Effects of oral vitamin C on monocyte:Endothelial cell adhesion in healthy subjects

Monocyte recruitment and retention in the vasculature is influenced by oxidative stress and is involved in cardiovascular disease (CVD). Individuals with low plasma ascorbate are at elevated risk of CVD. It is unknown whether vitamin C supplementation affects monocyte adhesion to endothelial cells (ECs) in healthy non-smokers. In a randomised double-blind crossover study the effect of vitamin C supplementation (six weeks, 250 mg/day) was determined in subjects with normal (HIC) and below average (LOC) plasma vitamin C concentration at baseline (mean = 67μM, n = 20, mean = 32μM, n = 20, respectively). LOC subjects showed 30% greater monocyte adhesion to ECs. This was significantly reduced by 37% (P < 0.02) following vitamin C supplementation to levels of HIC monocyte adhesion. No differences in plasma malondialdehyde concentrations were observed between groups or after supplementation. In conclusion, vitamin C supplementation normalises monocyte adhesion in subjects with low plasma vitamin C (LOC). This process may be related to a direct effect on monocytes, independent of lipid peroxidation. © 2002 Elsevier Science (USA). All rights reserved.

α-Tocopherol supplementation does not affect monocyte endothelial adhesion or C-reactive protein levels but reduces soluble vascular adhesion molecule-1 in the plasma of healthy subjects

Vascular monocyte retention in the subintima is pivotal to the development of cardiovascular disease and is facilitated by up-regulation of adhesion molecules on monocytes/endothelial cells during oxidative stress. Epidemiological studies have shown that cardiovascular disease risk is inversely proportional to plasma levels of the dietary micronutrients, vitamin C and vitamin E (α-tocopherol). We have tested the hypothesis that α-tocopherol supplementation may alter endothelial/monocyte function and interaction in subjects with normal ascorbate levels (> 50 μM), as ascorbate has been shown to regenerate tocopherol from its oxidised tocopheroxyl radical form in vitro. Healthy male subjects received α-tocopherol supplements (400 IU RRR-α-tocopherol /day for 6 weeks) in a placebo-controlled, double-blind intervention study. There were no significant differences in monocyte CD11b expression, monocyte adhesion to endothelial cells, plasma C-reactive protein or sICAM- 1 concentrations post-supplementation. There was no evidence for nuclear translocation of NF-κB in isolated resting monocytes, nor any effect of α-tocopherol supplementation. However, post-supplementation, sVCAM-1 levels were decreased in all subjects and sE-selectin levels were increased in the vitamin C-replete group only; a weak positive correlation was observed between sE-selectin and α-tocopherol concentration. In conclusion, α-tocopherol supplementation had little effect on cardiovascular disease risk factors in healthy subjects and the effects of tocopherol were not consistently affected by plasma vitamin C concentration. © W. S. Maney & Son Ltd.

Direct modulatory effect of C-reactive protein on primary human monocyte adhesion to human endothelial cells

C-reactive protein (CRP) is the prototypic acute phase serum protein in humans. The effects of CRP on primary human monocyte adhesion molecule expression and interaction with the endothelium have not been studied. Herein, we describe an investigation into the phenotypic and functional consequences of CRP binding to peripheral blood monocytes ex vivo. Peripheral whole blood was collected from healthy, non-smoking males. Mononuclear cells (MNC) and monocytes were isolated by differential centrifugation using lymphoprep and Dynal negative isolation kit, respectively. Cells were exposed to CRP from 0 to 250 μg/ml for 0-60 min at 37°C and analysed for (a) CD11b, PECAM-1 (CD31) and CD32 expression by flow cytometry and (b) adhesion to LPS (1 μg/ml; 0-24 h) treated human umbilical vein endothelial cells (HUVEC). CD14+ monocyte expression of CD11b increased significantly up to twofold when exposed to CRP, compared to controls. There was no significant difference in CD32 expression, whereas CD31 expression decreased after exposure to CRP. CRP treatment of monocytes inhibited their adhesion to early LPS-activated HUVEC (0-5 h). However, the adhesion of CRP-treated monocytes to HUVEC was significantly greater to late activation antigens on HUVEC (24 h, LPS) compared to controls. We have shown that CRP can affect monocyte activation ex vivo and induce phenotypic changes that result in an altered recruitment to endothelial cells. This study provides the first evidence for a further role for C-reactive protein in both monocyte activation and adhesion, which may be of importance during an inflammatory event.

