UK Food Standards Agency Workshop Report: Diet and Immune Function

The UK Food Standards Agency convened a workshop on 13 May 2009 to discuss recently completed research on diet and immune function. The objective of the workshop was to review this research and to establish priorities for future research. Several of the trials presented at the workshop showed some effect of nutritional interventions (e.g. vitamin D, Zn, Se) on immune parameters. One trial found that increased fruit and vegetable intake may improve the antibody response to pneumococcal vaccination in older people. The workshop highlighted the need to further clarify the potential public health relevance of observed nutrition-related changes in immune function, e.g. susceptibility to infections and infectious morbidity.

How does the short-wavelength-sensitive contrast sensitivity function for detection and resolution change with age in the periphery?

To determine the age-related change in the peripheral short-wavelength-sensitive (SWS) grating contrast sensitivity function (CSF), cut-off spatial frequency (acuity) and contrast sensitivity for both a detection and resolution task were measured at 8 degrees eccentricity under conditions of SWS-cone isolation for 51 subjects (19-72 years). The acuity for both the detection and resolution task declined with age, the detection acuity being significantly higher than the resolution acuity at all ages (p

Mid-infrared a-b plane response of YBa2Cu3O7-delta as a function of doping and temperature determined by attenuated total reflection

The mid-infrared optical response of c-axis thin films of YBa2Cu3O7-delta has been studied using Otto-configuration attenuated total reflectance. The measured reflectance-angle characteristics are dominated by a strong absorption feature due to the excitation of surface plasmons, and can be modeled to determine the a-b plane dielectric function. The results show that while epsilon(i,) and therefore sigma(r), are temperature independent, \epsilon(r)\ exhibits a moderate decrease with generalized Drude analysis shows that the plasma frequency is independent of temperature, but decreases with decreasing doping. The scattering rate increases with temperature, and also increases with decreasing doping, consistent with stronger coupling in the underdoped regime. The mass-enhancement is small but increases to 30-40% at delta = 0.6. Difficulties in reconciling the results with some current theories of high-T-c materials are discussed. Finally, the surface plasmon propagation lengths and penetration depths are shown to vary systematically with doping. (C) 2003 Elsevier B.V. All rights reserved.

The mid-infrared dielectric function of NBCO in the a-b plane from 85 K to 300 K

Results are reported on the a-b plane dielectric function (epsilon) of thin-film c-axis NdBa2Cu3O7-delta with close to optimal oxygen doping (T-c similar to 90 K) in the mid-infrared (wavelength 3.392 mum) over the temperature range 85 K to 300 K. An attenuated total reflectance technique based on the excitation of surface plasmon polaritons is used. The results show that \epsilon (r)\ decreases quasi-linearly with increasing temperature, while Ei is invariant with temperature to within experimental uncertainties. Representative values are epsilon = [epsilon (r) + i epsilon (i)] = (-12.9 +/- 0.6) + i(23.0 +/- 1.5) at T similar to 295 K and epsilon = (-15.7 +/- 0.7) + i(23.5 +/- 1.1) at T similar to 90 K. The raw data an interpreted in terms of the generalized Drude model which gives effective scattering rates (1/tau*) that increase with temperature from about 3800 cm(-1) at 90 K to about 4300 cm(-1) at 295 K. There are indications of a superlinear T-dependence in the scattering, 1/tau*: a fit to a function of the form 1/tau* = A + BTalpha gives alpha = 2.8 +/- 0.7. The effective plasma frequency, omega (p)*, with an average value of approximately 21 000 cm(-1) was independent of temperature.

Temperature dependence of the mid-infrared dielectric function of YBCO in the a-b plane: a re-evaluation

The a-b plane dielectric function (epsilon) of c-axis YBa2Cu3O7-delta thin films with T-c > 85 K was measured at lambda = 3.392 mum in the temperature range 85-300 It, using an attenuated total reflectance (ATR) technique based on the excitation of surface plasmons, The results show that \epsilon (r)\ decreases quasi-linearly with increasing temperature, while Ei is invariant to temperature within experimental uncertainties. Typical values are epsilon (ab) = -23 + 16.5i at similar to 295 R and epsilon (ab) = -27 + 15.5i at similar to 90 K. A generalised Drude analysis yields effective scattering rates (1/tau*) that increase with temperature from similar to 1500 to similar to 1900 cm(-1). The temperature dependent rates best fit an equation of the form 1/tau* = a + bT(alpha) with alpha = 1.46 +/- 0.40. The effective plasma frequencies of w(p)* similar to 18,500 cm(-1) are almost independent of temperature. The uniquely detailed temperature dependence of the results confirm and consolidate data obtained by other groups using normal reflectance methods, but contradict our previously published ATR measurements. Technical shortcomings in the earlier work are identified as the source of the discrepancy. (C) 2000 Elsevier Science B.V. All rights reserved.

