The roles of the preproghrelin-derived peptides - ghrelin, desacyl ghrelin and obestatin - in prostate cancer

Prostate cancer is the second most common cause of cancer related deaths in Western men. Despite the significant improvements in current treatment techniques, there is no cure for advanced metastatic, castrate-resistant disease. Early detection and prevention of progression to a castrate-resistant state may provide new strategies to improve survival. A number of growth factors have been shown to act in an autocrine/paracrine manner to modulate prostate cancer tumour growth. Our laboratory has previously shown that ghrelin and its receptors (the functional GHS-R1a and the non-functional GHS-R1b) are expressed in prostate cancer specimens and cell lines. We have shown that ghrelin increases cell proliferation in the PC3 and LNCaP prostate cancer cell lines through activation of ERK1/2, suggesting that ghrelin could regulate prostate cancer cell growth and play a role in the progression of the disease. Ghrelin is a 28 amino-acid peptide hormone, identified to be the natural ligand of the growth hormone secretagogue receptor (GHS-R1a). It is well characterised as a growth hormone releasing and as an orexigenic peptide that stimulates appetite and feeding and regulates energy expenditure and bodyweight. In addition to its orexigenic properties, ghrelin has been shown to play a regulatory role in a number of systems, including the reproductive, immune and cardiovascular systems and may play a role in a number of pathological conditions such as chronic heart failure, anorexia, cachexia, obesity, diabetes and cancer. In cancer, ghrelin and its receptor are expressed in a range of tumours and cancer cell lines and ghrelin has been demonstrated to modulate cell proliferation, apoptosis, migration and invasion in some cell types. The ghrelin gene (GHRL) encodes preproghrelin peptide, which is processed to produce three currently known functional peptides - ghrelin, desacyl ghrelin and obestatin. Prohormone convertases (PCs) have been shown to cleave the preproghrelin peptide into two primary products - the 28 amino acid peptide, ghrelin, and the remaining 117 amino acid C-terminal peptide, C-ghrelin. C-ghrelin can then be further processed to produce the 23 amino acid peptide, obestatin. Ghrelin circulates in two different forms - an octanoylated form (known as ghrelin) and a non-octanoylated form, desacyl ghrelin. The unique post-translational addition of octanoic acid to the serine 3 residue of the propeptide chain to form acylated ghrelin is catalysed by ghrelin O-acyltransferase (GOAT). This modification is necessary for binding of ghrelin to its only known functional receptor, the GHS-R1a. As desacyl ghrelin cannot bind and activate the GHS-R1a, it was initially thought to be an inactive peptide, despite the fact that it circulates at much higher levels than ghrelin. Further research has demonstrated that desacyl ghrelin is biologically active and shares some of the actions of ghrelin, as well as having some opposing and distinct roles. Interestingly, both ghrelin and desacyl ghrelin have been shown to modulate apoptosis, cell differentiation and proliferation in some cell types, and to stimulate cell proliferation through activation of ERK1/2 and PI3K/Akt pathways. The third known peptide product of the ghrelin preprohormone, obestatin, was initially thought to oppose the actions of ghrelin in appetite regulation and food intake and to mediate its effects through the G protein-coupled receptor 39 (GPR39). Subsequent research failed to reproduce the initial findings, however, and the possible anorexigenic effects of obestatin, as well as the identity of its receptor, remain unclear. Obestatin plays some important physiological roles, including