Dietary supplementation with vitamin C but not vitamin E reduces constitutive expression of ICAM-1 in peripheral blood monocytes of normal subjects with low plasma vitamin C levels

Monocytes play a central role in inflammatory responses through systemic antigen presentation and cytokine secretion. Regulation of monocyte adhesion molecule and inflammatory gene expression is via redox sensitive transcription factors. Therefore we have investigated the hypothesis that dietary antioxidant supplementation with vitamins C (250mg/d) or E (400iU/d) for six weeks can modulate monocyte ICAM-1 expression in healthy male subjects with low plasma vitamin C at baseline. In a randomised, double-blind, crossover study, ICAM-1 mRNA and protein was analysed using quantitative RTPCR with ELISA measurement of PCR products and by flow cytometry and ELISA respectively. Monocyte numbers were unaltered by supplementation. Subjects with low plasma vitamin C (<50uM) prior to supplementation expressed higher levels of monocyte ICAM-1 mRNA, and showed a significant (50%) reduction in ICAM-1 mRNA expression after 6 weeks of 250mg/d vitamin C supplementation compared to subjects with normal plasma vitamin C. This was paralleled by a reduction in plasma sICAM-1. Vitamin E supplementation had no effect on ICAM-1 expression. For the first time, these results show that dietary vitamin C can modulate monocyte ICAM-1 gene expression in vivo, where regulation of gene expression represents a novel mechanism for benefit from dietary antioxidants.

Reduction in blood glutathione levels occurs similarly in patients with primary-open angle or normal tension glaucoma

PURPOSE. To investigate in parallel the systemic glutathione levels of patients suffering from primary open angle glaucoma (POAG) or normal tension glaucoma (NTG) with comparable functional loss. METHODS. Thirty-four POAG patients, 30 NTG patients, and 53 controls were subjected to blood analysis to detect the level of circulating glutathione in its reduced (GSH) and oxidized (GSSG) forms. Systemic blood pressure (BP) and ocular perfusion pressure (OPP) parameters were also determined. RESULTS. Independent of age, POAG and NTG patients demonstrated significantly lower GSH and t-GSH levels than age-matched controls (P < 0.001). Additionally, a lower redox index was found, but in POAG patients only, in comparison to both NTG and control groups (P = 0.020). GSSG levels were, however, similar between all study groups (P > 0.05). CONCLUSIONS. This study demonstrates, for the first time, that both POAG and NTG patients exhibit lower GSH and t-GSH levels than age-matched controls, indicating a similar general compromise of the antioxidant defense systems may exist in both conditions. © 2013 The Association for Research in Vision and Ophthalmology, Inc.

Ocular and systemic markers for vascular function in those at risk of type 2 diabetes mellitus and cardiovascular disease

The devastating impact of Type 2 Diabetes Mellitus (T2DM) -related morbidity and mortality on global healthcare is escalating with higher prevalences of obesity, poor diet, and sedentary lifestyles. Therefore, the clinical need for early diagnosis and prevention in groups of high-risk individuals is necessary. The purpose of this thesis was to investigate the use of surrogate markers, namely retinal vascular function, to determine future vascular endothelial dysfunction, atherosclerosis, large vessel disease and cardiovascular risk in certain groups. This namely covered normoglycaemic and normotensive South Asians (SAs), those with Impaired-Glucose Tolerance (IGT) and individuals with a familial history (FH) of T2DM. Additionally the effect of overweight and obesity was studied. The techniques and modified protocols adopted for this thesis involved the investigation of endothelial function by means of vascular reactivity at the ocular and systemic level. Furthermore, the relationships between retinal and systemic function with circulating markers for endothelial cell function and cardiovascular risk markers were explored. The principal studies and findings of the research were: Vascular Function in Normoglycaemic Individuals with and without a FH of T2DM WE FH individuals exhibited higher levels of total cholesterol levels that correlated well with the retinal arterial dilation amplitude to flicker light stimulus. However this did not extend to noticeable differences in markers for endothelial cell damage and impaired retinal and systemic function. Vascular Function in Normoglycaemic South-Asians vs. White-Europeans without a FH and Vascular Disturbances Compared to healthy WEs (normo -glycaemic and -tensive), SA participants exhibited levels of dyslipidaemia and a state of oxidative stress that extended to impaired vascular function as detected by reduced brachial artery flow-mediated dilation, slower retinal arterial vessel dilation reaction times (Appendix 3) and steeper constriction profiles. Furthermore, gender sub-group analysis presented in a sub-chapter shows that SA males demonstrated 24-hour systemic blood pressure (BP) and heart rate variability (HRV) abnormalities and heightened cardiovascular disease (CVD) risk. Vascular Function in Individuals Newly Diagnosed with IGT as compared to Normoglycaemic Healthy Controls Newly-diagnosed WE and SA IGT patients showed a greater risk for CVD and T2DM progression by means of 24-hour BP abnormalities, dyslipidaemia, increased carotid artery intimal-media thickness (c-IMT), Framingham scores and cholesterol ratios. Additionally, pre-clinical markers for oxidative stress and endothelial dysfunction, as evident by significantly lower levels of plasma glutathione and increased levels of von-Willebrand factor in IGT individuals, extended to impaired vascular systemic and retinal function compared to normal controls. This originally shows retinal, systemic and biochemical disturbances in newly-diagnosed IGT not previously reported before. Vascular Function in Normal, Overweight and Obese Individuals of SA and WE Ethnicity In addition to the intended study chapters, the thesis also investigated the influence of obesity and overweight on vascular function. Most importantly, it was found for the first time that compared to lean individuals it was overweight and not obese individuals that exhibited signs of vascular systemic and ocular dysfunction that was evident alongside markers of atherosclerosis, CVD risk and endothelial damage.

