John L. Harwood

Bio: John L. Harwood is an academic researcher from Cardiff University. The author has contributed to research in topics: Lipid metabolism & Fatty acid. The author has an hindex of 60, co-authored 420 publications receiving 16081 citations. Previous affiliations of John L. Harwood include John L. Scott & Spanish National Research Council.

Modification of palm oil for anti-inflammatory nutraceutical properties.

Abstract: Palm oil is one of the most important edible oils in the world. Its composition (rich in palmitate and oleate) make it suitable for general food uses but its utility could be increased if its fatty acid quality could be varied. In this study, we have modified a palm olein fraction by transesterification with the n-3 polyunsaturated fatty acids, α-linolenate or eicosapentaenoic acid (EPA). Evaluation of the potential nutritional efficacy of the oils was made using chondrocyte culture systems which can be used to mimic many of the degenerative and inflammatory pathways involved in arthritis. On stimulation of such cultures with interleukin-1α, they showed increased expression of cyclooxygenase-2, the inflammatory cytokines tumour necrosis factor-α (TNF-α), IL-1α and IL-1β and the proteinase ADAMTS-4. This increased expression was not affected by challenge of the cultures with palm olein alone but showed concentration-dependent reduction by the modified oil in a manner similar to EPA. These results show clearly that it is possible to modify palm oil conveniently to produce a nutraceutical with effective anti-inflammatory properties.

Interferon-gamma increases macrophage phospholipid polyunsaturation: a possible mechanism of endotoxin sensitivity.

Abstract: Incubation of murine macrophages or the macrophage-like cell line P388D with interferon-gamma in vitro induced a significant increase in the polyunsaturated fatty acid content of phosphatidylethanolamine. These increases were time and dose-dependent, being maximal at 12 hours and with 5000 U/ml interferon and were inhibited in the presence of anti-interferon-gamma monoclonal antibody. Interferon-gamma induced a significant increase in linoleate in peritoneal macrophages while in the cell line arachidonate was significantly increased. These results are of interest because such increases in the polyunsaturated fatty acid content of phosphatidylethanolamine were previously shown by us to be associated with increased sensitivity to endotoxin in mice in vivo. The implications for interferon-gamma sensitizing to endotoxin are discussed.

Interferon-γ: an overview of signals, mechanisms and functions

Abstract: Interferon-gamma (IFN-gamma) coordinates a diverse array of cellular programs through transcriptional regulation of immunologically relevant genes. This article reviews the current understanding of IFN-gamma ligand, receptor, signal transduction, and cellular effects with a focus on macrophage responses and to a lesser extent, responses from other cell types that influence macrophage function during infection. The current model for IFN-gamma signal transduction is discussed, as well as signal regulation and factors conferring signal specificity. Cellular effects of IFN-gamma are described, including up-regulation of pathogen recognition, antigen processing and presentation, the antiviral state, inhibition of cellular proliferation and effects on apoptosis, activation of microbicidal effector functions, immunomodulation, and leukocyte trafficking. In addition, integration of signaling and response with other cytokines and pathogen-associated molecular patterns, such as tumor necrosis factor-alpha, interleukin-4, type I IFNs, and lipopolysaccharide are discussed.

Microalgal triacylglycerols as feedstocks for biofuel production: perspectives and advances

Abstract: Microalgae represent an exceptionally diverse but highly specialized group of micro-organisms adapted to various ecological habitats. Many microalgae have the ability to produce substantial amounts (e.g. 20-50% dry cell weight) of triacylglycerols (TAG) as a storage lipid under photo-oxidative stress or other adverse environmental conditions. Fatty acids, the building blocks for TAGs and all other cellular lipids, are synthesized in the chloroplast using a single set of enzymes, of which acetyl CoA carboxylase (ACCase) is key in regulating fatty acid synthesis rates. However, the expression of genes involved in fatty acid synthesis is poorly understood in microalgae. Synthesis and sequestration of TAG into cytosolic lipid bodies appear to be a protective mechanism by which algal cells cope with stress conditions, but little is known about regulation of TAG formation at the molecular and cellular level. While the concept of using microalgae as an alternative and renewable source of lipid-rich biomass feedstock for biofuels has been explored over the past few decades, a scalable, commercially viable system has yet to emerge. Today, the production of algal oil is primarily confined to high-value specialty oils with nutritional value, rather than commodity oils for biofuel. This review provides a brief summary of the current knowledge on oleaginous algae and their fatty acid and TAG biosynthesis, algal model systems and genomic approaches to a better understanding of TAG production, and a historical perspective and path forward for microalgae-based biofuel research and commercialization.