roles in improving memory, the inhibition of thirst and anxiety, increased secretion of pancreatic juice, and regulation of cell proliferation, survival, apoptosis and differentiation. Preliminary studies have also shown that obestatin stimulates cell proliferation in some cell types through activation of ERK1/2, Akt and PKC pathways. Overall, however, at the commencement of this PhD project, relatively little was known regarding the functions and mechanisms of action of the preproghrelin-derived functional peptides in modulating prostate cancer cell proliferation. The roles of obestatin, and desacyl ghrelin as potential growth factors had not previously been investigated, and the potential expression and regulation of the preproghrelin processing enzymes, GOAT and prohormone convertases was unknown in prostate cancer cell lines. Therefore, the overall objectives of this study were to: 1. investigate the effects of obestatin on cell proliferation and signaling in prostate cancer cell lines 2. compare the effects of desacyl ghrelin and ghrelin on cell proliferation and signaling in prostate cancer cell lines 3. investigate whether prostate cancer cell lines possess the necessary enzymatic machinery to produce ghrelin and desacyl ghrelin and if these peptides can regulate GOAT expression Our laboratory has previously shown that ghrelin stimulates cell proliferation in the PC3 and LNCaP prostate cancer cell line through activation of the ERK1/2 pathway. In this study it has been demonstrated that treatments with either ghrelin, desacyl ghrelin or obestatin over 72 hours significantly increased cell proliferation in the PC3 prostate cancer cell line but had no significant effect in the RWPE-1 transformed normal prostate cell line. Ghrelin (1000nM) stimulated cell proliferation in the PC3 prostate cancer cell line by 31.66 6.68% (p<0.01) with the WST-1 method, and 13.55 5.68% (p<0.05) with the CyQUANT assay. Desacyl ghrelin (1000nM) increased cell proliferation in PC3 cells by 21.73 2.62% (p<0.01) (WST-1), and 15.46 7.05% (p<0.05) (CyQUANT) above untreated control. Obestatin (1000nM) induced a 28.37 7.47% (p<0.01) (WST-1) and 12.14 7.47% (p<0.05) (CyQUANT) significant increase in cell proliferation in the PC3 prostate cancer cell line. Ghrelin and desacyl ghrelin treatments stimulated Akt and ERK phosphorylation across a range of concentrations (p<0.01). Obestatin treatment significantly stimulated Akt, ERK and PKC phosphorylation (p<0.05). Through the use of specific inhibitors, the MAPK inhibitor U0126 and the Akt1/2 kinase inhibitor, it was demonstrated that ghrelin- and obestatin-induced cell proliferation in the PC3 prostate cancer cell line is mediated through activation of ERK1/2 and Akt pathways. Although desacyl ghrelin significantly stimulated Akt and ERK phosphorylation, U0126 failed to prevent desacyl ghrelin-induced cell proliferation suggesting ghrelin and desacyl ghrelin might act through different mechanisms to increase cell proliferation. Ghrelin and desacyl ghrelin have shown a proliferative effect in osteoblasts, pancreatic -cells and cardiomyocytes through activation of ERK1/2 and PI3K/Akt pathways. Here it has been shown that ghrelin and its non-acylated form exert the same function and stimulate cell proliferation in the PC3 prostate cancer cell line through activation of the Akt pathway. Ghrelin-induced proliferation was also mediated through activation of the ERK1/2 pathway, however, desacyl ghrelin seems to stimulate cell proliferation in an ERK1/2-independent manner. As desacyl ghrelin does not bind and activate GHSR1a, the only known functional ghrelin receptor, the finding that both ghrelin and desacyl ghrelin stimulate cell proliferation in the PC3 cell line suggests that these peptides could be acting through