Iron status influences mitochondrial disease progression in Complex I-deficient mice

Mitochondrial dysfunction caused by aberrant Complex I assembly and reduced activity of the electron transport chain is pathogenic in many genetic and age-related diseases. Mice missing the Complex I subunit NADH dehydrogenase [ubiquinone] iron-sulfur protein 4 (NDUFS4) are a leading mammalian model of severe mitochondrial disease that exhibit many characteristic symptoms of Leigh Syndrome including oxidative stress, neuroinflammation, brain lesions, and premature death. NDUFS4 knockout mice have decreased expression of nearly every Complex I subunit. As Complex I normally contains at least 8 iron-sulfur clusters and more than 25 iron atoms, we asked whether a deficiency of Complex I may lead to iron perturbations, thereby accelerating disease progression. Consistent with this, iron supplementation accelerates symptoms of brain degeneration in these mice, while iron restriction delays the onset of these symptoms, reduces neuroinflammation, and increases survival. NDUFS4 knockout mice display signs of iron overload in the liver including increased expression of hepcidin and show changes in iron-responsive element-regulated proteins consistent with increased cellular iron that were prevented by iron restriction. These results suggest that perturbed iron homeostasis may contribute to pathology in Leigh Syndrome and possibly other mitochondrial disorders.

A Uniform Description of Perioperative Brain MRI Findings in Infants with Severe Congenital Heart Disease: Results of a European Collaboration

BACKGROUND AND PURPOSE

A uniform description of brain MR imaging findings in infants with severe congenital heart disease to assess risk factors, predict outcome, and compare centers is lacking. Our objective was to uniformly describe the spectrum of perioperative brain MR imaging findings in infants with congenital heart disease.

MATERIALS AND METHODS

Prospective observational studies were performed at 3 European centers between 2009 and 2019. Brain MR imaging was performed preoperatively and/or postoperatively in infants with transposition of the great arteries, single-ventricle physiology, or left ventricular outflow tract obstruction undergoing cardiac surgery within the first 6 weeks of life. Brain injury was assessed on T1, T2, DWI, SWI, and MRV. A subsample of images was assessed jointly to reach a consensus.

RESULTS

A total of 348 MR imaging scans (180 preoperatively, 168 postoperatively, 146 pre- and postoperatively) were obtained in 202 infants. Preoperative, new postoperative, and cumulative postoperative white matter injury was identified in 25%, 30%, and 36%; arterial ischemic stroke, in 6%, 10%, and 14%; hypoxic-ischemic watershed injury in 2%, 1%, and 1%; intraparenchymal cerebral hemorrhage, in 0%, 4%, and 5%; cerebellar hemorrhage, in 6%, 2%, and 6%; intraventricular hemorrhage, in 14%, 6%, and 13%; subdural hemorrhage, in 29%, 17%, and 29%; and cerebral sinovenous thrombosis, in 0%, 10%, and 10%, respectively.

CONCLUSIONS

A broad spectrum of perioperative brain MR imaging findings was found in infants with severe congenital heart disease. We propose an MR imaging protocol including T1-, T2-, diffusion-, and susceptibility-weighted imaging, and MRV to identify ischemic, hemorrhagic, and thrombotic lesions observed in this patient group.

Repeatability and reproducibility of multiparametric magnetic resonance imaging of the liver

As the burden of liver disease reaches epidemic levels, there is a high unmet medical need to develop robust, accurate and reproducible non-invasive methods to quantify liver tissue characteristics for use in clinical development and ultimately in clinical practice. This prospective cross-sectional study systematically examines the repeatability and reproducibility of iron-corrected T1 (cT1), T2*, and hepatic proton density fat fraction (PDFF) quantification with multiparametric MRI across different field strengths, scanner manufacturers and models. 61 adult participants with mixed liver disease aetiology and those without any history of liver disease underwent multiparametric MRI on combinations of 5 scanner models from two manufacturers (Siemens and Philips) at different field strengths (1.5T and 3T). We report high repeatability and reproducibility across different field strengths, manufacturers, and scanner models in standardized cT1 (repeatability CoV: 1.7%, bias -7.5ms, 95% LoA of -53.6 ms to 38.5 ms; reproducibility CoV 3.3%, bias 6.5 ms, 95% LoA of -76.3 to 89.2 ms) and T2* (repeatability CoV: 5.5%, bias -0.18 ms, 95% LoA -5.41 to 5.05 ms; reproducibility CoV 6.6%, bias -1.7 ms, 95% LoA -6.61 to 3.15 ms) in human measurements. PDFF repeatability (0.8%) and reproducibility (0.75%) coefficients showed high precision of this metric. Similar precision was observed in phantom measurements. Inspection of the ICC model indicated that most of the variance in cT1 could be accounted for by study participants (ICC = 0.91), with minimal contribution from technical differences. We demonstrate that multiparametric MRI is a non-invasive, repeatable and reproducible method for quantifying liver tissue characteristics across manufacturers (Philips and Siemens) and field strengths (1.5T and 3T).

Reference range of liver corrected T1 values in a population at low risk for fatty liver disease-a UK Biobank sub-study, with an appendix of interesting cases

Purpose

Corrected T1 (cT1) value is a novel MRI-based quantitative metric for assessing a composite of liver inflammation and fibrosis. It has been shown to distinguish between non-alcoholic fatty liver disease (NAFL) and non-alcoholic steatohepatitis. However, these studies were conducted in patients at high risk for liver disease. This study establishes the normal reference range of cT1 values for a large UK population, and assesses interactions of age and gender.

Methods

MR data were acquired on a 1.5 T system as part of the UK Biobank Imaging Enhancement study. Measures for Proton Density Fat Fraction and cT1 were calculated from the MRI data using a multiparametric MRI software application. Data that did not meet quality criteria were excluded from further analysis. Inter and intra-reader variability was estimated in a set of data. A cohort at low risk for NAFL was identified by excluding individuals with BMI ≥ 25 kg/m² and PDFF ≥ 5%. Of the 2816 participants with data of suitable quality, 1037 (37%) were classified as at low risk.

Results

The cT1 values in the low-risk population ranged from 573 to 852 ms with a median of 666 ms and interquartile range from 643 to 694 ms. Iron correction of T1 was necessary in 36.5% of this reference population. Age and gender had minimal effect on cT1 values.

Conclusion

The majority of cT1 values are tightly clustered in a population at low risk for NAFL, suggesting it has the potential to serve as a new quantitative imaging biomarker for studies of liver health and disease.

Utility and variability of three non-invasive liver fibrosis imaging modalities to evaluate efficacy of GR-MD-02 in subjects with NASH and bridging fibrosis during a phase-2 randomized clinical trial

BACKGROUND

Given the worldwide prevalence of NAFLD and NASH, there is a need to develop treatments to slow or reverse disease progression. GR-MD-02 (galactoarabino-rhamnogalaturonate) has been shown to reduce hepatic fibrosis in animal studies, and lower serum biomarkers of NASH fibrogenesis in humans. The primary aim of this study was to determine the difference between four-months of treatment with GR-MD-02 or placebo in liver inflammation and fibrosis as measured by iron-corrected T1 (cT1) mapping, a non-invasive magnetic resonance imaging (MRI) biomarker that correlates with the extent of hepatic fibro-inflammatory disease. The secondary aims were to determine change in liver stiffness as measured by magnetic resonance elastography (MRE) and shear-wave ultrasonic elastography (LSM), and to explore test-retest repeatability of the three biomarkers.

MATERIALS AND METHODS

Thirty subjects (13 females, 46-71 years) with NASH and advanced fibrosis were recruited. Subjects were randomized to receive 8 mg.kg-1 GR-MD-02 (via IV infusion) or placebo, administered biweekly over a 16-week period. Therapeutic efficacy was examined using cT1, MRE, and LSM. Statistical analyses on group differences in the biomarkers were performed using robust ANCOVA models adjusting for baseline measurement and additional covariates.

RESULTS

There was no significant difference in cT1 (p = 0.16) between GR-MD-02 and placebo groups following a 16-week intervention. There was also no significant difference in liver stiffness, measured by MRE (p = 0.80) or LSM (p = 0.63), between groups. Examination of repeatability of the cT1, MRE and LSM revealed coefficient of variations of 3.1%, 11% and 40% respectively.