RGD-independent cell adhesion via a tissue transglutaminase-fibronectin matrix promotes fibronectin fibril deposition and requires syndecan-4/2 and α5β1 integrin co-signaling

Fibronectin (FN) deposition mediated by fibroblasts is an important process in matrix remodeling and wound healing. By monitoring the deposition of soluble biotinylated FN, we show that the stress-induced TG-FN matrix, a matrix complex of tissue transglutaminase (TG2) with its high affinity binding partner FN, can increase both exogenous and cellular FN deposition and also restore it when cell adhesion is interrupted via the presence of RGD-containing peptides. This mechanism does not require the transamidase activity of TG2 but is activated through an RGD-independent adhesion process requiring a heterocomplex of TG2 and FN and is mediated by a syndecan-4 and ß1 integrin co-signaling pathway. By using a5 null cells, ß1 integrin functional blocking antibody, and a a5ß1 integrin targeting peptide A5-1, we demonstrate that the a5 and ß1 integrins are essential for TG-FN to compensate RGD-induced loss of cell adhesion and FN deposition. The importance of syndecan-2 in this process was shown using targeting siRNAs, which abolished the compensation effect of TG-FN on the RGD-induced loss of cell adhesion, resulting in disruption of actin skeleton formation and FN deposition. Unlike syndecan-4, syndecan-2 does not interact directly with TG2 but acts as a downstream effector in regulating actin cytoskeleton organization through the ROCK pathway. We demonstrate that PKCa is likely to be the important link between syndecan-4 and syndecan-2 signaling and that TG2 is the functional component of the TG-FN heterocomplex in mediating cell adhesion via its direct interaction with heparan sulfate chains.

Articular cartilage glycosaminoglycans inhibit the adhesion of endothelial cells

Articular cartilage undergoes severe loss of proteoglycan and its constituent glycosaminoglycans (GAGs) in osteoarthritis. We hypothesize that the low GAG content of osteoarthritic cartilage renders the tissue susceptible to pathological vascularization. This was investigated using an in vitro angiogenesis model assessing endothelial cell adhesion to GAG-depleted cartilage explants. Bovine cartilage explants were treated with hyaluronidase to deplete GAG content and then seeded with fluorescently tagged human endothelial cells (HMEC-1). HMEC-1 adherence was assessed after 4 hr and 7 days. The effect of hyaluronidase treatment on GAG content, chondrocyte viability, and biochemical composition of the extracellular matrix was also determined. Hyaluronidase treatment reduced the GAG content of cartilage explants by 78 ± 3% compared with that of controls (p <0.0001). GAG depletion was associated with significantly more HMEC-1 adherence on both the surface (superficial zone) and the underside (deep zone) of the explants (both p <0.0001). The latter provided a more favorable environment for extended culture of HMEC-1 compared with the articulating surface. Hyaluronidase treatment altered the immunostaining for chondroitin sulfate epitopes, but not for lubricin. Our results support the hypothesis that articular cartilage GAGs are antiadhesive to endothelial cells and suggest that chondroitin sulfate and/or hyaluronan are responsible. The loss of these GAGs in osteoarthritis may allow osteochondral angiogenesis resulting in disease progression.

Psychological contract breach in a Chinese context:an integrative approach

This study examined the antecedents and outcomes of psychological contract breach as well as why and how psychological contract breach is related to these outcomes. Respondents were Hong Kong Chinese employees (N=152). Results showed organizational change and history of contract breach to be related to psychological contract breach which, in turn, was related to turnover intentions, psychological withdrawal behaviour, and civic virtue. Further, trust in employer fully mediated the relationship between psychological contract breach and the work outcomes of psychological withdrawal behaviour and civic virtue but partially mediated the psychological contract breach–turnover intentions relationship. Lastly, interactional justice failed to moderate the relationship between psychological contract breach and the work outcomes.

S100P dissociates myosin IIA filaments and focal adhesion sites to reduce cell adhesion and enhance cell migration

S100 proteins promote cancer cell migration and metastasis. To investigate their roles in the process of migration we have constructed inducible systems for S100P in rat mammary and human HeLa cells that show a linear relationship between its intracellular levels and cell migration. S100P, like S100A4, differentially interacts with the isoforms of nonmuscle myosin II (NMIIA, K(d) = 0.5 µm; IIB, K(d) = 8 µm; IIC, K(d) = 1.0 µm). Accordingly, S100P dissociates NMIIA and IIC filaments but not IIB in vitro. NMIIA knockdown increases migration in non-induced cells and there is no further increase upon induction of S100P, whereas NMIIB knockdown reduces cell migration whether or not S100P is induced. NMIIC knockdown does not affect S100P-enhanced cell migration. Further study shows that NMIIA physically interacts with S100P in living cells. In the cytoplasm, S100P occurs in discrete nodules along NMIIA-containing filaments. Induction of S100P causes more peripheral distribution of NMIIA filaments. This change is paralleled by a significant drop in vinculin-containing, actin-terminating focal adhesion sites (FAS) per cell. The induction of S100P, consequently, causes significant reduction in cellular adhesion. Addition of a focal adhesion kinase (FAK) inhibitor reduces disassembly of FAS and thereby suppresses S100P-enhanced cell migration. In conclusion, this work has demonstrated a mechanism whereby the S100P-induced dissociation of NMIIA filaments leads to a weakening of FAS, reduced cell adhesion, and enhanced cell migration, the first major step in the metastatic cascade.