the yet unidentified alternative ghrelin receptor in this cell type. Obestatin treatment also stimulated PKC phosphorylation, however, a direct role for this pathway in stimulating cell proliferation could not be proven using available PKC pathway inhibitors, as they caused significant cell death over the extended timeframe of the cell proliferation assays. Obestatin has been shown to stimulate cell proliferation through activation of PKC isoforms in human retinal epithelial cells and in the human gastric cancer cell line KATO-III. We have demonstrated that all of the prostate-derived cell lines examined (PC3, LNCaP, DU145, 22Rv1, RWPE-1 and RWPE-2) expressed GOAT and at least one of the prohormone convertases, which are known to cleave the proghrelin peptide, PC1/3, PC2 and furin, at the mRNA level. These cells, therefore, are likely to possess the necessary machinery to cleave the preproghrelin protein and to produce the mature ghrelin and desacyl ghrelin peptides. In addition to prohormone convertases, the presence of octanoic acid is essential for acylated ghrelin production. In this study octanoic acid supplementation significantly increased cell proliferation in the PC3 prostate cancer cell line by over 20% compared to untreated controls (p<0.01), but surprisingly, not in the DU145, LNCaP or 22Rv1 prostate cancer cell lines or in the RWPE-1 and RWPE-2 prostate-derived cell lines. In addition, we demonstrated that exogenous ghrelin induced a statistically significant two-fold decrease in GOAT mRNA expression in the PC3 cell line (p<0.05), suggesting that ghrelin could pontentially downregulate its own acylation and, therefore, regulate the balance between ghrelin and desacyl ghrelin. This was not observed, however, in the DU145 and LNCaP prostate cancer cell lines. The GOAT-ghrelin system represents a direct link between ingested nutrients and regulation of ghrelin production and the ghrelin/desacyl ghrelin ratio. Regulation of ghrelin acylation is a potentially attractive and desirable tool for the development of better therapies for a number of pathological conditions where ghrelin has been shown to play a key role. The finding that desacyl ghrelin stimulates cell proliferation in the PC3 prostate cancer cell line, and responds to ghrelin in the same way, suggests that this cell line expresses an alternative ghrelin receptor. Although all the cell lines examined expressed both GHS-R1a and GHS-R1b mRNA, it remains uncertain whether these cell lines express the unidentified alternative ghrelin receptor. It is possible that the varied responses seen could be due to the expression of different ghrelin receptors in different cell lines. In addition to GOAT, prohormone convertases and octanoic acid availability may regulate the production of different peptides from the ghrelin preprohormone. The studies presented in this thesis provide significant new information regarding the roles and mechanisms of action of the preproghrelin-derived peptides, ghrelin, desacyl ghrelin and obestatin, in modulating prostate cancer cell line proliferation. A number of key questions remain to be resolved, however, including the identification of the alternative ghrelin/desacyl ghrelin receptor, the identification of the obestatin receptor, a clarification of the signaling mechanisms which mediate cell proliferation in response to obestatin treatment and a better understanding of the regulation at both the gene and post-translational levels of functional peptide generation. Further studies investigating the role of the ghrelin axis using in vivo prostate cancer models may be warranted. Until these issues are determined, the potential for the ghrelin axis, to be recognised as a novel useful target for therapy for cancer or other pathologies will be uncertain.