CONCLUSIONS

8 mg.kg-1 of GR-MD-02 had no significant effect on non-invasive biomarkers of liver inflammation or fibrosis over a 4-month period. Histological confirmation was not available in this study. The high reproducibility of the primary outcome measure suggests that cT1 could be utilized for monitoring longitudinal change in patients with NASH.

Multiparametric magnetic resonance imaging for quantitation of liver disease: a two-centre cross-sectional observational study

LiverMultiScan is an emerging diagnostic tool using multiparametric MRI to quantify liver disease. In a two-centre prospective validation study, 161 consecutive adult patients who had clinically-indicated liver biopsies underwent contemporaneous non-contrast multiparametric MRI at 3.0 tesla (proton density fat fraction (PDFF), T1 and T2* mapping), transient elastography (TE) and Enhanced Liver Fibrosis (ELF) test. Non-invasive liver tests were correlated with gold standard histothological measures. Reproducibility of LiverMultiScan was investigated in 22 healthy volunteers. Iron-corrected T1 (cT1), TE, and ELF demonstrated a positive correlation with hepatic collagen proportionate area (all p < 0·001). TE was superior to ELF and cT1 for predicting fibrosis stage. cT1 maintained good predictive accuracy for diagnosing significant fibrosis in cases with indeterminate ELF, but not for cases with indeterminate TE values. PDFF had high predictive accuracy for individual steatosis grades, with AUROCs ranging from 0.90-0.94. T2* mapping diagnosed iron accumulation with AUROC of 0.79 (95% CI: 0.67-0.92) and negative predictive value of 96%. LiverMultiScan showed excellent test/re-test reliability (coefficients of variation ranging from 1.4% to 2.8% for cT1). Overall failure rates for LiverMultiScan, ELF and TE were 4.3%, 1.9% and 15%, respectively. LiverMultiScan is an emerging point-of-care diagnostic tool that is comparable with the established non-invasive tests for assessment of liver fibrosis, whilst at the same time offering a superior technical success rate and contemporaneous measurement of liver steatosis and iron accumulation.

Utility and cost evaluation of multiparametric magnetic resonance imaging for the assessment of non-alcoholic fatty liver disease

BACKGROUND

Validated diagnostic tools that are accurate, cost effective and acceptable to patients are required for disease stratification and monitoring in NAFLD.

AIMS

To investigate the performance and cost of multiparametric MRI alongside existing biomarkers in the assessment of NAFLD.

METHODS

Adult patients undergoing standard of care liver biopsy for NAFLD were prospectively recruited at two UK liver centres and underwent multiparametric MRI, blood sampling and transient elastography withing 2 weeks of liver biopsy. Non-invasive markers were compared to histology as the gold standard.

RESULTS

Data were obtained in 50 patients and 6 healthy volunteers. Corrected T1 (cT1) correlated with NAFLD activity score (ρ = 0.514, P < .001). cT1, enhanced liver fibrosis (ELF) test and liver stiffness differentiated patients with simple steatosis and NASH with AUROC (95% CI) of 0.69 (0.50-0.88), 0.87 (0.77-0.79) and 0.82 (0.70-0.94) respectively and healthy volunteers from patients with AUROC (95% CI) of 0.93 (0.86-1.00), 0.81 (0.69-0.92) and 0.89 (0.77-1.00) respectively. For the risk stratification of NAFLD, multiparametric MRI could save £150,218 per 1000 patients compared to biopsy. Multiparametric MRI did not discriminate between individual histological fibrosis stages in this population (P = .068).

CONCLUSIONS

Multiparametric MRI accurately identified patients with steatosis, stratifies those with NASH or simple steatosis and reliably excludes clinically significant liver disease with superior negative predictive value (83.3%) to liver stiffness (42.9%) and ELF (57.1%). For the risk stratification of NAFLD, multiparametric MRI was cost effective and, combined with transient elastography, had the lowest cost per correct diagnosis.

The anti-malarial atovaquone increases radiosensitivity by alleviating tumour hypoxia

Tumour hypoxia renders cancer cells resistant to cancer therapy, resulting in markedly worse clinical outcomes. To find clinical candidate compounds that reduce hypoxia in tumours, we conduct a high-throughput screen for oxygen consumption rate (OCR) reduction and identify a number of drugs with this property. For this study we focus on the anti-malarial, atovaquone. Atovaquone rapidly decreases the OCR by more than 80% in a wide range of cancer cell lines at pharmacological concentrations. In addition, atovaquone eradicates hypoxia in FaDu, HCT116 and H1299 spheroids. Similarly, it reduces hypoxia in FaDu and HCT116 xenografts in nude mice, and causes a significant tumour growth delay when combined with radiation. Atovaquone is a ubiquinone analogue, and decreases the OCR by inhibiting mitochondrial complex III. We are now undertaking clinical studies to assess whether atovaquone reduces tumour hypoxia in patients, thereby increasing the efficacy of radiotherapy.

Multiparametric magnetic resonance imaging predicts clinical outcomes in patients with chronic liver disease

BACKGROUND & AIMS

Multiparametric magnetic resonance (MR) imaging has been demonstrated to quantify hepatic fibrosis, iron, and steatosis. The aim of this study was to determine if MR can be used to predict negative clinical outcomes in liver disease patients.

METHODS

Patients with chronic liver disease (n=112) were recruited for MR imaging and data on the development of liver related clinical events were collected by medical records review. The median follow-up was 27months. MR data were analysed blinded for the Liver Inflammation and Fibrosis score (LIF; <1, 1-1.99, 2-2.99, and ⩾3 representing normal, mild, moderate, and severe liver disease, respectively), T2∗ for liver iron content and proportion of liver fat. Baseline liver biopsy was performed in 102 patients.

RESULTS

Liver disease aetiologies included non-alcoholic fatty liver disease (35%) and chronic viral hepatitis (30%). Histologically, fibrosis was mild in 54 (48%), moderate in 17 (15%), and severe in 31 (28%) patients. Overall mortality was 5%. Ten patients (11%) developed at least one liver related clinical event. The negative predictive value of LIF<2 was 100%. Two patients with LIF 2-2.99 and eight with LIF⩾3 had a clinical event. Patients with LIF⩾3 had a higher cumulative risk for developing clinical events, compared to those with LIF<1 (p=0.02) and LIF 1-1.99 (p=0.03). Cox regression analysis including all 3 variables (fat, iron, LIF) resulted in an enhanced LIF predictive value.

CONCLUSIONS

Non-invasive standardised multiparametric MR technology may be used to predict clinical outcomes in patients with chronic liver disease.

Improved Methods to Generate Spheroid Cultures from Tumor Cells, Tumor Cells & Fibroblasts or Tumor-Fragments: Microenvironment, Microvesicles and MiRNA

Diagnostic and prognostic indicators are key components to achieve the goal of personalized cancer therapy. Two distinct approaches to this goal include predicting response by genetic analysis and direct testing of possible therapies using cultures derived from biopsy specimens. Optimally, the latter method requires a rapid assessment, but growing xenograft tumors or developing patient-derived cell lines can involve a great deal of time and expense. Furthermore, tumor cells have much different responses when grown in 2D versus 3D tissue environments. Using a modification of existing methods, we show that it is possible to make tumor-fragment (TF) spheroids in only 2–3 days. TF spheroids appear to closely model characteristics of the original tumor and may be used to assess critical therapy-modulating features of the microenvironment such as hypoxia. A similar method allows the reproducible development of spheroids from mixed tumor cells and fibroblasts (mixed-cell spheroids). Prior literature reports have shown highly variable development and properties of mixed-cell spheroids and this has hampered the detailed study of how individual tumor-cell components interact. In this study, we illustrate this approach and describe similarities and differences using two tumor models (U87 glioma and SQ20B squamous-cell carcinoma) with supporting data from additional cell lines. We show that U87 and SQ20B spheroids predict a key microenvironmental factor in tumors (hypoxia) and that SQ20B cells and spheroids generate similar numbers of microvesicles. We also present pilot data for miRNA expression under conditions of cells, tumors, and TF spheroids.

