, there are no published studies on the efficacy of pneumococcal vaccination in this group of patients. METHODS We carried out a retrospective study of serotype-specific pneumococcal antibody responses to immunization with Prevenar 7 and Pneumovax II in a cohort of children with CF. RESULTS Nine children had been immunized with Prevenar 7, and all had serotype-specific pneumococcal antibody levels in the protective range (>0.35mg/L) to all 7 immunizing serotypes. In contrast, only 7 of 33 patients (21%) immunized with Pneumovax II made protective antibody responses to all 7 serotypes, and 3 failed to make protective antibodies to any of the serotypes. Controlling for age as a confounder in the analysis, children with impaired antibody responses to pneumococcal polysaccharide (Pneumovax II) immunization had lower Shwachman-Kulczycki scores than children with normal polysaccharide antibody responses. All isolates of Pseudomonas aeruginosa occurred in patients with impaired anti-pneumococcal antibody responses, and a broader range of respiratory pathogens was isolated from these children. CONCLUSIONS Impaired antibody responses to immunization with Pneumovax II are common in children with CF and this may be associated with increased disease severity.

The Validity of Fractional Excretion of Uric Acid in the Diagnosis of Acute Kidney Injury Due to Decreased Kidney Perfusion

1. Ashman N. Efficacy of sodium citrate antimicrobial ocks for reducing rates of catheter-related bacteremia [leter]. Am J Kidney Dis. 2009;54(6):1185. 2. Power A, Duncan N, Singh SK, et al. Sodium citrate ersus heparin catheter locks for cuffed central venous atheters: a single-center randomized controlled trial. Am J idney Dis. 2009;53(6):1034-1041. 3. Winnett G, Nolan J, Miller M, Ashman N. Trisodium itrate 46.7% selectively and safely reduces staphylococcal atheter-related bacteraemia. Nephrol Dial Transplant. 2008; 3(11):3592-3598. 4. Rabindranath KS, Bansal T, Adams J, et al. Systematic eview of antimicrobials for the prevention of haemodialysis atheter-related bacteraemia. Nephrol Dial Transplant. 2009; oi 10.1093/ndt/gfp327. 5. Bleyer AJ, Mason L, Russell G, et al. A randomised, ontrolled trial of a new vascular catheter flush solution minocycline-EDTA) in temporary haemodialysis access. nfect Control Hosp Epidemiol. 2005;26(6):520-524. 6. Zhang P, Zhang A, Qiang H, et al. A randomized ontrolled study on the prevention of cuff-tunneled catheter elated bacteremia with gentamicin-heparin locked solution abstract]. J Am Soc Nephrol. 2006;17:592A. 7. Zhang P, Yuan J, Tan H, et al. Successful prevention f cuffed hemodialysis catheter-related infection using an ntibiotic lock technique by strictly catheter-restricted ntibiotic lock solution method. Blood Purif. 2009;27(2): 06-211. 8. Power A, Duncan N, Singh SK, et al. Long-term, igh-adequacy haemodialysis can be delivered safely by esio-Caths [abstract]. J Am Soc Nephrol. 2008;19:905A.

P90 How does bmi status influence spirometry and respiratory muscle strength in children

Introduction While BMI correlates positively with spirometry during childhood, young children who are overweight or obese have been shown to have a reduced FEV1/FVC compared to their peers.1 In childhood, obesity has been shown to have a negative effect upon inspiratory muscle strength.2 Aims To assess whether there are differences in spirometry of children of varying BMI status and whether this relates to respiratory muscle strength. Methods Within schools, we measured each child’s height, weight, and spirometry. Respiratory muscle strength was assessed via maximal inspiratory and expiratory pressures (MIP/MEP). The child breathed through a pneumotachograph attached to a shutter. To measure MIP, the child exhaled maximally and the shutter was activated. The child made an inspiratory effort against the shutter and peak pressure was recorded. The test was repeated several times. Measurements of MEP were similar, except that the child inhaled maximally and then made a forceful expiratory effort. We calculated BMI and grouped children by centile score into underweight, healthy, overweight or obese, using epidemiological cut-offs. Results were adjusted for age and height via an ANCOVA. Results We studied 297 children (5–11 year). We obtained data for spirometry in 258, MIP in 231 and MEP in 262. Mean adjusted values are shown (Table). All individual parameters showed significant positive correlation with BMI, while FEV1/FVC was significantly negatively correlated with BMI. The obese group had a significantly greater adjusted mean value for MEP than the healthy group and a significantly greater mean adjusted value for FVC than the underweight group, while having a significantly lower mean adjusted FEV1/FVC than both healthy and underweight groups. Abstract P90 Table 1 Underweight Healthy Overweight Obese FEV1 (L) 1.55 1.69 1.69 1.67 FVC (L) 1.70 1.90 1.94 1.97 FEV1/FVC (%) 91.2 89.1 87.7 85.7 MIP (kPa) 6.89 7.07 7.68 7.57 MEP (kPa) 6.01 6.29 6.54 7.12 Conclusion Despite having the greatest adjusted mean value for expiratory muscle strength and vital capacity, the obese group demonstrated the lowest adjusted mean FEV1/FVC, indicating a potential alteration in respiratory flow dynamics for children of greater BMI. References Tantisira, et al. Thorax2003, Dec;58(12):1036–41. da Rosa, et al. Rev Paul Pediatr2014, Jun;32(2):250–5.

Strategic race blindness: not so black and white?

Purpose – Strategic race‐blindness (purposely avoiding mention of a targets ethnicity to appear unprejudiced) potentially hinders eyewitness testimony.Design/methodology/approach – The current study examined whether participant and interviewer race affected the recollection of black, white or Western Asian individuals, where it was indicated the targets were criminal or not. Data were gathered using a cognitive interview‐type methodology whereby stimulus questioning was open, rather than prompted. After a short interval participants spontaneously described the targets and the point at which race was used as a descriptor was noted.Findings – There was a clear effect of differential race mentioning in free recall by participants. However, multi‐level ordinal logistic regression found neither race of the interviewer nor race of the participant (or their interaction) influenced the mentioning of the race of the face in the photograph. This remained irrespective of the guilt of the person in the stimulus pict...