Density-dependent prophylaxis and condition-dependent immune function in Lepidopteran larvae: a multivariate approach

1. The risk of parasitism and infectious disease is expected to increase with population density as a consequence of positive density-dependent transmission rates. Therefore, species that encounter large fluctuations in population density are predicted to exhibit plasticity in their immune system, such that investment in costly immune defences is adjusted to match the probability of exposure to parasites and pathogens (i.e. density-dependent prophylaxis).

Heritability of immune function in the caterpillar Spodoptera littoralis

Phenoloxidase (PO) is believed to be a key mediator of immune function in insects and has been implicated both in non-self recognition and in resistance to a variety of parasites and pathogens, including baculoviruses and parasitoids. Using larvae of the Egyptian cotton leafworm, Spodoptera littoralis, we found that despite its apparent importance, haemolymph PO activity varied markedly between individuals, even amongst insects reared under apparently identical conditions. Sib-analysis methods were used to determine whether individuals varied genetically in their PO activity, and hence in one aspect of immune function. The heritability estimate of haemolymph PO activity was high (h 2 = 0.690 +/- 0.069), and PO activity in the haemolymph was strongly correlated with PO activity in both the cuticle and midgut; the sites of entry for most parasites and pathogens. Haemolymph PO activity was also strongly correlated with the degree to which a synthetic parasite (a small piece of nylon monofilament) was encapsulated and melanized (r = 0.622 +/- 0.142), suggesting that the encapsulation response is also heritable. The mechanism maintaining this genetic variation has yet to be elucidated.

Testing the stability of the benefit transfer function for discrete choice contingent valuation data

This paper examines the stability of the benefit transfer function across 42 recreational forests in the British Isles. A working definition of reliable function transfer is Put forward, and a suitable statistical test is provided. A novel split sample method is used to test the sensitivity of the models' log-likelihood values to the removal of contingent valuation (CV) responses collected at individual forest sites, We find that a stable function improves Our measure of transfer reliability, but not by much. We conclude that, in empirical Studies on transferability, considerations of function stability are secondary to the availability and quality of site attribute data. Modellers' can study the advantages of transfer function stability vis-a-vis the value of additional information on recreation site attributes. (c) 2008 Elsevier GmbH. All rights reserved.

Combined R-matrix eigenstate basis set and finite-difference propagation method for the time-dependent Schrodinger equation: The one-electron case

In this work we present the theoretical framework for the solution of the time-dependent Schrödinger equation (TDSE) of atomic and molecular systems under strong electromagnetic fields with the configuration space of the electron’s coordinates separated over two regions; that is, regions I and II. In region I the solution of the TDSE is obtained by an R-matrix basis set representation of the time-dependent wave function. In region II a grid representation of the wave function is considered and propagation in space and time is obtained through the finite-difference method. With this, a combination of basis set and grid methods is put forward for tackling multiregion time-dependent problems. In both regions, a high-order explicit scheme is employed for the time propagation. While, in a purely hydrogenic system no approximation is involved due to this separation, in multielectron systems the validity and the usefulness of the present method relies on the basic assumption of R-matrix theory, namely, that beyond a certain distance (encompassing region I) a single ejected electron is distinguishable from the other electrons of the multielectron system and evolves there (region II) effectively as a one-electron system. The method is developed in detail for single active electron systems and applied to the exemplar case of the hydrogen atom in an intense laser field.

Involvement of MAPKs in endostatin-mediated regulation of blood-retinal barrier function