Glucose-lactate metabolic cooperation in cancer: insights from a spatial mathematical model and implications for targeted therapy

A recent study has hypothesised a glucose-lactate metabolic symbiosis between adjacent hypoxic and oxygenated regions of a developing tumour, and proposed a treatment strategy to target this symbiosis. However, in vivo experimental support remains inconclusive. Here we develop a minimal spatial mathematical model of glucose-lactate metabolism to examine, in principle, whether metabolic symbiosis is plausible in human tumours, and to assess the potential impact of inhibiting it. We find that symbiosis is a robust feature of our model system-although on the length scale at which oxygen supply is diffusion-limited, its occurrence requires very high cellular metabolic activity-and that necrosis in the tumour core is reduced in the presence of symbiosis. Upon simulating therapeutic inhibition of lactate uptake, we predict that targeted treatment increases the extent of tissue oxygenation without increasing core necrosis. The oxygenation effect is correlated strongly with the extent of wild-type hypoxia and only weakly with wild-type symbiotic behaviour, and therefore may be promising for radiosensitisation of hypoxic, lactate-consuming tumours even if they do not exhibit a spatially well-defined symbiosis. Finally, we conduct in vitro experiments on the U87 glioblastoma cell line to facilitate preliminary speculation as to where highly malignant tumours might fall in our parameter space, and find that these experiments suggest a weakly symbiotic regime for U87 cells, thus raising the new question of what relationship might exist between symbiosis and tumour malignancy.

Regulation of O2 consumption by the PI3K and mTOR pathways contributes to tumor hypoxia

BACKGROUND

Inhibitors of the phosphatidylinositol 3-kinase (PI3K) and the mammalian target of rapamycin (mTOR) pathway are currently in clinical trials. In addition to antiproliferative and proapoptotic effects, these agents also diminish tumor hypoxia. Since hypoxia is a major cause of resistance to radiotherapy, we sought to understand how it is regulated by PI3K/mTOR inhibition.

METHODS

Whole cell, mitochondrial, coupled and uncoupled oxygen consumption were measured in cancer cells after inhibition of PI3K (Class I) and mTOR by pharmacological means or by RNAi. Mitochondrial composition was assessed by immunoblotting. Hypoxia was measured in spheroids, in tumor xenografts and predicted with mathematical modeling.

RESULTS

Inhibition of PI3K and mTOR reduced oxygen consumption by cancer cell lines is predominantly due to reduction of mitochondrial respiration coupled to ATP production. Hypoxia in tumor spheroids was reduced, but returned after removal of the drug. Murine tumors had increased oxygenation even in the absence of average perfusion changes or tumor necrosis.

CONCLUSIONS

Targeting the PI3K/mTOR pathway substantially reduces mitochondrial oxygen consumption thereby reducing tumor hypoxia. These alterations in tumor hypoxia should be considered in the design of clinical trials using PI3K/mTOR inhibitors, particularly in conjunction with radiotherapy.

3D tumour spheroids as a model to assess the suitability of [18F]FDG-PET as an early indicator of response to PI3K inhibition

BACKGROUND

[18F] Fluorodeoxyglucose Positron Emission Tomography ([18F]FDG-PET) is widely used to monitor response to therapy in the clinic and has, more recently, been proposed as an early marker of long term response. This relies on the assumption that a change in glucose consumption parallels a reduction in viability and long term growth potential. However, cells may utilise substrates other than glucose and as many therapeutics interfere with glucose metabolism directly, it is entirely plausible that a positive [18F]FDG-PET response may be unrelated to long term growth. Furthermore, changes in metabolism and proliferation may take place on different temporal scales, thus restricting the time window in which [18F]FDG-PET is predictive. The PI3K oncogenic signalling pathway is a master regulator of multiple cellular processes including glucose metabolism, proliferation and cell survival. Inhibition of PI3K has been shown to reduce [18F]FDG uptake in several tumour types but the relative influence of this pathway on glucose metabolism and proliferation is not fully established.

AIM

We proposed to (i) assess the suitability of [18F]FDG as a tracer for measuring response to PI3K inhibition and (ii) determine the optimum imaging schedule, in vitro. We used multicellular tumour spheroids, an excellent 3D in vitro model of avascular tumours, to investigate the effects of the PI3K inhibitors, NVP-BKM120 and NVP-BEZ235, on [18F]FDG uptake and its relation to 3D growth.

METHODS

Spheroids were prepared from two cell lines with a constitutively active PI3K/Akt pathway, EMT6 (highly proliferative mouse mammary) and FaDu (moderately proliferate human nasopharyngeal). Treatment consisted of a 24h exposure to either inhibitor, and growth was monitored over the following 7 days. To mimic potential imaging regimens with [18F]FDG-PET, average [18F]FDG uptake per viable cell was measured (a) directly following the 24h exposure, (b) following an additional 24h recovery period, or (c) following a 48 h exposure.

RESULTS

Growth was restricted significantly (p<0.0001) in a dose-dependent fashion in spheroids from both cell lines treated with either inhibitor. In the highly proliferative cell line EMT6, [18F]FDG uptake was significantly reduced at all concentrations of inhibitor. For the moderately proliferative cell line FaDu, [18F]FDG was affected in a dose-dependent fashion, but to lesser degree. To assess the predictivity of [18F]FDG uptake for long term growth restriction, Pearson correlation coefficients were calculated for each imaging regimen. These indicated that the optimal imaging schedules differed between cell lines.

CONCLUSION

This study suggests that [18F]FDG may be a suitable marker of response to PI3K inhibition in the cell lines that we have studied. Our data support the hypothesis that imaging schedules should be optimised on a tumour type-specific basis.

Insulin-like growth factor binding protein-1 in PCOS: a systematic review and meta-analysis

BACKGROUND

Despite extensive research, the pathogenesis of polycystic ovary syndrome (PCOS) remains unclear. Putatively, an elevated circulating concentration of insulin inhibits the production of insulin-like growth factor binding protein-1 (IGFBP-1), thus increasing the level of free IGF-I in serum and stimulating ovarian androgen production. Decreased IGFBP-1 has been reported in PCOS and in obesity; however, there are inconsistencies in the evidence. This systematic review and meta-analysis aimed to determine whether IGFBP-1 is decreased in PCOS when controlling for the influence of BMI.

METHODS

Articles published between 1988 and 2008 were searched using MEDLINE, PubMed, SCOPUS and Web of Knowledge. Unpublished literature, trials in progress, and recent reviews were also searched. Original articles were selected by two investigators. To be included, the study must have compared serum IGFBP-1 in two populations: either PCOS versus controls, or an overweight subgroup versus the normal weight subgroup in either population. From 617 identified articles, 12 were included in the meta-analysis. Data were abstracted by two reviewers independently and standardized for errors.

RESULTS

The population difference is presented as the Weighted Mean Difference (95% CI). PCOS subjects had a significantly lower serum concentrations of IGFBP-1 compared with controls [P< 0.00001; -36.6 (-52.0, -21.2) µg/l]. Overweight PCOS subjects also had lower IGFBP-1 levels compared with normal weight PCOS subjects [P < 0.006; -30.6 (-52.3, -8.8) µg/l]. No significant difference was found between overweight PCOS patients and overweight controls [P = 0.23; -5.1 (-13.5, 3.2) µg/l] or between normal weight PCOS patients and normal weight controls [P = 0.50; -3.8 (-14.9, 7.3) µg/l]. Overweight controls had significantly lower IGFBP-1 concentrations than normal weight controls [P = 0.03; -18.0 (-34.4, - 1.5) µg/l].

CONCLUSION

These data indicate that a decreased serum level of IGFBP-1 is unlikely to be a mechanism for ovarian hyperandrogenism in PCOS. BMI may be the major determinant of serum IGFBP-1.

Brown colour in natural diamond and interaction between the brown related and other colour-inducing defects

Absorption spectroscopy results on a range of type II diamonds are presented which enable the electronic states associated with them to be mapped out. High pressure, high temperature treatment of brown type IIa diamonds has enabled an activation energy for the removal of the brown colour of 8.0 ± 0.3 eV to be determined and this is consistent with expectations associated with the currently accepted vacancy cluster model for the defect. Theoretical calculations suggest that this defect will generate partially filled gap states about 1 eV above the valence band. Data on the photochromic behaviour of bands producing pink colour and their relation to brown colour are presented; these suggest that the pink bands are produced from two independent transitions with ground states close to each other just below the middle of the band gap. Compensation of neutral boron by charge transfer from states associated with brown colour is demonstrated via the correlated increase in neutral boron and decrease in brown colour on high pressure, high temperature treatment to remove the defects causing the brown colour.

