DSpace Collection: Clinical Medicine (Scholarly Publications)

Dietary fat, abdominal obesity and smoking modulate the relationship between plasma complement component 3 concentrations and metabolic syndrome risk

Sun, 01 Jan 2012 00:00:00 GMT

Title: Dietary fat, abdominal obesity and smoking modulate the relationship between plasma complement component 3 concentrations and metabolic syndrome risk Author: MC MANUS, ROSS Abstract: Objective: Chronic inflammation plays a role in the pathogenesis of metabolic syndrome (MetS) and cardiovascular disease (CVD). Complement component 3 (C3) is a novel cardiometabolic risk factor. Whether dietary fat intake modulates MetS risk conferred by elevated C3 concentrations is unknown. Our objective is to investigate the relationship between C3 concentrations and risk of the MetS and its phenotypes, and to further examine whether dietary fat intake modulates these relationships. Methods: Biochemical, dietary and lifestyle measurements were determined in the LIPGENE-SU.VI.MAX study of MetS cases and matched controls (n = 1754). Results: Elevated C3 concentrations (> median) were associated with increased risk of impaired insulin sensitivity [OR 1.78, CI 1.34-2.36, P < 0.0001], insulin resistance [OR 1.73, CI 1.31-2.89, P = 0.0001], abdominal obesity [OR 2.15, CI 1.43-3.24, P = 0.0002] and low HDL cholesterol [OR 1.40, CI 1.05-1.86, P = 0.02] compared to low C3 concentrations. Increased MetS risk conferred by elevated C3 concentrations [OR 3.11, 95% CI 2.52-3.82, P < 0.0001] was further accentuated among high dietary fat consumers [OR 4.80, 95% CI 2.77-8.33, P < 0.0001] (particularly of saturated [OR 4.05, 95% CI 2.33-7.05, P < 0.0001] and monounsaturated fat [OR 4.48, 95% CI 2.62-7.56, P < 0.0001]), and smokers [OR 3.83, 95% CI 2.12-6.94, P < 0.0001], however this effect was abolished in abdominally lean individuals [OR 1.46, 95% CI 0.69-3.14, P = 0.33]. Conclusions: Dietary fat (intake and composition), abdominal obesity and smoking modulate the relationship between elevated plasma C3 concentrations and MetS risk. Description: PUBLISHED

Enhancement of chemokine function as an immunomodulatory strategy employed by human herpesviruses.

Thu, 02 Feb 2012 00:00:00 GMT

Title: Enhancement of chemokine function as an immunomodulatory strategy employed by human herpesviruses. Author: FALLON, PADRAIC GERARD Abstract: Herpes simplex virus (HSV) types 1 and 2 are highly prevalent human neurotropic pathogens that cause a variety of diseases, including lethal encephalitis. The relationship between HSV and the host immune system is one of the main determinants of the infection outcome. Chemokines play relevant roles in antiviral response and immunopathology, but the modulation of chemokine function by HSV is not well understood. We have addressed the modulation of chemokine function mediated by HSV. By using surface plasmon resonance and crosslinking assays we show that secreted glycoprotein G (SgG) from both HSV-1 and HSV-2 binds chemokines with high affinity. Chemokine binding activity was also observed in the supernatant of HSV-2 infected cells and in the plasma membrane of cells infected with HSV-1 wild type but not with a gG deficient HSV-1 mutant. Cell-binding and competition experiments indicate that the interaction takes place through the glycosaminoglycan-binding domain of the chemokine. The functional relevance of the interaction was determined both in vitro, by performing transwell assays, time-lapse microscopy, and signal transduction experiments; and in vivo, using the air pouch model of inflammation. Interestingly, and in contrast to what has been observed for previously described viral chemokine binding proteins, HSV SgGs do not inhibit chemokine function. On the contrary, HSV SgGs enhance chemotaxis both in vitro and in vivo through increasing directionality, potency and receptor signaling. This is the first report, to our knowledge, of a viral chemokine binding protein from a human pathogen that increases chemokine function and points towards a previously undescribed strategy of immune modulation mediated by viruses. Description: PUBLISHED

Syphilis consequences and implications in delayed diagnosis: five cases of secondary syphilis presenting with ocular symptoms.

Fri, 01 Jan 2010 00:00:00 GMT

Title: Syphilis consequences and implications in delayed diagnosis: five cases of secondary syphilis presenting with ocular symptoms. Author: BERGIN, COLM Abstract: Ocular manifestations of syphilis are uncommon. Five cases of ocular syphilis are presented, in four of which there was a delay in diagnosis. Four of the patients were men who have sex with men (MSM), and four patients were HIV negative. Description: PUBLISHED

The chylomicron: relationship to atherosclerosis.