Maternal correlates of maternal child feeding practices : a systematic review

Establishing healthy eating habits early in life is one important strategy to combat childhood obesity. Given that early maternal child feeding practices have been linked to child food intake and weight, identifying the maternal correlates of maternal child feeding practices is important in order to understand the determinants of childhood obesity; this was the overall aim of the current review. Academic databases were searched for studies examining the relationship between maternal child feeding practices and parenting, personal characteristics and psychopathology of mothers with preschoolers. Papers were limited to those published in English, between January 2000 - June 2012. Only studies with mothers of normally developing children between the ages of 2 - 6 years were included. There were no restrictions regarding the inclusion of maternal nationality or SES. Seventeen eligible studies were sourced. Information on the aim, sample, measures and findings of these was summarised into tables. The findings of this review support a relationship between maternal controlling parenting, general and eating psychopathology, and socioeconomic status and maternal child feeding practices. The main methodological issues of the studies reviewed included inconsistency in measures of maternal variables across studies and cross-sectional designs. We conclude that the maternal correlates associated with maternal child feeding practices are complex, and the pathways by which maternal correlates impact these feeding practices require further investigation.

Locomotor activation by theacrine, a purine alkaloid structurally similar to caffeine : involvement of adenosine and dopamine receptors

Purine compounds, such as caffeine, have many health-promoting properties and have proven to be beneficial in treating a number of different conditions. Theacrine, a purine alkaloid structurally similar to caffeine and abundantly present in Camellia kucha, has recently become of interest as a potential therapeutic compound. In the present study, theacrine was tested using a rodent behavioral model to investigate the effects of the drug on locomotor activity. Long Evans rats were injected with theacrine (24 or 48 mg/kg, i.p.) and activity levels were measured. Results showed that the highest dose of theacrine (48 mg/kg, i.p.) significantly increased locomotor activity compared to control animals and activity remained elevated throughout the duration of the session. To test for the involvement of adenosine receptors underlying theacrine's motor-activating properties, rats were administered a cocktail of the adenosine A₁ agonist, N⁶-cyclopentyladenosine (CPA; 0.1 mg/kg, i.p.) and A(2A) receptor agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS-21680; 0.2 mg/kg, i.p.). Pre-treatment with theacrine significantly attenuated the motor depression induced by the adenosine receptor agonists, indicating that theacrine is likely acting as an adenosine receptor antagonist. Next, we examined the role of DA D₁ and D₂ receptor antagonism on theacrine-induced hyperlocomotion. Both antagonists, D₁R SCH23390 (0.1 or 0.05 mg/kg, i.p.) and D₂R eticlopride (0.1 mg/kg, i.p.), significantly reduced theacrine-stimulated activity indicating that this behavioral response, at least in part, is mediated by DA receptors. In order to investigate the brain region where theacrine may be acting, the drug (10 or 20 μg) was infused bilaterally into nucleus accumbens (NAc). Theacrine enhanced activity levels in a dose-dependent manner, implicating a role of the NAc in modulating theacrine's effects on locomotion. In addition, theacrine did not induce locomotor sensitization or tolerance after chronic exposure. Taken together, these findings demonstrate that theacrine significantly enhances activity; an effect which is mediated by both the adenosinergic and dopaminergic systems.

A human-simulated immune evolutionary computation approach

Premature convergence to local optimal solutions is one of the main difficulties when using evolutionary algorithms in real-world optimization problems. To prevent premature convergence and degeneration phenomenon, this paper proposes a new optimization computation approach, human-simulated immune evolutionary algorithm (HSIEA). Considering that the premature convergence problem is due to the lack of diversity in the population, the HSIEA employs the clonal selection principle of artificial immune system theory to preserve the diversity of solutions for the search process. Mathematical descriptions and procedures of the HSIEA are given, and four new evolutionary operators are formulated which are clone, variation, recombination, and selection. Two benchmark optimization functions are investigated to demonstrate the effectiveness of the proposed HSIEA.

Bicep femoris voluntary activation deficits contribute to eccentric knee flexor weakness following intermittent running

INTRODUCTION: Hamstring strain injuries (HSI) are the predominant non-contact injury in many sports. Eccentric hamstring muscle weakness following intermittent running has been implicated within the aetiology of HSI. This weakness following intermittent running is often greater eccentrically than concentrically, however the cause of this unique, contraction mode specific phenomenon is unknown. AIM: To determine if this preferential eccentric decline in strength is caused by declines in voluntary hamstring muscle activation. METHODS: Fifteen recreationally active males completed 18 × 20m overground sprints. Maximal strength (concentric and eccentric knee flexor and concentric knee extensor) was determined isokinetically at the velocities of ±1800.s-1 and ±600.s- while hamstring muscle activation was assessed using surface electromyography, before and 15 minutes after the running protocol. RESULTS: Overground intermittent running caused greater eccentric (27.2 Nm; 95% CI = 11.2 to 43.3; p=0.0001) than concentric knee flexor weakness (9.3 Nm; 95% CI = -6.7 to 25.3; P=0.6361). Following the overground running, voluntary activation levels of the lateral hamstrings showed a significant decline (0.08%; 95% CI = 0.045 to 0.120; P<0.0001). In comparison, medial hamstring activation showed no change following intermittent running. CONCLUSION: Eccentric hamstring strength is decreased significantly following intermittent overground running. Voluntary activation deficits in the biceps femoris muscle are responsible for some portion of this weakness. The implications of this finding are significant because the biceps femoris muscle is the most frequently strained of all the hamstring muscles and because fatigue appears to play an important part in injury occurrence.

Do voluntary activation deficits contribute to eccentric weakness following intermittent running?

