M E Callender’s research while affiliated with UK Department of Health and other places

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Publications (64)


Endothelial function, antioxidant status and vascular compliance in newly diagnosed HFE C282Y homozygotes
  • Article

March 2014

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54 Reads

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6 Citations

Advances in Medical Sciences

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Michael E Callender

This pilot study was aimed to establish techniques for assessing and observing trends in endothelial function, antioxidant status and vascular compliance in newly diagnosed HFE haemochromatosis during the first year of venesection. Untreated newly diagnosed HFE haemochromatosis patients were tested for baseline liver function, iron indices, lipid profile, markers of endothelial function, anti-oxidant status and vascular compliance. Following baseline assessment, subjects attended at 6-weeks and at 3, 6, 9 and 12-months for follow-up studies. Ten patients were recruited (M=8, F=2, mean age=51 years). Venesection significantly increased high density lipoproteins at 12-months (1.25mmol/L vs. 1.37mmol/L, p=0.01). However, venesection did not significantly affect lipid hydroperoxides, intracellular and vascular cell adhesion molecules or high sensitivity C-reactive protein (0.57μmol/L vs. 0.51μmol/L, p=0.45, 427.4ng/ml vs. 307.22ng/ml, p=0.54, 517.70ng/ml vs. 377.50ng/ml, p=0.51 and 290.75μg/dL vs. 224.26μg/dL, p=0.25). There was also no significant effect of venesection on anti-oxidant status or pulse wave velocity (9.65m/s vs. 8.74m/s, p=0.34). Venesection significantly reduced high density lipoproteins but was not associated with significant changes in endothelial function, anti-oxidant status or vascular compliance. Larger studies using this established methodology are required to clarify this relationship further.


Disordered vascular compliance in haemochromatosis

September 2013

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83 Reads

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9 Citations

Irish Journal of Medical Science

A relationship may exist between body iron stores, endothelial dysfunction and overall cardiovascular risk. To compare vascular compliance, biochemical endothelial function and antioxidant status between patients with homozygous hereditary haemochromatosis and healthy controls. Haemochromatosis patients and healthy controls were recruited. Measures of vascular compliance were assessed by applanation tonometry. Serological markers of endothelial function (plasma lipid hydroperoxides, cell adhesion molecules), antioxidant levels (ascorbate, lipid soluble antioxidants) and high-sensitivity C-reactive protein (CRP) were also measured. Thirty-five hereditary haemochromatosis patients (ten females, mean age 54.6) and 36 controls (27 female, mean age 54.0) were recruited. Haemochromatosis patients had significantly higher systolic and diastolic blood pressures. Pulse wave velocity (PWV) was significantly higher in male haemochromatosis patients (9.90 vs. 8.65 m/s, p = 0.048). Following adjustment for age and blood pressure, male haemochromatosis patients continued to have a trend for higher PWVs (+1.37 m/s, p = 0.058). Haemochromatosis patients had significantly lower levels of ascorbate (46.11 vs. 72.68 μmol/L, p = 0.011), retinol (1.17 vs. 1.81 μmol/L, p = 0.001) and g-tocopherol (2.51 vs. 3.14 μmol/L, p = 0.011). However, there was no difference in lipid hydroperoxides (0.46 vs. 0.47 nmol/L, p = 0.94), cell adhesion molecule levels (ICAM: 348.12 vs. 308.03 ng/mL, p = 0.32 and VCAM: 472.78 vs. 461.31 ng/mL, p = 0.79) or high-sensitivity CRP (225.01 vs. 207.13 mg/L, p = 0.32). Haemochromatosis is associated with higher PWVs in males and diminished antioxidants across the sexes but no evidence of endothelial dysfunction or increased lipid peroxidation.


Randomized controlled trial assessing the effect of simvastatin in primary biliary cirrhosis

May 2013

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148 Reads

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56 Citations

Liver international: official journal of the International Association for the Study of the Liver