Combined bioreaction and separation in centrifugal fields

The aim of this work has been to investigate the principle of combined centrifugal bioreaction-separation. The production of dextran and fructose by the action of the enzyme dextransucrase on sucrose was employed to elucidate some of the principles of this type of process. Dextran is a valuable pharmaceutical product used mainly as a blood volume expander and blood flow improver whilst fructose is an important dietary product. The development of a single step process capable of the simultaneous biosynthesis of dextran and the separation of the fructose by-product should improve dextran yields whilst reducing capital and processing costs. This thesis shows for the first time that it is possible to conduct successful bioreaction-separations using a rate-zonal centrifugation technique. By layering thin zones of dextrasucrase enzyme onto sucrose gradients and centrifuging, very high molecular weight (MW) dextran-enzyme complexes were formed that rapidly sedimented through the sucrose substrate gradients under the influence of the applied centrifugal field. The low MW fructose by-product sedimented at reduced rates and was thus separated from the enzyme and dextran during the reaction. The MW distribution of dextran recovered from the centrifugal bioreactor was compared with that from a conventional batch bioreactor. The results indicated that the centrifugal bioreactor produced up to 100% more clinical dextran with MWs of between 12 000 and 98 000 at 20% w/w sucrose concentrations than conventional bioreactors. This was due to the removal of acceptor fructose molecules from the sedimenting reaction zone by the action of the centrifugal field. Higher proportions of unwanted lower MW dextran were found in the conventional bioreactor than in the centrifugal bioreactor-separator. The process was studied on a number of alternative centrifugal systems. A zonal rotor fitted with a reorienting gradient core proved most successful for the evaluation of bioreactor performance. Results indicated that viscosity build-up in the reactor must be minimised in order to increase the yields of dextran per unit time and improve product separation. A preliminary attempt at modelling the process has also been made.

Time-resolved Q-factor measurement and its application in performance analysis of 42.6 Gbit/s packets generated by SGDBR lasers

We demonstrate a novel time-resolved Q-factor measurement technique and demonstrate its application in the analysis of optical packet switching systems with high information spectral density. For the first time, we report the time-resolved Q-factor measurement of 42.6 Gbit/s AM-PSK and DQPSK modulated packets, which were generated by a SGDBR laser under wavelength switching. The time dependent degradation of Q-factor performance during the switching transient was analyzed and was found to be correlated with different laser switching characteristics in each case.

First demonstration of 2μm data transmission in a low-loss hollow core photonic Bandgap fiber

The first demonstration of a hollow core photonic bandgap fiber suitable for high-rate data transmission at 2µm is presented. Using a custom built Thulium doped fiber amplifier, error-free 8Gbit/s transmission in an optically amplified data channel at 2008nm is reported for the first time.