Hamstring strain injuries (HSI) are the predominant non-contact injury in many sports. Eccentric hamstring muscle weakness following intermittent running has been implicated within the aetiology of HSI. This weakness following intermittent running is often greater eccentrically than concentrically, however the cause of this unique, contraction mode specific phenomenon is unknown. PURPOSE: To determine if this preferential eccentric decline in strength is caused by declines in voluntary hamstring muscle activation. METHODS: Fifteen recreationally active males completed 18 × 20m overground sprints. Maximal strength (concentric and eccentric knee flexor and concentric knee extensor) was determined isokinetically at the velocities of ±1800.s-1 and ±600.s- while hamstring muscle activation was assessed using surface electromyography, before and 15 minutes after the running protocol. RESULTS: Overground intermittent running caused greater eccentric (27.2 Nm; 95% CI = 11.2 to 43.3; p=0.0001) than concentric knee flexor weakness (9.3 Nm; 95% CI = -6.7 to 25.3; P=0.6361). Following the overground running, voluntary activation levels of the lateral hamstrings showed a significant decline (0.08%; 95% CI = 0.045 to 0.120; P<0.0001). In comparison, medial hamstring activation showed an increased level of activation following intermittent running (0.12%; 95% CI = 0.049 to 0.030; P = 0.0102). CONCLUSION: Eccentric hamstring strength is decreased significantly following intermittent overground running. Voluntary activation deficits in the biceps femoris muscle are responsible for some portion of this weakness. The implications of this finding are significant because the biceps femoris muscle is the most frequently strained of all the hamstring muscles and because fatigue appears to play an important part in injury occurrence.

Declines in eccentric knee flexor weakness following repeat sprint running are related to declines in biceps femoris voluntary activation

Introduction: Hamstring strain injuries (HSI) are the predominant non-contact injury in many sports. Eccentric hamstring muscle weakness following intermittent running has been implicated within the aetiology of HSI. This weakness following intermittent running is sometimes greater eccentrically than concentrically, however the cause of this unique, contraction mode specific phenomenon is unknown. The purpose of this research was to determine whether declines in knee flexor strength following overground repeat sprints are caused by declines in voluntary activation of the hamstring muscles. Methods: Seventeen recreationally active males completed 3 sets of 6 by 20m overground sprints. Maximal isokinetic concentric and eccentric knee flexor and concentric knee extensor strength was determined at ±1800.s-1 and ±600.s-1 while hamstring muscle activation was assessed using surface electromyography, before and 15 minutes after the running protocol. Results: Overground repeat sprint running resulted in a significant decline in eccentric knee flexor strength (31.1 Nm; 95% CI = 21.8 to 40.3 Nm; p < 0.001). However, concentric knee flexor strength was not significantly altered (11.1 Nm; 95% CI= -2.8 to 24.9; p=0.2294). Biceps femoris voluntary activation levels displayed a significant decline eccentrically (0.067; 95% CI=0.002 to 0.063; p=0.0325). However, there was no significant decline concentrically (0.025; 95% CI=-0.018 to 0.043; p=0.4243) following sprinting. Furthermore, declines in average peak torque at -1800.s-1 could be explained by changes in hamstring activation (R2 = 0.70). Moreover, it was change in the lateral hamstring muscle activity that was related to the decrease in knee flexor torque (p = 0.0144). In comparison, medial hamstring voluntary activation showed no change for either eccentric (0.06; 95% CI = -0.033 to 0.102; p=0.298) or concentric (0.09; 95% CI = -0.03 to 0.16; p=0.298) muscle actions following repeat sprinting. Discussion: Eccentric hamstring strength is decreased significantly following overground repeat sprinting. Voluntary activation deficits in the biceps femoris muscle explain a large portion of this weakness. The implications of these findings are significant as the biceps femoris muscle is the most frequently strained of the knee flexors and fatigue is implicated in the aetiology of this injury.