Background: This study evaluated the effect of statins in Primary biliary cirrhosis (PBC) on endothelial function, anti-oxidant status and vascular compliance. Methods: Primary biliary cirrhosis patients with hypercholesterolaemia were randomized to receive 20 mg simvastatin or placebo in a single blind, randomized controlled trial. Body mass index, blood pressure, glucose, liver function, lipid profile, immunoglobulin levels, serological markers of endothelial function and anti-oxidant status were measured as well as vascular compliance, calculated from pulse wave analysis and velocity, at recruitment and again at 3, 6, 9 and 12 months. Results: Twenty-one PBC patients (F = 20, mean age = 55) were randomized to simvastatin 20 mg (n = 11) or matched placebo (n = 10). At completion of the trial, serum cholesterol levels in the simvastatin group were significantly lower compared with the placebo group (4.91 mmol/L vs. 6.15 mmol/L, P = 0.01). Low-density lipoprotein (LDL) levels after 12 months were also significantly lower in the simvastatin group (2.33 mmol/L vs. 3.53 mmol/L, P = 0.01). After 12 months of treatment, lipid hydroperoxides were lower (0.49 μmol/L vs. 0.59 μmol/L, P = 0.10) while vitamin C levels were higher (80.54 μmol/L vs. 77.40 μmol/L, P = 0.95) in the simvastatin group. Pulse wave velocity remained similar between treatment groups at 12 months (8.45 m/s vs. 8.80 m/s, P = 0.66). Only one patient discontinued medication owing to side effects. No deterioration in liver transaminases was noted in the simvastatin group. Conclusions: Statin therapy in patients with PBC appears safe and effective towards overall reductions in total cholesterol and LDL levels. Our initial study suggests that simvastatin may also confer advantageous effects on endothelial function and antioxidant status.


Figure 1:Time to diagnosis of AIH / PSC 'overlap' (n=12) out of the total population with initial diagnosis of 'pure' AIH (n=118). Range of time to follow up: 2 – 26 years  
Fig 1. Time to diagnosis of AIH / PSC 'overlap' syndrome in patients with AIH. n-118  
Evaluating distinctive features for early diagnosis of primary sclerosing cholangitis overlap syndrome in adults with autoimmune hepatitis
  • Article
  • Full-text available

January 2011

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48 Reads

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16 Citations

The Ulster medical journal

Overlap syndromes constitute a significant proportion of autoimmune liver disease. Our aim was to describe our cohort and evaluate practical methods of correctly diagnosing autoimmune hepatitis/primary sclerosing cholangitis overlap syndrome as early as possible clinically. 118 autoimmune hepatitis patients were screened for cholestatic liver function tests. 24 patients with cholestatic liver function tests were investigated for possible primary sclerosing cholangitis by clinicopathological review and magnetic resonance cholangiography. Retrospectively, potential predictors of autoimmune hepatitis/primary sclerosing cholangitis overlap syndrome were compared with a control group. Overlap syndrome was diagnosed in twelve (50%) of 24 autoimmune hepatitis patients with recent cholestasis. The cholestatic group had a lower AST (p=0.012) and International Autoimmune Hepatitis Group (IAHG) score (p=0.102), and higher IgM (p=0.002) at disease presentation. More patients in the cholestatic group developed ulcerative colitis (p=0.138). Identifying AIH / PSC overlap syndrome at diagnosis is often difficult. Certain clinical and biochemical features should alert the clinician. All patients with AIH, and biochemical cholestasis should be investigated with MRC.

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Primary biliary cirrhosis is associated with oxidative stress and endothelial dysfunction but not increased cardiovascular risk

November 2010

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66 Reads

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29 Citations

Hepatology Research

Aim: Primary biliary cirrhosis (PBC) is a chronic cholestatic disease which is associated with hypercholesterolaemia. Further, cholestatic diseases are associated with deficiencies of anti-oxidant vitamins. Despite these associations PBC is not associated with an increase in cardiovascular mortality. The aim of this study is to assess if primary biliary cirrhosis is associated with oxidative stress, endothelial dysfunction and alteration of vascular compliance which is a surrogate marker for cardiovascular risk. Methods: Fifty-one PBC patients and 34 control subjects were studied. Lipid soluble vitamins A, and E in addition to ascorbate and carotenoids were measured to assess anti-oxidant status. C-reactive protein, hydroperoxides and adhesion molecules sICAM-l/sVCAM-l were assessed as serological measures of endothelial function. Finally, measures of vascular compliance were assessed by applanation tonometer. Results: CRP, sICAM and sVCAM were all significantly higher in PBC patients (469.14 vs 207.13, P < 0.001; 768.12 vs 308.03,P < 0.001; 708.40 vs 461.31, P < 0.001) whilst anti-oxidant vitamin levels were lower in PBC patients, with ascorbate, vitamin E and vitamin A all significantly lower in PBC patients (39.91 vs 72.68, P < 0.001; 2.63 vs 3.14, P = 0.02; 1.08 vs 1.81, P < 0.001). Despite these findings PBC patients have a lower pulse wave velocity than control subjects (8.22 m/s vs 8.78 m/s, P = 0.022). Conclusion: PBC patients appear to have reduced vascular risk as assessed by pulse wave velocity but concurrently have evidence of endothelial dysfunction, inflammation and anti-oxidant deficiency.