The role of apoptotic cell clearance in a high-lipid environment:links to ageing

Individuals within the aged population show an increased susceptibility to infection, implying a decline in immune function, a phenomenon known as immunosenescence. Paradoxically, an increase in autoimmune disease, such as rheumatoid arthritis, is also associated with ageing, therefore some aspects of the immune system appear to be inappropriately active in the elderly. The above evidence suggests inappropriate control of the immune system as we age. Macrophages, and their precursors monocytes, play a key role in control of the immune system. They play an important role in host defence in the form of phagocytosis, and also link the innate and adaptive immune system via antigen presentation. Macrophages also have a reparative role, as professional phagocytes of dead and dying cells. Clearance of apoptotic cells by macrophages has also been shown to directly influence immune responses in an anti-inflammatory manner. Inappropriate control of macrophage function with regards to dead cell clearance may contribute to pathology as we age. The aims of this study were to assess the impact of lipid treatment, as a model of the aged environment, on the ability of macrophages to interact with, and respond to, apoptotic cells. Using a series of in vitro cell models, responses of macrophages (normal and lipid-loaded) to apoptotic macrophages (normal and lipid-loaded) were investigated. Monocyte recruitment to apoptotic cells, a key process in resolving inflammation, was assessed in addition to cytokine responses. Data here shows, for the first time, that apoptotic macrophages (normal and lipid-loaded) induce inflammation in human monocyte-derived macrophages, a response that could drive inflammation in age-associated pathology e.g. atherosclerosis. Monoclonal antibody inhibition studies suggest the classical chemokine CX3CL1 may be involved in monocyte recruitment to apoptotic macrophages, but not apoptotic foam cells, therefore differential clearance strategies may be employed following lipid-loading. CD14, an important apoptotic cell tethering receptor, was not found to have a prominent role in this process, whilst the role for ICAM-3 remains unclear. Additionally, a small pilot study using macrophages from young (<25) and mid-life (>40) donors was undertaken. Preliminary data was gathered to assess the ability of primary human monocyte-derived macrophages, from young and mid-life donors, to interact with, and respond to, apoptotic cells. MØ from mid-life individuals showed no significant differences in their ability to respond to immune modulation by apoptotic cells compared to MØ from young donors. Larger cohorts would be required to investigate whether immune modulation of MØ by apoptotic cells contribute to inflammatory pathology throughout ageing.

Cell exclusion in couette flow:evaluation through flow visualisation and mechanical forces

Cell exclusion is the phenomenon whereby the hematocrit and viscosity of blood decrease in areas of high stress. While this is well known in naturally occurring Poiseuille flow in the human body, it has never previously been shown in Couette flow, which occurs in implantable devices including blood pumps. The high-shear stresses that occur in the gap between the boundaries in Couette flow are known to cause hemolysis in erythrocytes. We propose to mitigate this damage by initiating cell exclusion through the use of a spiral-groove bearing (SGB) that will provide escape routes by which the cells may separate themselves from the plasma and the high stresses in the gap. The force between two bearings (one being the SGB) in Couette flow was measured. Stained erythrocytes, along with silver spheres of similar diameter to erythrocytes, were visualized across a transparent SGB at various gap heights. A reduction in the force across the bearing for human blood, compared with fluids of comparable viscosity, was found. This indicates a reduction in the viscosity of the fluid across the bearing due to a lowered hematocrit because of cell exclusion. The corresponding images clearly show both cells and spheres being excluded from the gap by entering the grooves. This is the first time the phenomenon of cell exclusion has been shown in Couette flow. It not only furthers our understanding of how blood responds to different flows but could also lead to improvements in the future design of medical devices.

Long-range and high-resolution correlation optical time-domain reflectometry utilizing an all optical chaotic source

A high resolution optical time domain reflectometry (OTDR) based on an all-fiber chaotic source is demonstrated. We analyze the key factors limiting the operational range of such an OTDR, e.g., integral Rayleigh backscattering and the fiber loss, which degrade the optical signal to noise ratio at the receiver side, and then the guideline for counter-act such signal fading is discussed. The experimentally demonstrated correlation OTDR presents ability of 100km sensing range and 8.2cm spatial resolution (1.2 million resolved points), as a verification of the theoretical analysis. To the best of our knowledge, this is the first time that correlation OTDR measurement is performed over such a long distance with such high precision.

First experimental demonstration of nonlinear inverse synthesis transmission over transoceanic distances

We demonstrate for the first time, the transmission performance of 10Gbaud nonlinear inverse synthesis based signal over transoceanic distances, showing a significant improvement in data capacity x distance product (x12) compared with other NFT-based systems.