Sun, 01 Jan 2012 00:00:00 GMT

Title: The chylomicron: relationship to atherosclerosis. Author: TOMKIN, GERALD H Abstract: The B-containing lipoproteins are the transporters of cholesterol, and the evidence suggests that the apo B48-containing postprandial chylomicron particles and the triglyceride-rich very low density lipoprotein (VLDL) particles play an important part in the development of the plaque both directly and indirectly by their impact on LDL composition. The ratio of dietary to synthesised cholesterol is variable but tightly regulated: hence intervention with diet at best reduces serum cholesterol by <20% andusually <10%. Statins are the mainstay of cholesterol reduction therapy, but they increase cholesterol absorption, an example of the relationship between synthesis and absorption. Inhibition of cholesterol absorption with Ezetimibe, an inhibitor of Niemann Pick C1-like 1 (NPC1-L1), the major regulator of cholesterol absorption, increases cholesterol synthesis and hence the value of adding an inhibitor of cholesterol absorption to an inhibitor of cholesterol synthesis. Apo B48, the structural protein of the chylomicron particle, is synthesised in abundance so that the release of these particles is dependent on the amount of cholesterol and triglyceride available in the intestine. This paper will discuss cholesterol absorption and synthesis, chylomicron formation, and the effect of postprandial lipoproteins on factors involved in atherosclerosis. Description: PUBLISHED

New fluorescent bile acids: Synthesis, chemical characterization, and disastereoselective uptake by Caco-2 cells of 3-deoxy 3-NBD-amino deoxycholic and ursodeoxycholic acid

Sun, 01 Jan 2012 00:00:00 GMT

Title: New fluorescent bile acids: Synthesis, chemical characterization, and disastereoselective uptake by Caco-2 cells of 3-deoxy 3-NBD-amino deoxycholic and ursodeoxycholic acid Author: EHRHARDT, CARSTEN; LONG, AIDEEN; GILMER, JOHN FRANCIS; KEAVENY, RAYMOND DOMINIC; MAJER, FERENC; WANG, JUN Abstract: Deoxycholic acid (DCA), a secondary bile acid (BA), and ursodeoxycholic acid (UDCA), a tertiary BA, cause opposing effects in vivo and in cell suspensions. Fluorescent analogues of DCA and UDCA could help investigate important questions about their cellular interactions and distribution. We have prepared a set of isomeric 3α- and 3β-amino analogues of UDCA and DCA and derivatised these with the discrete fluorophore, 4-nitrobenzo-2-oxa-1,3-diazol (NBD), forming the corresponding four fluorescent adducts. These absorb in the range 465–470 nm and fluoresce at approx. 535 nm. In order to determine the ability of the new fluorescent bile acids to mimic the parents, their uptake was studied using monolayers of Caco-2 cells, which are known to express multiple proteins of the organic anion-transporting peptide (OATP) subfamily of transporters. Cellular uptake was monitored over time at 4°C and 37°C to distinguish between passive and active transport. All four BA analogues were taken up but in a strikingly stereo- and structure-specific manner, suggesting highly discriminatory interactions with transporter protein(s). The α-analogues of DCA and to a lesser extent UDCA were actively transported, whereas the β-analogues were not. The active transport process was saturable, with Michaelis-Menten constants for 3α-NBD DCA (5) being Km = 42.27±12.98 μM and Vmax = 2.8±0.4 nmol/(mg protein∗min) and for 3α-NBD UDCA (3) Km = 28.20±7.45 μM and Vmax = 1.8±0.2 nmol/(mg protein∗min). These fluorescent bile acids are promising agents for investigating questions of bile acid biology and for detection of bile acids and related organic anion transport processes. Description: PUBLISHED

Identification of the synthetic cannabinoid R(+)WIN55,212-2 as a novel regulator of IFN regulatory factor 3 (IRF3) activation and IFN-{beta} expression: relevance to therapeutic effects in models of multiple sclerosis.