Knee flexor strength and biceps femoris activation deficits following hamstring strain injury

Background: Hamstring strain injuries (HSI) are prevalent in sport and re-injury rates have been high for many years. Maladaptation following HSI are implicated in injury recurrence however nervous system function following HSI has received little attention. Aim: To determine if recreational athletes with a history of unilateral HSI, who have returned to training and competition, will exhibit lower levels of voluntary activation (VA) and median power frequency (MPF) in the previously injured limb compared to the uninjured limb at long muscle lengths. Methods: Twenty-eight recreational athletes were recruited. Of these, 13 athletes had a history of unilateral HSI and 15 had no history of HSI. Following familiarisation, all athletes undertook isokinetic dynamometry testing and surface electromyography assessment of the biceps femoris long head and medial hamstrings during concentric and eccentric contractions at ± 180 and ± 60deg/s. Results: The previously injured limb was weaker at all contraction speeds compared to the uninjured limb (+180deg/s mean difference(MD) = 9.3Nm, p = 0.0036; +60deg/s MD = 14.0Nm, p = 0.0013; -60deg/s MD = 18.3Nm, p = 0.0007; -180deg/s MD = 20.5Nm, p = 0.0007) whilst VA was only lower in the biceps femoris long head during eccentric contractions (-60deg/s MD = 0.13, p = 0.0025; -180deg/s MD = 0.13, p = 0.0003). There were no between limb differences in medial hamstring VA or MPF from either biceps femoris long head or medial hamstrings in the injured group. The uninjured group showed no between limb differences with any of the tested variables. Conclusion: Previously injured hamstrings were weaker than the contralateral uninjured hamstring at all tested speeds and contraction modes. During eccentric contractions biceps femoris long head VA was lower in the previously injured limb suggesting neural control of biceps femoris long head may be altered following HSI. Current rehabilitation practices have been unsuccessful in restoring strength and VA following HSI. Restoration of these markers should be considered when determining the success of rehabilitation from HSI. Further investigations are required to elucidate the full impact of lower levels of biceps femoris long head VA following HSI on rehabilitation outcomes and re-injury risk.

Human immunodeficiency virus type 1 subtype C Gag virus-like particle boost substantially improves the immune response to a subtype C gag DNA vaccine in mice

Human immunodeficiency virus type 1 (HIV-1) subtype C is the predominant HIV in southern Africa, and is the target of a number of recent vaccine candidates. It has been proposed that a heterologous prime/boost vaccination strategy may result in stronger, broader and more prolonged immune responses. Since HIV-1 Gag Pr55 polyprotein can assemble into virus-like particles (VLPs) which have been shown to induce a strong cellular immune response in animals, we showed that a typical southern African subtype C Pr55 protein expressed in insect cells via recombinant baculovirus could form VLPs. We then used the baculovirus-produced VLPs as a boost to a subtype C HIV-1 gag DNA prime vaccination in mice. This study shows that a low dose of HIV-1 subtype C Gag VLPs can significantly boost the immune response to a single subtype C gag DNA inoculation in mice. These results suggest a possible vaccination regimen for humans. © 2004 SGM.

HIV-1 sub-type C chimaeric VLPs boost cellular immune responses in mice

Several approaches have been explored to eradicate HIV; however, a multigene vaccine appears to be the best option, given their proven potential to elicit broad, effective responses in animal models. The Pr55 Gagprotein is an excellent vaccine candidate in its own right, given that it can assemble into large, enveloped, virus-like particles (VLPs) which are highly immunogenic, and can moreover be used as a scaffold for the presentation of other large non-structural HIV antigens. In this study, we evaluated the potential of two novel chimaeric HIV-1 Pr55 Gag-based VLP constructs - C-terminal fusions with reverse transcriptase and a Tat::Nef fusion protein, designated GagRT and GagTN respectively - to enhance a cellular response in mice when used as boost components in two types of heterologous prime-boost vaccine strategies. A vaccine regimen consisting of a DNA prime and chimaeric HIV-1 VLP boosts in mice induced strong, broad cellular immune responses at an optimum dose of 100 ng VLPs. The enhanced cellular responses induced by the DNA prime-VLP boost were two- to three-fold greater than two DNA vaccinations. Moreover, a mixture of GagRT and GagTN VLPs also boosted antigen-specific CD8+ and CD4+ T-cell responses, while VLP vaccinations only induced predominantly robust Gag CD4+ T-cell responses. The results demonstrate the promising potential of these chimaeric VLPs as vaccine candidates against HIV-1. © 2010 Pillay et al; licensee BioMed Central Ltd.