Properties of optically active vacancy clusters in type IIa diamond

In this paper we report on the positron lifetime results obtained for brown and colourless natural diamond. Optical effects of the observed vacancy defects in brown, high pressure, high temperature (HPHT) treated colourless and naturally colourless type IIa diamond samples were studied by combining the positron measurement with monochromatic illumination. Brown diamond was found to contain optically active vacancy clusters (40-60 missing atoms) strongly correlated with the optical absorption spectra. The optical activity of these vacancy clusters is manifested by a photo-excitation induced change of charge from neutral to negative. The clusters gradually disappear during the HPHT treatments, and the samples treated at 2500 °C resemble colourless samples optically and show similar positron lifetimes. The results show that the brown colour originates from the vacancy clusters and that their removal by the HPHT treatment causes the loss of coloration.

Concurrent colorectal malignancy and abdominal aortic aneurysm: a multicentre experience and review of the literature

OBJECTIVES

There is lack of consensus regarding concurrent vs. staged approaches, and the prioritisation of staged procedures in cases presenting with colorectal carcinoma (CRC) and abdominal aortic aneurysm (AAA) synchronously. We aim to present our experience, review the literature on this therapeutic dilemma and examine the role of endovascular aortic repair (EVAR).

DESIGN, MATERIALS AND METHODS

An observational study of the experience of two centres and a systematic review of the published literature.

RESULTS

Twenty-four patients were identified from the prospective databases of two tertiary referral centres between 2001 and 2006. Intervention for both malignancy and aneurysm was performed in 13 patients. In 10 patients, cancer resection was performed initially and was followed by open aneurysm repair (n=3) or EVAR (n=7). Two patients (AAA diameters: 7.0 and 8.0cm) underwent EVAR prior to colonic resection. One patient was selected for synchronous surgery. There were no interval AAA ruptures, graft infection or postoperative mortalities. Literature review identified 269 such cases; of these 101 were treated by combined surgery. In staged surgery, there were nine interval aneurysmal ruptures and one aortic graft infection.

CONCLUSIONS

In our experience, staged management can be undertaken, without interval aneurysmal rupture. EVAR has an evolving role in preventing delay in CRC management, in high-risk patients, and during combined intervention.

Therapeutic immune regulation in experimental interstitial nephritis with suppressor T cells and their soluble factors

The therapeutic application of immune regulation and suppressor T cells to the control and modulation of autoimmune disease is an area of growing experimental interest. Our group has been studying experimental interstitial nephritis, both to better understand the disease process itself and to test immunoregulatory strategies for their inhibitory and protective effects. This report gives a brief overview of this work.

A model to simulate tumour oxygenation and dynamic [18F]-Fmiso PET data

The microenvironment of a tumour, in particular its hypoxic status, is a crucial factor in its response to radiotherapy. Conventional techniques for measuring hypoxia are either invasive or follow surgical intervention, and thus not ideal. Positron emission tomography allows the non-invasive pre-surgical assessment of oxygen status by measuring the spatiotemporal distribution of hypoxia-specific tracers. However, the relationship between levels of uptake and the underlying oxygen tension are yet to be elucidated. Furthermore, it is not fully understood how changes in the underlying physiology affect the appearance of uptake. This paper presents a modular simulation of the tumour microenvironment, underpinned by a probability density function (PDF) to model the vasculature. The model is solved numerically, to simulate both the steady-state oxygenation of a tumour and the spatiotemporal distribution of the hypoxia-specific tracer, [18F]-fluoromisonidazole (Fmiso), in a 2D environment. The results show that using a PDF to represent the vasculature effectively captures the 'hypoxic island' appearance of oxygen-deficient tissues seen ex vivo. Simulated tissue activity curves (TACs) demonstrate the general two-stage trend of empirical data, with an initial perfusion-dominated uptake, followed by hypoxia-specific binding. In well-perfused tissue, activity follows plasma levels in early stages, with binding of Fmiso only becoming apparent at a later stage. In structurally hypoxic tissue, a more gradual initial increase in activity is observed, followed by the same accumulation slope. We demonstrate the utility of theoretical modelling of tracer uptake, by quantifying the changes in TAC structure that arise as a result of altering key physiological characteristics. For example, by decreasing either the proximity of tissue to the vasculature, or the effective diffusion coefficient of Fmiso, we can observe a shift of TAC structure from corresponding to well-perfused to avascular regions, despite wholly different underlying causes.

Unicentric Castleman's disease: a surprising neck mass

BACKGROUND

We present the case of a 36-year-old female with a three-week history of a pulsatile, tender mass in the anterior triangle of the neck.

METHODS

Radiology demonstrated that this was a vascular tumour deep to the sternocleidomastoid muscle.

RESULTS

Pre-operative embolisation and complete surgical resection was performed. Histology revealed Castleman's disease.

CONCLUSION

Unicentric hyaline vascular Castleman's disease is an unusual cause of neck mass. Surgical resection remains the best chance for cure in unicentric disease. Long term follow-up is necessary as the risk of subsequent malignancy exists.

Hydroxymethylglutaryl co-enzyme A reductase inhibition attenuates endotoxin-mediated inflammatory responses

Background

The aim of this study was to investigate whether inhibition of hydroxymethylglutaryl co-enzyme A reductase attenuates leucocyte–endothelial cell interactions and alters expression of endothelial constitutive nitric oxide synthase (ecNOS) and inducible nitric oxide synthase (iNOS) following exposure to endotoxin.

Methods

Male Sprague–Dawley rats were randomized into control, lipopolysaccharide (LPS) and pravastatin + LPS groups (seven per group). Pravastatin sodium was gavaged at 0·4 mg per kg per day for 5 days, after which LPS 15 mg/kg was administered via the jugular vein. Intravital microscopy was used to determine leucocyte–endothelial cell interactions.

Results

Following the administration of LPS there was a significant reduction in leucocyte rolling velocity at 10 min (mean(s.e.m.) 69(3) versus 102(6) per cent of baseline value; P = 0·041), an increase in the number of adherent leucocytes at 10 min (4·5(0·5) versus 2·8(0·3) per 100 µm; P = 0·044) and an increase in the number of leucocytes undergoing transendothelial migration at 30 min (4·2(0·4) versus 1·7(0·4) per field; P = 0·008) compared with controls. Pretreatment with pravastatin significantly attenuated LPS-induced leucocyte–endothelial cell interactions (rolling velocity 89(6) per cent at 10 min, P = 0·038; adherent leucocytes 3·0(0·5) per 100 µm at 10 min, P = 0·038; migrating leucocytes 1·9(0·5) per field at 30 min, P = 0·001). This endothelial protection was associated with maintenance of ecNOS and reduced iNOS expression within mesenteric tissues.

Conclusion

These data show that pravastatin produces anti-inflammatory effects in response to injurious stimuli by attenuation of leucocyte–endothelial cell interactions.

The therapeutic role of taurine in ischaemia-reperfusion injury

As a non-toxic endogenous antioxidant, the semi-essential amino acid taurine is a potential attenuator of oxidative damage such as that produced by ischaemia-reperfusion injury. Ischaemia-reperfusion injury is a well established if paradoxical phenomenon whereby ischaemic tissue, doomed to necrosis if it is not reperfused, is actually further damaged by oxidative attack when perfusion is restored. This paper is a review of the literature concerning therapeutic strategies in ischaemia-reperfusion injury, including non-pharmacological and pharmacological interventions. There is consistent experimental evidence of an important role of taurine in ischaemia-reperfusion injury, with a clinical role emerging in human trials of taurine administered prior to coronary artery bypass grafting and heart valve surgery.

Hydroxy-methylglutaryl-coenzyme A reductase inhibition improves endothelial dysfunction in type-1 diabetes

OBJECTIVE

We hypothesize that treatment with Pravastatin, a HMG CoA reductase inhibitor would improve flow-mediated dilation (FMD), a nitric oxide dependent phenomenon and the earliest detectable marker of endothelial dysfunction, in asymptomatic patients with type-1 diabetes.