Casebook on contract law

Jill Poole's best-selling Casebook on Contract Law provides a clear and well-structured explanation of the principles and rules of contract law through a comprehensive selection of case law, addressing all aspects encountered on undergraduate courses. The coverage in this new edition has been revised to incorporate all recent significant decisions and judgments made by the House of Lords and the Court of Appeal. Extracts have been chosen from a wide range of historical and contemporary cases to illustrate the reasoning processes of the court and how legal principles are developed, thus enabling cases to be analysed and discussed independently while, taken as a whole, the chapters provide a sound understanding of the modern law of contract. Succinct author commentary focuses the reader on the key elements within the extracts, while thought-provoking questions are posed throughout to develop a more in-depth appreciation of the subject. Online resource centre Student resources - Updates - Guidance on answering questions - Guidance on reading cases - Questions and answers.

Textbook on contract law

This ninth edition of the established Textbook on Contract Law by Jill Poole provides a wide-ranging and straightforward exposition of contract law. The text opens with an overview of the main issues surrounding contract law which places the subject in its wider context, then goes on to give a clear explanation of all the major areas of contract law encountered on undergraduate courses. Features of the book includes chapter summaries to draw key themes and issues together; examples and questions to encourage a deeper understanding of the often complex points of law; and extensive further reading lists of both texts and articles to guide students towards the most relevant and up-to-date resources available. Online resource centre Lecturer resources - Testbank of 150 multiple-choice questions Student resources - Guidance on answering questions in contract law - Questions and answers - Student questions - Updates - Web links

Damages for breach of contract

This practical book deals solely with those damages arising as a breach of contract, where the aim of the damages is to place the plaintiff in the same position as if the contract had been performed. The book is split into three main parts: general principles such as limitations, causation, remoteness, mitigation and contributory negligence; specific breaches, such as sale of goods, supply of services, travel contracts and sale of land; and general issues and procedures. The only authoritative practitioner work focusing on this area, it provides a high-level, comprehensive and practical text.

Casebook on contract law

This volume provides students with a comprehensive selection of the cases most likely to be encountered on contract law courses and is specifically designed to meet their needs. The case law is helpfully structured and presented under clear headings, with the emphasis on explaining the decisions and their implications in order to promote better understanding. The fifth edition incorporates important judgments and assesses the significance of recent decisions of the House of Lords such as Attorney-General v Blake and Alfred McAlpine Construction Ltd v Panatown Ltd and the decisions of the Court of Appeal in Director General of Fair Trading v First National Bank plc and Barclays Bank v Coleman. Important recent decisions on remedies for misrepresentation have also been included.

Casebook on contract law

The law of contract can be a complex and technical subject, rvt the new edition of Jill Poole's Casebook on Contract provides a clear and well-structured exposition of the principles and rules through a comprehensive selection of case law, addressing all aspects encountered on undergraduate courses. Opening with a chapter of valuable advice and guidance on how to successfully develop and improve the essential skills of case-reading, featuring two worked examples, the coverage in this sixth edition expands to incorporate all recent significant decisions and judgments made by the House of Lords and Court of Appeal such as, Director General of Fair Trading v First National Bank plc, Farley v Skinner, Royal Bank of Scotland v Etridge and UCB Corporate Services v Williams. Interesting recent decisions in relation to battle of forms, terms, exemption clauses and misrepresentation are also included. Extracts have been chosen from a wide range of historical and contemporary cases to illustrate the reasoning processes of the court, why decisions are made and how legal principles are developed - enabling cases to be analysed and discussed independently while, taken as a whole, the chapters provide a sound understanding of the modern law of contract. The section on damages for breach of contract has been expanded to reassess Ruxley Electronics and Construction Ltd v Forsyth in the light of Farley v Skinner, the future of Addis v Gramophone Co Ltd is considered in the light of Johnson v Unisys Ltd and Attorney General v Blake is examined in the light of the decision in Esso Petroleum Co Ltd v Niad Ltd. Succinct author comment focuses the reader on the key elements within the extracts, while thought-provoking questions are posed throughout to develop more in-depth analysis. The logical and clear organization of topics has been further improved to more accurately echo the order adopted within the author's popular textbook and closer crossreferencing to this text has been incorporated to highlight where more detailed discussion of issues arising from the caselaw can be explored. As a result, this new edition can be used both as a traditional casebook and as a companion volume to Poole's Textbook on Contract. This edition is also supported by a new companion web site that offers the benefits of essential updating of key materials, sample questions, lists for key further reading sources and relevant web links, additional relevant cases and materials and guidance on successful exam technique. As with previous editions, Casebook on Contract is an invaluable primary source and an essential study aid for all those following elements of contract law as part of the LLB and CPE, as well as for students from related disciplines such as Accounting and Business.

Casebook on contract law

Jill Poole's best-selling "Casebook on Contract Law" provides a clear and well-structured exposition of the principles and rules through a comprehensive selection of case law, addressing all aspects encountered on undergraduate courses. Extracts have been chosen from a wide range of historical and contemporary cases to illustrate the reasoning processes of the court, why decisions are made and how legal principles are developed - enabling cases to be analyzed and discussed independently while, taken as a whole, the chapters provide a sound understanding of the modern law of contract. Succinct author commentary focuses the reader on the key elements within the extracts, while thought-provoking questions are posed throughout to develop more in-depth analysis. This book is accompanied by a specifically designed companion web site which provides: Questions in contract law; Guidance on answering questions; Guidance on reading cases; Questions and answers; and Updates.