Sat, 01 Jan 2011 00:00:00 GMT

Title: Identification of the synthetic cannabinoid R(+)WIN55,212-2 as a novel regulator of IFN regulatory factor 3 (IRF3) activation and IFN-{beta} expression: relevance to therapeutic effects in models of multiple sclerosis. Author: FALLON, PADRAIC GERARD Abstract: β-Interferons (IFN-βs) represent one of the first line treatments for relapsing-remitting multiple sclerosis, slowing disease progression while reducing the frequency of relapses. Despite this, more effective, well tolerated therapeutic strategies are needed. Cannabinoids palliate experimental autoimmune encephalomyelitis (EAE) symptoms and have therapeutic potential in MS patients although the precise molecular mechanism for these effects is not understood. Toll-like receptor (TLR) signaling controls innate immune responses and TLRs are implicated in MS. Here we demonstrate that the synthetic cannabinoid R(+)WIN55,212-2 is a novel regulator of TLR3 and TLR4 signaling by inhibiting the pro-inflammatory signaling axis triggered by TLR3 and TLR4, whereas selectively augmenting TLR3-induced activation of IFN regulatory factor 3 (IRF3) and expression of IFN-β. We present evidence that R(+)WIN55,212-2 strongly promotes the nuclear localization of IRF3. The potentiation of IFN-β expression by R(+)WIN55,212-2 is critical for manifesting its protective effects in the murine MS model EAE as evidenced by its reduced therapeutic efficacy in the presence of an anti-IFN-β antibody. R(+)WIN55,212-2 also induces IFN-β expression in MS patient peripheral blood mononuclear cells, whereas down-regulating inflammatory signaling in these cells. These findings identify R(+)WIN55,212-2 as a novel regulator of TLR3 signaling to IRF3 activation and IFN-β expression and highlights a new mechanism that may be open to exploitation in the development of new therapeutics for the treatment of MS. Description: PUBLISHED

Development of Allele-Specific Therapeutic siRNA in Meesmann Epithelial Corneal Dystrophy.

Sat, 01 Jan 2011 00:00:00 GMT

Title: Development of Allele-Specific Therapeutic siRNA in Meesmann Epithelial Corneal Dystrophy. Author: IRVINE, ALAN Abstract: BACKGROUND: Meesmann epithelial corneal dystrophy (MECD) is an inherited eye disorder caused by dominant-negative mutations in either keratins K3 or K12, leading to mechanical fragility of the anterior corneal epithelium, the outermost covering of the eye. Typically, patients suffer from lifelong irritation of the eye and/or photophobia but rarely lose visual acuity; however, some individuals are severely affected, with corneal scarring requiring transplant surgery. At present no treatment exists which addresses the underlying pathology of corneal dystrophy. The aim of this study was to design and assess the efficacy and potency of an allele-specific siRNA approach as a future treatment for MECD. METHODS AND FINDINGS: We studied a family with a consistently severe phenotype where all affected persons were shown to carry heterozygous missense mutation Leu132Pro in the KRT12 gene. Using a cell-culture assay of keratin filament formation, mutation Leu132Pro was shown to be significantly more disruptive than the most common mutation, Arg135Thr, which is associated with typical, mild MECD. A siRNA sequence walk identified a number of potent inhibitors for the mutant allele, which had no appreciable effect on wild-type K12. The most specific and potent inhibitors were shown to completely block mutant K12 protein expression with negligible effect on wild-type K12 or other closely related keratins. Cells transfected with wild-type K12-EGFP construct show a predominantly normal keratin filament formation with only 5% aggregate formation, while transfection with mutant K12-EGFP construct resulted in a significantly higher percentage of keratin aggregates (41.75%; p<0.001 with 95% confidence limits). The lead siRNA inhibitor significantly rescued the ability to form keratin filaments (74.75% of the cells contained normal keratin filaments; p<0.001 with 95% confidence limits). CONCLUSIONS: This study demonstrates that it is feasible to design highly potent siRNA against mutant alleles with single-nucleotide specificity for future treatment of MECD. Description: PUBLISHED

A TNF-Regulated Recombinatorial Macrophage Immune Receptor Implicated in Granuloma Formation in Tuberculosis

Sat, 01 Jan 2011 00:00:00 GMT

Title: A TNF-Regulated Recombinatorial Macrophage Immune Receptor Implicated in Granuloma Formation in Tuberculosis Author: KEANE, JOSEPH Abstract: Macrophages play a central role in host defense against mycobacterial infection and anti- TNF therapy is associated with granuloma disorganization and reactivation of tuberculosis in humans. Here, we provide evidence for the presence of a T cell receptor (TCR) αβ based recombinatorial immune receptor in subpopulations of human and mouse monocytes and macrophages. In vitro, we find that the macrophage-TCRαβ induces the release of CCL2 and modulates phagocytosis. TNF blockade suppresses macrophage-TCRαβ expression. Infection of macrophages from healthy individuals with mycobacteria triggers formation of clusters that express restricted TCR Vβ repertoires. In vivo, TCRαβ bearing macrophages abundantly accumulate at the inner host-pathogen contact zone of caseous granulomas from patients with lung tuberculosis. In chimeric mouse models, deletion of the variable macrophage-TCRαβ or TNF is associated with structurally compromised granulomas of pulmonary tuberculosis even in the presence of intact T cells. These results uncover a TNF-regulated recombinatorial immune receptor in monocytes/macrophages and demonstrate its implication in granuloma formation in tuberculosis. Description: PUBLISHED

Post-operative infection and sepsis in humans is associated with deficient gene expression of Yc cytokines and their apoptosis mediators.