MATERIALS AND METHODS

FMD of the brachial artery in response to reactive hyperaemia was measured using high-resolution ultrasonography. Young male patients with type-1 diabetes (n=9) were compared with age matched non-diabetic controls (n=8).

RESULTS

The FMD response in the control group was a median increase in diameter of 7.9 (range 3.8-12.6)%. In the diabetic group the FMD response was impaired when compared with controls with a median increase only of 4.4 (range 3.7-5.8)% (p<0.01). Following Pravastatin, 40 mg per day for one month in the diabetic group, there was a significant diameter change in response to reactive hyperaemia with a median of 8.4 (range 6.9-12.6)% (p<0.01).

CONCLUSIONS

These data confirm the presence of endothelial dysfunction in young patients with type-1 diabetes. We have shown that 1-month of Pravastatin treatment normalizes FMD. This suggests that HMG CoA reductase inhibitors may have a role in the management of diabetes mellitus, even in the presence of normal serum cholesterol levels.

Taurine and vitamin C modify monocyte and endothelial dysfunction in young smokers

BACKGROUND

Endothelial dysfunction initiated by monocyte-endothelial interactions has previously been observed in many vasculopathies, including chronic cigarette smoking. Taurine, a semiessential amino acid, and vitamin C, a naturally occurring antioxidant, have previously been shown to have endothelial protective effects when exposed to proinflammatory insults. Therefore, we hypothesized that taurine and vitamin C would restore endothelial function in young smokers by modifying monocyte-endothelial interactions.

METHODS AND RESULTS

Endothelial-dependent vasodilatation was assessed in vivo using duplex ultrasonography, and monocyte-endothelial interactions were assessed in vitro using endothelial cell culture (human umbilical vein endothelial cells [HUVECs]) with monocyte-conditioned medium (MCM). Endothelial-dependent vasodilatation was significantly impaired in young smokers compared with nonsmokers. Pretreatment of young smokers for 5 days with 2 g/d vitamin C and, more significantly, with 1.5 g/d taurine attenuated this response. MCM taken from smokers impaired the release of nitric oxide and increased the levels of endothelin-1 release from HUVECs. When HUVECs were cultured with MCM from smokers who had been treated with taurine, the levels of nitric oxide and endothelin-1 returned toward control levels. This was attributed to an upregulation in endothelial nitric oxide synthase expression.

CONCLUSIONS

These observations suggest that taurine supplementation has a beneficial impact on macrovascular endothelial function, and an investigation of its effect on altered endothelial function in dyslipidemic states is warranted.

Pharmacological induction of HSP27 attenuates intimal hyperplasia in vivo

OBJECTIVES

intimal hyperplasia (IH) is a major cause of re-stenosis post-vascular intervention. Induction of heat shock proteins (HSPs), by thermal pre-conditioning, reduces IH. Our aim was to investigate the effect of the pharmacological HSP inducer herbimycin A on IH in the rat carotid balloon injury model.

MATERIALS AND METHODS

thirty male Sprague-Dawley rats were randomized into three groups. All groups underwent balloon injury to the left carotid artery. Stress proteins were induced 18 h pre-operatively by heat shock or herbimycin A. Two weeks post-operatively, animals were sacrificed and carotid intima/media area ratio (I/M ratio) calculated using computerized planimetry. Neo-intimal proliferation was assessed immunohistochemically with PCNA (proliferating cell nuclear antigen). Western blot and immunohistochemistry for arterial HSP70 and HSP27 were performed.

RESULTS

heat stress and herbimycin significantly reduced the I/M ratio (p < 0.05 vs balloon injury alone). Neo-intimal proliferation was significantly reduced in the heat stress and herbimycin groups (p < 0.05 vs balloon injury alone). Heat stress induced arterial HSP70 and HSP27. Herbimycin A increased arterial HSP27.

CONCLUSION

herbimycin A significantly attenuates IH after balloon injury. HSP27 may be the HSP involved in mediating this response. Pharmacological inducers of HSPs may have a therapeutic role to play in preventing re-stenosis post-vascular intervention.

Clinically relevant thermal preconditioning attenuates ischemia-reperfusion injury

INTRODUCTION

Thermal preconditioning has previously been shown to attenuate ischemia-reperfusion induced injuries, possible due to increased expression of heat shock proteins (HSP). The model of thermal preconditioning used, however, was not clinically relevant as preconditioning was to 41 degrees C, leading to cellular damage. Our aim was thus to establish a novel and clinically applicable method of preconditioning.

MATERIALS AND METHODS

Twenty-six male Sprague-Dawley rats were split into three groups (nine control, nine ischemia-reperfusion, and eight preconditioned followed by ischemia-reperfusion). To precondition the animals, they were anesthetized and, using a water bath, their core temperature was raised by 1 degrees C for 15 min once a day for five successive days. I/R injury consisted of 30 min of aortic cross-clamping followed by 120 min of reperfusion; control animals had a laparotomy only. Indicators of lung injury were tissue myeloperoxidase, broncho-alveolar lavage protein concentration, and tissue edema. Tissue heat shock protein expression was detected by Western blot analysis.

RESULTS

Lower torso ischemia-reperfusion causes significant lung injury versus control, with raised levels of myeloperoxidase 4.53 iu/g to 7.88 iu/g (P < 0.05), raised B.A.L. protein concentration 419 microg/ml to 684 microg/ml (P < 0.05) and altered wet dry ratio 4.63 to 5.50. Clinically relevant thermal preconditioning attenuates all of these parameters back to control levels: myeloperoxidase 3.87 iu/g (P < 0.05 vs I/R), B.A.L. to 284 microg/ml (P < 0.01 vs I/R) and wet dry ratio to 4.44 (P < 0.05 vs I/R). Western blot demonstrated increased expression of H.S.P. 72 in the preconditioned group versus control and I/R alone. Western blot demonstrated increased expression of HSP72 in the preconditioned group vs control and I/R alone.

CONCLUSIONS

We conclude that clinically applicable thermal preconditioning can attenuate ischemia-reperfusion induced lung injury, possibly through increased expression of HSP72.

The activated sludge biomolecular database

Tremendous advances have recently been made in the development of molecular tools for analysis of microbial populations in the environment. However, an appropriate scientific basis for quantification of new molecular data must exist to effectively use these tools toward increased understanding of complex waste treatment environments and implementation of corrective actions to maintain or improve system performance. In particular, molecular tools are gaining widespread use in the study of activated-sludge microbial communities and have the potential to improve monitoring and control of wastewater treatment processes. The authors have created a Web-accessible database, the Activated Sludge Biomolecular Database, which provides a scientific basis for interpreting activated-sludge biomolecular information. The database achieves its goal by accumulating and disseminating a large body of knowledge relating the presence and quantity of specific biomolecules to process design, operating conditions, and wastewater characteristics.

A toxicity testing protocol using a bioluminescent reporter bacterium from activated sludge

A protocol for production, storage, and use of Shock 1 (Shk1) bioreporter cells for toxicity monitoring in wastewater treatment facilities was developed. Shk1 is a bioluminescent toxicity bioreporter for activated sludge previously constructed by the incorporation of lux genes into an activated sludge microorganism.A number of factors affecting Shk1 growth and bioluminescence were examined including the growth medium, tetracycline concentration, storage conditions, and test media. Based on the results of these experiments, a toxicity testing protocol was developed that involved growth of cultures in nutrient broth with tetracycline, storage of cultures at 4 degrees C, cell activation by reinoculation into nutrient broth, and toxicity testing by cell injection into the test media. Effective use of this approach required standardized time intervals for cell growth, storage, activation and exposure in the test media. Bioluminescence from Shk1 cells was measured in nutrient broth and influent wastewater and activated sludge mixed liquor from a municipal wastewater treatment plant. Using the Shk1 toxicity testing protocol, Zn EC(50) values for bioluminescence in nutrient broth, influent wastewater, and activated sludge mixed liquor were approximately 42, 7, and 32 mg/l, respectively. Zn concentrations as low as 1 mg/l could be detected in influent wastewater. The detection limit in influent wastewater is below the Zn concentrations typically reported to affect the activated sludge process.