Hepatic encephalopathy as an unusual late complication of transjugular intrahepatic portosystemic shunt insertion for non-cirrhotic portal hypertension caused by nodular regenerative hyperplasia in an HIV-positive patient on highly active antiretroviral therapy

January 2010

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55 Reads

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16 Citations

International Journal of STD & AIDS

Transjugular intrahepatic portosystemic shunt (TIPS) is an artificially created conduit between the portal and systemic vascular system in the liver performed percutaneously via radiological guidance. It is used mainly in conditions causing portal hypertension and its resulting complications. It reduces portal pressure by diverting portal blood flow into the systemic circulation. Hepatic encephalopathy is the most common complication following TIPS insertion and tends to present fairly early. We describe a case of hepatic encephalopathy as an unusual late complication of TIPS insertion (first presenting six years after) for non-cirrhotic portal hypertension caused by nodular regenerative hyperplasia in an HIV-positive patient on highly active antiretroviral therapy.



Current concepts in the assessment and treatment of Hepatic Encephalopathy

November 2009

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98 Reads

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145 Citations

QJM: monthly journal of the Association of Physicians

Hepatic encephalopathy (HE) is defined as a metabolically induced, potentially reversible, functional disturbance of the brain that may occur in acute or chronic liver disease. Standardized nomenclature has been proposed but a standardized approach to the treatment, particularly of persistent, episodic and recurrent encephalopathy associated with liver cirrhosis has not been proposed. This review focuses on the pathogenesis and treatment of HE in patients with cirrhosis. The pathogenesis and treatment of hepatic encephalopathy in fulminant hepatic failure is quite different and is reviewed elsewhere.


Adjuvant therapy used in conjunction with combination therapy for chronic hepatitis C improves sustained virus response rates in genotype 1 patients

October 2009

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10 Reads

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10 Citations

Journal of Viral Hepatitis

Combination treatment with pegylated interferon (Peg-IFN) and ribavirin remains the gold standard in the treatment of chronic hepatitis C. This therapy is limited by many side-effects including anaemia, neutropenia and reduced quality of life. The use of adjuvant agents to reduce the frequency of dose reductions because of haematological side-effects has been proven to be effective but there are few reports of what effect the use of these adjuvant therapies is having on sustained virological response (SVR). The aim of the study was to assess the clinical impact on sustained virological response of adjuvant therapies during combination therapy with Peg-IFN and ribavirin for chronic hepatitis C. A total of 132 patients, 96 males, were included in the study. The overall SVR was 66.7%, with 50% of genotype 1/4/6 (n = 27/54) patients achieving SVR and 78.2% of genotypes 2/3. The overall SVR of the treatment naïve patients (83/121) was 68.6%. Fifty-one of these patients were genotype 1 with 49.0% (25/51) of this group achieving SVR. The genotype 2/3 group of treatment naïve patients reached an SVR of 82.9% (58/70). Adjuvant therapy was used in 57 patients (43.8%). With the use of supportive adjuvant therapy, we achieved an overall SVR of 66.7% and in treatment naïve patients 68.6%. In genotype 1 patients, SVR rates of up to 46% have been reported in previous studies without the use of erythropoietin and granulocyte colony stimulating factor. We have demonstrated the SVR for genotype 1 can be improved to 50% overall.



Citations (36)


... This study is the first within the UK and Europe and the largest regarding proportional response to assess the attitudes and experiences of trainee gastroenterologists to DGBI training and management. The data are likely to be representative, as the survey captured the views of over 20% of the 523 gastroenterology clinical training posts in the UK, 16 Across all questions in all survey sections, the UK trainee DGBI experiential picture was worse than the previously reported equivalent ...

Reference:

O57 The consequences of limited training in disorders of gut brain interaction: results from a national survey of gastroenterology trainees
Irish society of gastroenterology
  • Citing Article
  • January 1998

Irish Journal of Medical Science

... Hereditaer haemochromatosisban a lipidperoxidáció markereinek tekinthető tiobarbitursav-reaktív termékek (thiobarbituric acid reactive substances [TBARS]) emelkedett, ugyanakkor az alfa-tokoferol, aszkorbát, retinol csökkent szintjét írták le; kis esetszámú vizsgálatban a lipid-hidroperoxidok szintje nem emelkedett. A venasectio sem befolyásolta érdemben az antioxidáns-statust [37][38][39]. ...

Endothelial function, antioxidant status and vascular compliance in newly diagnosed HFE C282Y homozygotes
  • Citing Article
  • March 2014

Advances in Medical Sciences

... Tamarix ramosissima Ledeb., T. chinensis Lour., and their hybrids (Gaskin and Schaal 2002 ), commonly called saltcedars , have formed large invasions throughout many riparian areas of the western USA and northern Mexico (Robinson 1965, Ríos and Garcia 1998, Stenquist 2000). They are now declared noxious weeds in many regions of the western United States (Rice 2005). Even with their regional noxious status, saltcedars are still used as ornamental plants and can be purchased at plant nurseries in the USA and Canada. ...