Sat, 01 Jan 2011 00:00:00 GMT

Title: Post-operative infection and sepsis in humans is associated with deficient gene expression of Yc cytokines and their apoptosis mediators. Author: MC MANUS, ROSS; KELLEHER, DERMOT P; DOHERTY, DEREK; RYAN, THOMAS Abstract: INTRODUCTION: Lymphocyte homeostasis is dependent on the γc cytokines. We hypothesised that sepsis in humans is associated with differential gene expression of the γc cytokines and their associated apoptosis mediators. METHODS: The study population consisted of a total of 60 patients with severe sepsis, 15 with gram negative bacteraemia, 10 healthy controls and 60 patients undergoing elective lung resection surgery. Pneumonia was diagnosed by CDC NNIC criteria. Gene expression in peripheral blood leukocytes (PBLs) of interleukin (IL)-2, 7, 15 and interferon (IFN)-γ, Bax, Bim, Bcl-2 was determined by qRT-PCR and IL-2 and IL-7 serum protein levels by ELISA. Gene expression of IL-2, 7 and IFN-γ was measured in peripheral blood leukocytes (PBL), cultured in the presence of lipopolysacharide (LPS) and CD3 binding antibody (CD3ab) RESULTS: IL-2 gene expression was lower in the bacteraemia group compared with controls, and lower still in the sepsis group (P < 0.0001). IL-7 gene expression was similar in controls and bacteraemia, but lower in sepsis (P < 0.0001). IL-15 gene expression was similar in the three groups. Bcl-2 gene expression was less (P < 0.0001) and Bim gene expression was greater (P = 0.0003) in severe sepsis compared to bacteraemic and healthy controls. Bax gene expression was similar in the three groups.In lung resection surgery patients, post-operative pneumonia was associated with a perioperative decrease in IL-2 mRNA (P < 0.0001) and IL-7 mRNA (P = 0.003). IL-2 protein levels were reduced in sepsis and bacteraemia compared to controls (P = 0.02) but similar in pneumonia and non-pneumonia groups. IL-7 protein levels were similar in all groups.In cultured PBLs, IFN-γ gene expression was decreased in response to LPS and increased in response to CD3ab with sepsis: IL-7 gene expression increased in response to LPS in controls and to CD3ab with sepsis; Bcl-2 gene expression decreased in response to combined CD3ab and IL-2 with sepsis. CONCLUSIONS: Patients with infection and sepsis have deficient IL-2 and IL-7 gene expression in PBLs. Aberrant cytokine gene expression may precede the onset of infection. Description: PUBLISHED

Biomarkers of folate status in NHANES: a roundtable summary 1-6

Sat, 01 Jan 2011 00:00:00 GMT

Title: Biomarkers of folate status in NHANES: a roundtable summary 1-6 Author: MOLLOY, ANNE MARIE Abstract: A roundtable to discuss the measurement of folate status biomarkers in NHANES took place in July 2010. NHANES has measured serum folate since 1974 and red blood cell (RBC) folate since 1978 with the use of several different measurement procedures. Data on serum 5-methyltetrahydrofolate (5MTHF) and folic acid (FA) concentrations in persons aged ≥60 y are available in NHANES 1999–2002. The roundtable reviewed data that showed that folate concentrations from the Bio-Rad Quantaphase II procedure (Bio-Rad Laboratories, Hercules, CA; used in NHANES 1991–1994 and NHANES 1999–2006) were, on average, 29% lower for serum and 45% lower for RBC than were those from the microbiological assay (MA), which was used in NHANES 2007–2010. Roundtable experts agreed that these differences required a data adjustment for time-trend analyses. The roundtable reviewed the possible use of an isotope-dilution liquid chromatography–tandem mass spectrometry (LC-MS/MS) measurement procedure for future NHANES and agreed that the close agreement between the MA and LC-MS/MS results for serum folate supported conversion to the LC-MS/MS procedure. However, for RBC folate, the MA gave 25% higher concentrations than did the LC-MS/MS procedure. The roundtable agreed that the use of the LC-MS/MS procedure to measure RBC folate is premature at this time. The roundtable reviewed the reference materials available or under development at the National Institute of Standards and Technology and recognized the challenges related to, and the scientific need for, these materials. They noted the need for a commutability study for the available reference materials for serum 5MTHF and FA. Description: PUBLISHED