Diethylmaleate, a pro-oxidant, attenuates experimental ischaemia-reperfusion-induced lung injury

BACKGROUND

Systemic ischaemia-reperfusion (IR) injury is in part an oxidant injury mediated by neutrophils. Diethylmaleate (DEM), an intracellular pro-oxidant agent, has been shown to alleviate neutrophil-mediated tissue injury. The aim of this study was to evaluate whether DEM could have a protective effect on neutrophil-mediated lung injury in an animal model of lower-torso IR.

METHODS

Sprague-Dawley rats (seven per group) were randomized into three groups. The control group underwent midline laparotomy only; the IR group underwent laparotomy and clamping of the infrarenal abdominal aorta for 30 min followed by 2 h of reperfusion; and the third group was pretreated with DEM 6 mmol/kg intraperitoneally 1 h before the IR insult.

RESULTS

IR resulted in a significant increase in both microvascular leakage and pulmonary neutrophil infiltration as measured by bronchoalveolar lavage protein concentration and pulmonary myeloperoxidase activity respectively. Pretreatment with DEM significantly attenuated both microvascular leakage and neutrophil infiltration.

CONCLUSION

Preconditioning with DEM protected against IR-induced lung injury. This protective effect raises the possibility of using pro-oxidants to prevent inflammatory injury.

Thyroxine treatment in patients with symptoms of hypothyroidism but thyroid function tests within the reference range: randomised double blind placebo controlled crossover trial

OBJECTIVES

To determine whether thyroxine treatment is effective in patients with symptoms of hypothyroidism but with thyroid function tests within the reference range, and to investigate the effect of thyroxine treatment on psychological and physical wellbeing in healthy participants.

DESIGN

Randomised double blind placebo controlled crossover trial.

SETTING

Outpatient clinic in a general hospital.

PARTICIPANTS

25 patients with symptoms of hypothyroidism who had thyroid function tests within the reference range, and 19 controls.

METHODS

PARTICIPANTS were given thyroxine 100 microgram or placebo to take once a day for 12 weeks. Washout period was six weeks. They were then given the other to take once a day for 12 weeks. All participants were assessed physiologically and psychologically at baseline and on completion of each phase.

MAIN OUTCOME MEASURES

Thyroid function tests, measures of cognitive function and of psychological and physical wellbeing.

RESULTS

22 patients and 19 healthy controls completed the study. At baseline, patients' scores on 9 out of 15 psychological measures were impaired when compared with controls. Patients showed a significantly greater response to placebo than controls in 3 out of 15 psychological measures. Healthy participants had significantly lower scores for vitality when taking thyroxine compared to placebo (mean (SD) 60 (17) v 73 (16), P<0.01). However, patients' scores from psychological tests when taking thyroxine were no different from those when taking placebo except for a poorer performance on one visual reproduction test when taking thyroxine. Serum concentrations of free thyroxine increased and those of thyroid stimulating hormone decreased in patients and controls while they were taking thyroxine, confirming compliance with treatment. Although serum concentrations of free triiodothyronine increased in patients and controls taking thyroxine, the difference between the response to placebo and to thyroxine was significant only in the controls.

CONCLUSIONS

Thyroxine was no more effective than placebo in improving cognitive function and psychological wellbeing in patients with symptoms of hypothyroidism but thyroid function tests within the reference range. Thyroxine did not improve cognitive function and psychological wellbeing in healthy participants.

Suppression of inducible nitric oxide generation by agmatine aldehyde: beneficial effects in sepsis

The induction of inducible nitric oxide synthase (iNOS) serves an important immuno-protective function in inflammatory states, but ungoverned nitric oxide (NO) generation can contribute to a number of pathologic consequences. Delineation of the mechanisms that can downregulate iNOS-generated NO in inflammation could have therapeutic relevance. Here we show that agmatine, a metabolite of arginine, inhibits iNOS mediated nitric oxide generation in cytokine stimulated cell culture preparations. This effect was not cell type specific. Increased diamine oxidase (DAO) and decreased aldehyde dehydrogenase (AldDH) activities are also representative of inflammatory settings. Increasing the conversion of agmatine to an aldehyde form by addition of purified DAO or suppression of aldehyde breakdown by inhibition of AldDH activity increases the inhibitory effects of agmatine in an additive fashion. Inhibitors of DAO, but not monoamine oxidase (MAO), decreased the inhibitory effects of agmatine, as did the addition of AldDH or reacting aldehydes with phenylhydrazine. We examined rats given lipopolysaccharide (LPS) to evaluate the potential effects of agmatine in vivo. Endotoxic rats administered agmatine prevented the decreases in blood pressure and renal function normally associated with sepsis. Agmatine treatment also increased the survival of LPS treated mice. Our data demonstrate the capacity of agmatine aldehyde to suppress iNOS mediated NO generation, and indicate a protective function of agmatine in a model of endotoxic shock. How agmatine may aid in coordinating the early NO phase and the later repair phase responses in models of inflammation is discussed.

Effect of intravenous taurine on endotoxin-induced acute lung injury in sheep

OBJECTIVE

To find out if pretreatment with taurine would reduce the severity of endotoxin-induced acute lung injury in a large animal model.

DESIGN

Randomised controlled study under licence from the Department of Health.

SETTING

Department of Surgical Research, Ireland.

ANIMALS

15 male Suffolk sheep.

INTERVENTIONS

Vascular catheters were placed in the femoral artery and vein and a Swan-Ganz catheter in the external jugular vein under general anaesthetic. Animals were randomized into three groups: control with measurements taken at baseline and half hourly up to 90 minutes; endotoxin, given Escherichia coli endotoxin intravenously after baseline measurements and taurine given 300 mg/kg 1 hour before endotoxin was given.

MAIN OUTCOME MEASURES

Mean systemic arterial pressure, mean pulmonary arterial pressure, arterial oxygen tension (PO2), pulmonary myeloperoxidase activity, and neutrophil respiratory burst activity.

RESULTS

Endotoxin induced a severe lung injury characterised by a decrease in mean systemic blood pressure and an increase in pulmonary artery pressure, hypoxia, and an increase in pulmonary myeloperoxidase activity. Pretreatment with intravenous taurine significantly reduced these haemodynamic changes. It reduced pulmonary myeloperoxidase activity and peripheral neutropenia and increased neutrophil respiratory burst activity.

CONCLUSIONS

This data suggest that taurine may have a therapeutic role in preventing the lung injury seen in endotoxaemia.

Salicylic acid in the serum of subjects not taking aspirin. Comparison of salicylic acid concentrations in the serum of vegetarians, non-vegetarians, and patients taking low dose aspirin

AIMS

To determine serum salicylic acid concentrations in non-vegetarians and vegetarians not taking salicylate drugs, and to compare these concentrations with those found in patients taking aspirin, 75 mg daily.

METHODS

Serum samples were obtained from vegetarians (n = 37) and non-vegetarians (n = 39) not taking salicylate drugs. Non-vegetarians and vegetarians were recruited from the community and from a Buddhist monastery, respectively, in Dumfries and Galloway, Scotland. Patients (n = 14) taking aspirin (75 mg daily) were recruited from the Dumfries diabetic clinic. Serum salicylic acid concentrations were determined using a high performance liquid chromatography method with electrochemical detection.

RESULTS

Salicylic acid was detected in every serum sample analysed. Higher serum concentrations of salicylic acid were found in vegetarians than non-vegetarians: median concentrations of 0.11 (range, 0.04-2.47) micromol/litre and 0.07 (range, 0.02-0.20) micromol/litre, respectively; the median of the difference was 0.05 micromol/litre (95% confidence interval for difference, 0.03 to 0.08; p < 0.0001). The median serum concentration of salicylic acid in patients taking aspirin (75 mg daily) was 10.03 (range, 0.23-25.40) micromol/litre, which was significantly higher than that found in non-vegetarians and vegetarians. There was overlap in serum salicylic acid concentrations between the vegetarians and patients taking aspirin.

CONCLUSIONS

Salicylic acid, a non-steroidal anti-inflammatory drug, is present in fruits and vegetables and is found in higher concentrations in vegetarians than non-vegetarians. This suggests that a diet rich in fruits and vegetables contributes to the presence of salicylic acid in vivo. There is overlap between the serum concentrations of salicylic acid in vegetarians and patients taking aspirin, 75 mg daily. These findings may explain, in part, the health promoting effects of dietary fruits and vegetables.