Purpose: This study aimed to evaluate the effects of endostatin on tight junction (TJ) integrity in retinal microvascular endothelial cells (RMECs) in vitro and in vivo. Moreover, it was hypothesized that endostatin-induced occludin upregulation regulated VEGF(165)-mediated increases in endothelial cell permeability and involved activation of the MAPK signaling cascade. Endostatin is a 20-kDa fragment of collagen XVIII that has been shown to be efficacious in the eye by preventing retinal neovascularization. Endostatin is a specific inhibitor of endothelial cell proliferation, migration, and angiogenesis and has been reported to reverse VEGF-mediated increases in vasopermeability and to promote integrity of the blood-retinal barrier (BRB). In order to determine the mechanism of endostatin action on BRB integrity, we have examined the effects of endostatin on a number of intracellular pathways implicated in endothelial cell physiology. Methods: C57/Bl6 mice were injected with VEGF(165) and/or endostatin, and the distribution of occludin staining was determined using retinal flatmounts. Western blot analysis of RMECs treated with VEGF(165) and/or endostatin was used to determine changes in occludin expression and p38 MAPK and extracellular regulated kinase (ERK1/ERK2 MAPK) activation, while FD-4 flux across the RMEC monolayer was used to determine changes in paracellular permeability. Results: Endostatin prevented the discontinuous pattern of occludin staining observed at the retinal blood vessels of mice administered an intraocular injection of VEGF(165). It was shown that endostatin activated p38 MAPK 5 min after addition to RMECs and continued to do so for approximately 30 min. Endostatin was also shown to activate ERK1/ERK2 5 min after addition and continued to do so, albeit with less potency, up to and including 15 min after addition. Inhibition of p38 MAPK and ERK1/ERK2 prevented endostatin's ability to upregulate levels of occludin expression. Inhibition of these key signaling molecules was shown to prevent endostatin's ability to protect against VEGF(165)- mediated increases in paracellular permeability in vitro. However, it appears that p38 MAPK may play a more important role in VEGF-mediated permeability, as inhibition of ERK1/ERK2 will not prevent VEGF(165)- mediated permeability compared with control ( untreated) cells or cells treated with both a p38 MAPK inhibitor and VEGF(165). Conclusions: Occludin is important for the maintenance of tight junction integrity in vivo. In a p38 MAPK and ERK1/ERK2 dependent manner, endostatin was shown to upregulate the levels of expression of the tight junction protein occludin. Inhibition of these key MAPK components may prevent endostatin's ability to decrease VEGF(165)-induced paracellular permeability.

Flow-mediated dilatation of the brachial artery is a poorly reproducible indicator of microvascular function in Type I diabetes mellitus

Aim: Two Type I diabetes and control group comparator studies were conducted to assess the reproducibility of FMD and to analyse blood flow data normally discarded during FMD measurement.

Design: The studies were sequential and differed only with regard to operator and ultrasound machine. Seventy-two subjects with diabetes and 71 controls were studied in total.

Methods: Subjects had FMD measured conventionally. Blood velocity waveforms were averaged over 10 pulses post forearm ischaemia and their component frequencies analysed using the wavelet transform, a mathematical tool for waveform analysis. The component frequencies were grouped into 11 bands to facilitate analysis.

Results: Subjects were well-matched between studies. In Study 1, FMD was significantly impaired in subjects with Type I diabetes vs. controls (median 4.35%, interquartile range 3.10-4.80 vs. 6.50, 4.79-9.42, P < 0.001). No differences were detected between groups in Study 2, however. However, analysis of blood velocity waveforms yielded significant differences between groups in two frequency bands in each study.

Conclusions: This report highlights concerns over the reproducibility of FMD measures. Further work is required to fully elucidate the role of analysing velocity waveforms after forearm ischaemia.

GPVI levels in platelets: relationship to platelet function at high shear

We have investigated the density of the collagen receptors glycoprotein VI (GPVI) and alpha(2)beta(1) on human platelets and their relationship to polymorphisms within the GPVI gene. GPVI levels varied 1.5-fold and showed a weak correlation (r = 0.35) with the levels of alpha(2)beta(1), which varied 3-fold. GPVI genotype had a significant effect on receptor levels with carriers of the proline 219 allele (approximately 22% of the population) having 10% lower GPVI levels than the more common serine homozygotes. GPVI and alpha(2)beta(1) levels were found to be significantly decreased on platelets from patients with myeloproliferative disorders (MPDs). In both the MPD and the control group, GPVI levels were found not to affect platelet function under high shear in whole blood. Similarly murine platelets that express up to 5-fold lower levels of GPVI showed no significant difference than controls in thrombus formation on a high-density collagen-coated surface. However platelets lacking the GPVI/Fc receptor gamma-chain (FcR gamma-chain) complex or a functional FcR gamma-chain (immunoreceptor tyrosine-based activation motif [ITAM] point mutant) exhibited severely abrogated thrombus formation at 800 s(-1) and 1500 s(-1). These results demonstrate that GPVI levels are tightly controlled and play a critical role in thrombus formation on collagen; nevertheless, a range of receptor densities can support platelet function under high shear. (C) 2003 by The American Society of Hematology.