Toddlers’ food preferences : the impact of novel food exposure, maternal preferences and food neophobia

Food preferences have been identified as a key determinant of children’s food acceptance and consumption. The aim of this study was to identify factors that influence children’s liking for fruits, vegetables and non-core foods. Participants were Australian mothers (median age at delivery=31 years, 18-46 years) and their two-year-old children (M=25 months, SD=1 month; 52% female) allocated to the control group (N=230) of the NOURISH RCT. The effects of repeated exposure to new foods, maternal food preferences and child food neophobia on toddlers’ liking of vegetables, fruits and non-core foods and the proportion never tried were examined via hierarchical regression models; adjusting for key maternal (age, BMI, education) and child covariates (birth weight Z-score, gender), duration of breastfeeding and age of introduction to solids. Maternal preferences corresponded with child preferences. Food neophobia among toddlers was associated with liking fewer vegetables and fruits, and trying fewer vegetables. Number of repeated exposures to new food was not significantly associated with food liking at this age. Results highlight the need to: (i) encourage parents to offer a wide range of foods, regardless of their own food preferences, and (ii) provide parents with guidance on managing food neophobia.

Peripheral compartment innate immune response to Haemophilus influenzae and Streptococcus pneumoniae in chronic obstructive pulmonary disease patients.

Alterations in innate immunity that predispose to chronic obstructive pulmonary disease (COPD) exacerbations are poorly understood. We examined innate immunity gene expression in peripheral blood polymorphonuclear leukocytes (PMN) and monocytes stimulated by Haemophilus influenzae and Streptococcus pneumoniae. Thirty COPD patients (15 rapid and 15 non-rapid lung function decliners) and 15 smokers without COPD were studied. Protein expression of IL-8, IL-6, TNF-α and IFN-γ (especially monocytes) increased with bacterial challenge. In monocytes stimulated with S. pneumoniae, TNF-α protein expression was higher in COPD (non-rapid decliners) than in smokers. In co-cultures of monocytes and PMN, mRNA expression of TGF-β1 and MYD88 was up-regulated, and CD14, TLR2 and IFN-γ down-regulated with H. influenzae challenge. TNF-α mRNA expression was increased with H. influenzae challenge in COPD. Cytokine responses were similar between rapid and non-rapid decliners. TNF-α expression was up-regulated in non-rapid decliners in response to H. influenzae (monocytes) and S. pneumoniae (co-culture of monocytes and PMN). Exposure to bacterial pathogens causes characteristic innate immune responses in peripheral blood monocytes and PMN in COPD. Bacterial exposure significantly alters the expression of TNF-α in COPD patients, although not consistently. There did not appear to be major differences in innate immune responses between rapid and non-rapid decliners.

How activation, entanglement, and searching a semantic network contribute to event memory

Free association norms indicate that words are organized into semantic/associative neighborhoods within a larger network of words and links that bind the net together. We present evidence indicating that memory for a recent word event can depend on implicitly and simultaneously activating related words in its neighborhood. Processing a word during encoding primes its network representation as a function of the density of the links in its neighborhood. Such priming increases recall and recognition and can have long lasting effects when the word is processed in working memory. Evidence for this phenomenon is reviewed in extralist cuing, primed free association, intralist cuing, and single-item recognition tasks. The findings also show that when a related word is presented to cue the recall of a studied word, the cue activates it in an array of related words that distract and reduce the probability of its selection. The activation of the semantic network produces priming benefits during encoding and search costs during retrieval. In extralist cuing recall is a negative function of cue-to-distracter strength and a positive function of neighborhood density, cue-to-target strength, and target-to cue strength. We show how four measures derived from the network can be combined and used to predict memory performance. These measures play different roles in different tasks indicating that the contribution of the semantic network varies with the context provided by the task. We evaluate spreading activation and quantum-like entanglement explanations for the priming effect produced by neighborhood density.