Taurine prevents interleukin-2-induced acute lung injury in rats

BACKGROUND

The therapeutic efficacy of interleukin-2 (IL-2) has been limited by a dose-dependent vascular leak syndrome. This may be related to neutrophil-mediated endothelial injury. Taurine has been shown to decrease this injury in vitro. This study investigates the role of taurine in preventing IL-2-induced lung injury, and the role of neutrophil-endothelial interactions in mediating this injury.

METHODS

Study 1: Sprague-Dawley rats (n = 12/groups) were randomised to controls, IL-2-treated (1 x 10(6) units), and IL-2-treated with taurine (4% solution, orally for 48 h prior to IL-2 therapy). Lung injury was measured by extravascular lung water (wet/dry weight) and bronchoalveolar lavage protein concentration. Neutrophil infiltration was evaluated by measuring myeloperoxidase activity and bronchoalveolar lavage neutrophil concentration. Study 2: Rats (n = 10/group) were randomised into the same groups as study 1. Neutrophil-endothelial interactions in mesenteric vessels were assessed by intravital microscopy at half-hourly intervals.

RESULTS

Taurine reduced IL-2-induced acute lung injury as reflected by a decrease in wet-to-dry lung weight ratio from 7.2 +/- 0.5 in the IL-2 group to 4.7 +/- 0.3 in the taurine group (p < 0.05), and a decrease in bronchoalveolar neutrophil concentration from 823 +/- 19.5 in the IL-2 group to 538 +/- 18 in the taurine group (p < 0.05). Intravital microscopy demonstrated that IL-2 increased leucocyte adhesion and migration in mesenteric vessels, and that this was significantly reduced by taurine.

CONCLUSION

These data suggest that taurine prevents IL-2-induced tissue injury in part by decreasing neutrophil-endothelial interactions.

Preoperative treatment with recombinant human growth hormone prevents ischemia reperfusion-induced diaphragmatic dysfunction

BACKGROUND

Respiratory complications continue to be a major cause of morbidity and mortality following major vascular surgery. The recent UK Small Aneurysm Trial cited preoperative respiratory function as the major predictor of outcome following elective aortic surgery.

AIM

The aim of this study was to investigate the effect of aortic clamping and revascularization on diaphragmatic muscle function in a small animal model and to evaluate the role of preoperative treatment with recombinant human growth hormone (rhGH) in preventing diaphragmatic muscle dysfunction.

METHODS

Male Sprague-Dawley rats (n = 18) were randomized into one of three groups: control (n = 6) underwent laparotomy only; IR (n = 6) had a laparotomy with infrarenal cross-clamping for 30 min followed by lower torso revascularization for 2 h; IR + rhGH (n = 6) were treated with rhGH (Genotropin 0.3 IU/kg/day) for 5 days before laparotomy and aortic cross-clamping for 30 min followed by lower torso revascularization for 2 h. Diaphragmatic muscle contractile function was assessed ex vivo using electrical field stimulation in a tissue bath.

RESULTS

Two hours of IR injury resulted in a significant impairment in diaphragmatic twitch (Control, 242.01 + 38.45 g; IR, 108.55 + 7.15 g). This impairment was prevented by pretreatment with rhGH (rhGH, 319.14 + 30.71 g; P < 0.01). Tetanic function was also significantly impaired by ischemia reperfusion injury (control, 605 + 77.63 g; IR, 228.12 + 14.38 g). Again, pretreatment with rhGH prevented this deterioration (IR + rhGH, 704.39 + 45.69 g; P < 0.05) compared with controls.

CONCLUSION

The results of this study suggest that preoperative administration of rhGH may have a role in preventing the diaphragmatic dysfunction associated with infrarenal aortic cross-clamping and revascularization.

Pravastatin Attenuates Lower Torso Ischaemia–Reperfusion-induced Lung Injury by Upregulating Constitutive Endothelial Nitric Oxide Synthase

OBJECTIVES

to elicit whether pre-treatment with pravastatin will prevent or ameliorate the acute lung injury that occurs following lower torso ischaemia-reperfusion (IR) in an experimental animal model.

MATERIALS AND METHODS

male Sprague-Dawley rats were randomised into three groups (n=7/group). The control group underwent a sham laparotomy and aortic dissection. The second group underwent infrarenal aortic cross clamping for 30 min followed by reperfusion for 120 min. The third group pre-treated with pravastatin sodium (0.4 mg/kg/day over 5 days) were again subjected to an ischaemia-reperfusion (IR) injury. The parameters used to assess lung injury included: Wet to dry lung weight ratio (W:D), myeloperoxidase activity (MPO), protein concentration (BALprot) and neutrophil count (BAL PMN) of bronchoaveolar lavage fluid. Western blotting was used to determine the expression of constitutive endothelial nitric oxide synthase (ecNOS) within lung tissue.

RESULTS

IR causes an acute lung injury as indicated by statistically significant differences in W:D lung weight ratios, MPO activity, neutrophil count and BALprotein concentration in the IR group over that of controls. Pre-treatment with pravastatin attenuated this neutrophil infiltration and microvascular leakage. The pravastatin group showed a marked increased expression of ecNOS over that of the IR group and controls.

CONCLUSION

this data indicates that pre-treatment with pravastatin protects against ischaemia-reperfusion induced lung injury in an experimental animal model. We believe that its mechanism of action involves an upregulation of ecNOS, which increases basal expression of nitric oxide providing protective effects on the pulmonary circulation against microvascular injury.

Carotid Stump Syndrome: Outcome from Surgical Management

OBJECTIVES

in patients with occluded internal carotid arteries the carotid stump is a potential source of microemboli resulting in the persistence of retinal or cerebral ischaemic symptoms. We report 25 patients who had persistent cerebral and retinal ischaemic symptoms with an occluded ipsilateral ICA and a carotid stump who underwent surgical exclusion of the stump.

METHODS

between January 1988 and January 1998, 332 patients underwent carotid endarterectomy. Twenty-five patients (20 males: five females; mean age 58.9 (range 44-78 years)) had carotid stump exclusion. Indications for surgery were transient ischaemic attack (22), amaurosis fugax (eight) and cerebrovascular accident (13). Three patients had undergone contralateral carotid endarterectomy and 12 had significant contralateral stenosis. Twenty patients were being treated with aspirin and four with warfarin at the time of presentation.

RESULTS

the diagnosis of carotid stump was made in 22 patients by angiography. In the remaining three patients duplex alone was diagnostic in two patients. In the third case duplex was combined with magnetic resonance angiography (MRA) to confirm the diagnosis. Stump exclusion was carried out by oversewing the ICA origin. All but one patient remained symptom free at follow-up.

CONCLUSION

carotid stump syndrome should be considered as a likely clinical entity in patients with an occluded ICA and persisting cerebral and retinal microembolic symptoms. Surgical exclusion of the carotid stump is a safe and effective method of treatment.

Taurine attenuates LPS-induced rolling and adhesion in rat microcirculation

BACKGROUND

Adhesion of polymorphonuclear leukocytes (PMN) to endothelial cells and subsequent transendothelial migration are an early key events in the inflammatory response and play an important part in the pathogenesis of septic shock, contributing to vascular and tissue injury. Taurine (2-aminoethanesulfonic acid) is a sulphur-containing beta amino acid. It is a known antioxidant, possesses antimicrobial properties, and has previously been shown to be protective to the endothelium both in vivo and in vitro. The aim of this study was to determine if pretreatment with taurinewould attenuate the lipopolysaccharide (LPS)-induced increase in leukocyte-endothelial interactions and microvascular permeability during endotoxemia.

MATERIALS AND METHODS

Male Sprague-Dawley rats (300-350 g) were randomized into three groups: (1) Control, (2) LPS, and (3) LPS + Taurine groups. Taurine was administered orally as a 4% solution. Endotoxemia was induced using Escherichia Coli endotoxin (Serotype 0.55 B5)-15 mg/kg via a slow intravenous infusion. Using mesenteric postcapillary venules (28-32-microm diameter) the number of adherent and migrated leukocytes and their rolling velocity were measured by intravital microscopy at baseline and subsequently at 10, 30, 60, and 90 min post administration of LPS.