Section of biological sciences

Irish Journal of Medical Science

... Thus, it is well accepted that the arterial stiffness associated with vascular wall remodeling increases blood pressure (i.e., pulsatile pressure), thus placing vulnerable tissues at risk of microvascular damage, endothelial dysfunction, thrombosis, atherosclerosis and vasospasm [115]. In this regard, increased aortic pulse wave velocity (PWV) -indicative of arterial stiffnesshas been considered as a strong and independent predictor of cardiovascular risk in patients with different vasculopathies [115][116][117][118], but also in iron overloaded patients due to β-thalassemia major [91,92,119] or HH [120]. However, the first strong clinical suggestion of the causal role of iron excess has been reported by Wood et al., demonstrating that iron chelation with deferasirox was effective in reducing arterial stiffness [121]. ...

Disordered vascular compliance in haemochromatosis
  • Citing Article
  • September 2013

Irish Journal of Medical Science

... Notably, during infection, Zn levels decrease significantly and a person's requirement for Zn may increase with the severity of the infection. Aged individuals, infants, and chronic alcoholics are particularly more susceptible to Zn deficiency, increasing their chances of acquiring lifethreatening viral infections [45][46][47][48]. As Zn is indispensable for a strong immune response, Zn deficiency (persistent hypozincemia [serum Zn < 70 μg/dL]) can considerably dampen innate as well as adaptive antiviral immunity [4,5]. ...

Zinc Absorption in Alcoholics Using Zinc65
  • Citing Article
  • February 1985

Digestion

... Reactive oxygen species (ROS) trigger oxidative stress, which induces liver diseases such as liver fibrosis, cirrhosis , viral hepatitis, hepatocellular carcinoma (HCC), and others6364656667 . CCl4 and TAA are toxins used worldwide to generate experimental liver injury [29,68,69]. ...

659 PRIMARY BILIARY CIRRHOSIS IS ASSOCIATED WITH OXIDATIVE STRESS AND ENDOTHELIAL DYSFUNCTION
  • Citing Article
  • April 2009

Journal of Hepatology

... Per Cash et al., patients with PBC were randomized to receive 20 mg simvastatin (n=11) or placebo (n=10) for 12 months. After the trial, serum cholesterol in the simvastatin group was significantly lower compared to the placebo group (4.91 mmol/L vs. 6.16 mmol/L, p = 0.01) [8]. Furthermore, Kim et al. performed a systematic review and meta-analysis showing that statin use is associated with a lower risk of hepatic decompensation and mortality and might reduce portal hypertension in chronic liver diseases [9]. ...

Randomized controlled trial assessing the effect of simvastatin in primary biliary cirrhosis
  • Citing Article
  • May 2013

Liver international: official journal of the International Association for the Study of the Liver

... In CEP, the induction of an iron deficiency was able to drastically decrease hematological and cutaneous symptoms in some patients [11][12][13] as well as in cellular and mouse models [14]. There are conflicting reports on whether or not iron supplementation is beneficial in erythropoietic protoporphyrias [6,7,[15][16][17][18][19][20][21][22][23][24][25][26]. ...

Erythropoietic protoporphyria, transfusion therapy and liver disease
  • Citing Article
  • July 2006

British Journal of Dermatology

... [61][62][63] Conversely, approximately 10% of adult patients with AIH have abnormal cholangiographic features on MRCP which are consistent with PSC. 64 However, it is important to note that the IAIHG scoring system was not designed with the purpose of diagnosing variant syndromes, hence these numbers are only rough estimates. ...

Evaluating distinctive features for early diagnosis of primary sclerosing cholangitis overlap syndrome in adults with autoimmune hepatitis

The Ulster medical journal

... 15,16 Homocysteine (Hcy) is shown to be decreased in a variety of liver diseases. 17,18 Vitamin C, also known as ascorbic acid, is a powerful antioxidant with the ability to scavenge many physiological free radicals, promote iron absorption, detoxification, etc. 19 Compared with healthy controls, serum vitamin C levels were found significantly decreased in PBC patients, 20 but did not change in AIH patients, as demonstrated in another study. 21 Vitamin D is a class of important fat-soluble ringopening sterol, which main functions include the regulation of blood calcium and phosphorus concentration, new bone formation and calcification, promotion of the growth and differentiation of skin cells, and immune function modulation. ...

Primary biliary cirrhosis is associated with oxidative stress and endothelial dysfunction but not increased cardiovascular risk
  • Citing Article
  • November 2010

Hepatology Research