RESULTS

Following administration of LPS there was a reduction in leukocyte rolling velocity at 30, 60 and 90 min. This was accompanied by a significant increase in the number of adherent leukocytes at 10, 30, 60 and 90 min. Transendothelial migration was significantly increased at 90 min. Taurine significantly attenuated the LPS-induced reduction in leukocyte rolling velocity at 10 and 30 min and the number of adherent leukocytes at all time points. Taurine also attenuated the LPS-induced increase in transendothelial migration at 90 min.

CONCLUSIONS

These results demonstrate that taurine ameliorates endotoxin-induced leukocyte-endothelial cell interactions associated with sepsis, thereby suggesting that taurine may have a therapeutic role in the preventionof endothelial damage in sepsis.

The role of apoptotic cell death in cardiovascular disease

BACKGROUND

Programmed cell death, or apoptosis, is a distinct, managed form of cell death. It is fundamentally different from necrosis. It is a genetically controlled, energy-dependent method of cellular deletion without inflammation. In the cardiovascular system, apoptosis occurs as a primary and secondary event in disease pathogenesis. This review addresses our current understanding of the initiation, propagation and significance of apoptosis in the cardiovascular system, as well as assessing therapeutic potentials arising therefrom.

METHODS

A Medline search was performed and relevant publications reviewed. Further articles were obtained from the references of these publications.

RESULTS

and conclusions Apoptotic cell death is a key element in the pathogenesis and progression of ischaemia-reperfusion (IR) injury, cardiac failure, myocardial infarction, atherosclerosis, endothelial dysfunction and the clinical syndromes which these situations produce. Our increased understanding of the role of apoptosis in the pathogenesis of cardiovascular disease offers potential to develop new therapeutic strategies.

Absence of functional inducible NO synthase enhances the efficacy of tolerance induced by high dose antigen feeding

Recent studies have suggested that IL-12 and IFN-gamma may impair the ability of fed Ag to induce systemic tolerance. Because both of these cytokines can function to directly or indirectly induce inducible NO synthase (iNOS) expression, we have investigated whether the functional expression of iNOS regulates oral tolerance. C57BL/6J wild-type or C57BL/6J NOS2(-/-) mice were gavaged with a single dose of 20 mg of keyhole limpet hemocyanin (KLH), followed by s.c. immunization with KLH/CFA. In the absence of feeding Ag, several parameters of the immune response were more robust in C57BL/6J NOS2(-/-) mice following KLH/CFA immunization, including the magnitude of the delayed-type hypersensitivity response, the proliferative response, and the production of IFN-gamma and IL-2 by Ag-activated draining lymph node cells. These heightened responses in the C57BL/6J NOS2(-/-) mice are still effectively inhibited by feeding KLH. Feeding KLH to the C57BL/6J NOS2(-/-) mice elicited heightened TGF-ss1 production by Ag-activated lymphocytes, as well as augmented total IgG, IgG1, and IgG2a responses to KLH/CFA compared with that seen in Ag-fed wild-type mice. Feeding Ag to the NOS2(-/-) mice suppressed proliferative responses and IFN-gamma production, while increasing IL-4 production and the IgG1/IgG2a ratio even following a booster immunization of KLH/CFA. Administrating L-N:(6)-(1-iminoethyl)-lysine. 2HCl to wild-type mice during the period of Ag feeding reproduced the high TGF-ss1 production seen in Ag-activated lymphocytes from Ag-fed NOS2(-/-) mice. Feeding KLH is followed by transient up-regulation of NOS2 mRNA expression in the Peyer's patches of wild-type mice. Selective inhibition of NOS2 may be a simple way to augment tolerogenic mucosal immune responses.

The long term health consequences of polycystic ovary syndrome

Women with polycystic ovary syndrome have both insulin resistance and beta cell dysfunction. Consequently, they are at increased risk of developing diabetes and cardiovascular disease. Women with polycystic ovary syndrome present to clinicians at a young age and as such offer a unique opportunity to identify insulin resistant patients at an early stage. This enables the modification of risk factors and diagnosis of diabetes before the onset of macro- and micro-vascular symptoms. Increased emphasis should thus be placed on long term risk management and diabetic screening with advice on smoking, exercise and, if appropriate, weight loss. Where possible drugs that exacerbate insulin resistance should be avoided and consideration should be given to the use of insulin sensitising agents, particularly in the obese.

Kinetic analysis of a tod-lux bacterial reporter for toluene degradation and trichloroethylene cometabolism

Kinetics of toluene and trichloroethylene (TCE) degradation and bioluminescence from the bioreporter Pseudomonas putida B2 and TVA8 were investigated utilizing batch and continuous culture, respectively. Degradation was modeled using a Michaelis-Menten expression for the competition of two substrates for a single enzyme system, and bioluminescence was modeled assuming a luciferase enzyme saturational dependence on toluene as the inducer and growth substrate. During the batch experiments, bioluminescence increased at approximately 90 namp/min for initial toluene concentrations of 10 to 50 mg/L, but more slowly at higher toluene concentrations, suggesting maximum promoter induction at below 10 mg/L and toxic effects above 50 mg/L toluene. TCE degradation did not occur until toluene depletion, presumably due to competition between toluene and TCE for the toluene dioxygenase enzyme. During continuous culture, bioluminescence transiently increased, then gradually decreased in response to increasing step changes in toluene feed concentration. Bioluminescence in the CSTR appeared to be limited by growth substrate and/or inducer.

Taurine protects against early and late skeletal muscle dysfunction secondary to ischaemia reperfusion injury

OBJECTIVE

To assess the efficacy of the cytoprotective B-amino acid taurine in prevention of skeletal muscle dysfunction secondary to ischaemia-reperfusion (IR) injury.

DESIGN

Randomised controlled animal study.

SETTING

Biomedical research laboratory, teaching hospital, Republic of Ireland.

ANIMALS

96 Sprague Dawley rats.

INTERVENTIONS

Rats were randomised into three groups (n = 24/group): control (sham); ischaemia-reperfusion (untreated); and ischaemia-reperfusion + taurine. A further 24 rats were given taurine alone. The rat cremaster skeletal muscle model of four hours of ischaemia followed by reperfusion was used. Taurine 4%wt/vol was given in the animals' water throughout the experiment, beginning 48 hours before the ischaemia was initiated.

OUTCOME MEASURES

8 rats were killed from each group and muscle contractile function was assessed using electrical field stimulation in a tissue bath at 24 hrs, 48 hrs and 7 days.

RESULTS

Ischaemia followed by 24 hours, 48 hours or 7 days of reperfusion resulted in significant reduction in both muscle twitch and tetanic contractile function (p < 0.05). This was reversed by taurine, which resulted in significant preservation of twitch and tetanic contractility at all time points including one week of reperfusion (p < 0.05). There was no difference in muscle function between muscle treated with taurine after ischaemia-reperfusion and control muscle, with the same operation but without ischaemia, from 48 hours onwards.

CONCLUSIONS

These data show that pharmaceutical use of the endogenous amino acid taurine, unlike many-other agents, protects electrophysiological function in skeletal muscle against both early and late ischaemia-reperfusion injury.

Diaphragmatic dysfunction secondary to experimental lower torso ischaemia-reperfusion injury is attenuated by thermal preconditioning

BACKGROUND

Preconditioning describes the process whereby tissue exposure to a subcritical stress confers protection from subsequent injuries. This study assessed diaphragmatic muscle function after lower torso ischaemia-reperfusion (IR) and the role of thermal preconditioning in attenuation of this injury.

METHODS

Sprague-Dawley rats were randomized into three groups (24 per group): a control group, an IR group that had aortic cross-clamping for 1 h followed by reperfusion, and a third group that received thermal preconditioning 18 h before IR. Diaphragmatic function was assessed at 24 h, 48 h and 7 days.

RESULTS

IR resulted in significant diaphragmatic twitch and tetanic dysfunction compared with control muscle. Thermal preconditioning significantly attenuated this injury (P < 0.05). Mean(s.e.m.) muscle twitch and tetanic forces in the IR group were 204.9(17.2) and 282.7(19.2) g respectively at 24 h. Corresponding twitch and tetanic forces in preconditioned muscle were 270.4(25.1) and 552.0(35.2) g.

CONCLUSION

This study demonstrated that systemic IR injury produced a respiratory muscle mechanical dysfunction that was attenuated by thermal preconditioning, at 24 h, 48 h and 7 days. Preconditioning may have a role in clinical practice, particularly before elective surgery.