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M J Davies

Publications and source records attributed to M J Davies.

At least 19 recordsLinked to original sources
PubMed2007

The impact of glycation on apolipoprotein A-I structure and its ability to activate lecithin:cholesterol acyltransferase.

AIMS/HYPOTHESIS: Hyperglycaemia, one of the main features of diabetes, results in non-enzymatic glycation of plasma proteins, including apolipoprotein A-I (apoA-I), the most abundant apolipoprotein in HDL. The aim of this study was to determine how glycation affects the structure of apoA-I and its ability to activate lecithin:cholesterol acyltransferase (LCAT), a key enzyme in reverse cholesterol transport. MATERIALS AND METHODS: Discoidal reconstituted HDL (rHDL) containing phosphatidylcholine and apoA-I ([A-I]rHDL) were prepared by the cholate dialysis method and glycated by incubation with methylglyoxal. Glycation of apoA-I was quantified as the reduction in detectable arginine, lysine and tryptophan residues. Methylglyoxal-AGE adduct formation in apoA-I was assessed by immunoblotting. (A-I)rHDL size and surface charge were determined by non-denaturing gradient gel electrophoresis and agarose gel electrophoresis, respectively. The kinetics of the LCAT reaction was investigated by incubating varying concentrations of discoidal (A-I)rHDL with a constant amount of purified enzyme. The conformation of apoA-I was assessed by surface plasmon resonance. RESULTS: Methylglyoxal-mediated modifications of the arginine, lysine and tryptophan residues in lipid-free and lipid-associated apoA-I were time- and concentration-dependent. These modifications altered the conformation of apoA-I in regions critical for LCAT activation and lipid binding. They also decreased (A-I)rHDL size and surface charge. The rate of LCAT-mediated cholesterol esterification in (A-I)rHDL varied according to the level of apoA-I glycation and progressively decreased as the extent of apoA-I glycation increased. CONCLUSIONS/INTERPRETATION: It is concluded that glycation of apoA-I may adversely affect reverse cholesterol transport in subjects with diabetes.

Apolipoprotein A-I↗
PubMed2007

U-500 insulin: why, when and how to use in clinical practice.

Some patients with type 2 diabetes mellitus (T2DM) have severe insulin resistance. Their insulin requirements are significantly greater. These patients need to take 2-3 injections at the same time to take the correct insulin dose or to redial the insulin pen. When daily insulin requirements are in excess of 300 units/day, the volume of the injected insulin becomes an issue. Large-volume injection can cause discomfort and lead to poor concordance with treatment. Using high-strength insulin e.g. U-500 insulin can reduce the volume of the injected insulin. Despite publications of small case reports or case series, no universal guidelines exist on the use of U-500 insulin. We discuss common sense approaches when considering the use of U-500 insulin in clinical practice.

Diabetes Mellitus, Type 2↗
PubMed2006

Glargine versus NPH insulin: efficacy in comparison with insulin aspart in a basal bolus regimen in type 1 diabetes--the glargine and aspart study (GLASS) a randomised cross-over study.

The aim of the study was to compare the efficacy of insulin glargine and aspart with NPH insulin and aspart in a basal bolus regimen in type 1 diabetes. In this 36-week randomised open-label two-period cross-over trial, subjects received 16 weeks' treatment with either once-daily insulin glargine or twice-daily NPH insulin after 4-week run-in. Primary outcome was HbA1c and secondary outcomes were fasting plasma glucose (FPG), weight change, incidence of hypoglycaemia, effect on lipid profile and patient satisfaction. Sixty patients with type 1 diabetes were recruited (33 male, mean age 42.7 years, mean HbA1c 8.53%) with 53 completing the study. At completion, HbA1c was lower with glargine and aspart than with NPH and aspart (8.07% versus 8.26%, difference -0.19 [95% CI 0.37-0.01]%, p=0.04). FPG was significantly different between glargine and NPH (p=0.002), with mean FPG on glargine 3mmol/L lower than on NPH at the end of the study. There were no differences in hypoglycaemia rate (p=0.63), weight (p=0.45) or lipid profile (p=0.18). Patient satisfaction was greater with glargine (DTSQ, p=0.001). Three patients discontinued as they wished to remain on glargine. We suggest that glargine combined with aspart is an effective basal bolus regimen in type 1 diabetes.

Adult↗
PubMed2006

Rskalpha-actin/hIGF-1 transgenic mice with increased IGF-I in skeletal muscle and blood: impact on regeneration, denervation and muscular dystrophy.

Human IGF-I was over-expressed in skeletal muscles of C57/BL6xCBA mice under the control of the rat skeletal alpha-actin gene promoter. RT-PCR verified expression of the transgene in skeletal muscle but not in the liver of 1- and 21-day old heterozygote transgenic mice. The concentration of endogenous mouse IGF-I, measured by an immunoassay which does not detect human IGF-I, was not significantly different between transgenic mice and wild-type littermates (9.5 +/- 0.8 and 13.3 +/- 1.9 ng/g in muscle; 158.3 +/- 18.6 and 132.9 +/- 33.1 ng/ml in plasma, respectively). In contrast, quantitation with antibodies to human IGF-I showed an increase in IGF-I of about 100 ng/ml in plasma and 150 ng/g in muscle of transgenic mice at 6 months of age. Transgenic males, compared to their age matched wild-type littermates, had a significantly higher body weight (38.6 +/- 0.53 g vs. 35.8 +/- 0.64 g at 6 months of age; P < 0.001), dry fat-free carcass mass (5.51 +/- 0.085 vs. 5.08 +/- 0.092 g; P < 0.001) and myofibrillar protein mass (1.62 +/- 0.045 vs. 1.49 +/- 0.048 g; P < 0.05), although the fractional content of fat in the carcass was lower (167 +/- 7.0 vs. 197 +/- 7.7 g/kg wet weight) in transgenic animals. There was no evidence of muscle hypertrophy and no change in the proportion of slow type I myofibres in the limb muscles of Rskalpha-actin/hIGF-I transgenic mice at 3 or 6 months of age. Phenotypic changes in Rskalpha-actin/hIGF-I mice are likely to be due to systemic as well as autocrine/paracrine effects of overproduction of IGF-I due to expression of the human IGF-I transgene. The effect of muscle specific over-expression of Rskalpha-actin/hIGF-I transgene was tested on: (i) muscle regeneration in auto-transplanted whole muscle grafts; (ii) myofibre atrophy following sciatic nerve transection; and (iii) sarolemmal damage and myofibre necrosis in dystrophic mdx muscle. No beneficial effect of muscle specific over-expression of Rskalpha-actin/hIGF-I transgene was seen in these three experimental models.

Actins↗
PubMed2006

Hydrazine compounds inhibit glycation of low-density lipoproteins and prevent the in vitro formation of model foam cells from glycolaldehyde-modified low-density lipoproteins.

AIMS/HYPOTHESIS: Previous studies have shown that glycation of LDL by methylglyoxal and glycolaldehyde, in the absence of significant oxidation, results in lipid accumulation in macrophage cells. Such 'foam cells' are a hallmark of atherosclerosis. In this study we examined whether LDL glycation by methylglyoxal or glycolaldehyde, and subsequent lipid loading of cells, can be inhibited by agents that scavenge reactive carbonyls. Such compounds may have therapeutic potential in diabetes-associated atherosclerosis. MATERIALS AND METHODS: LDL was glycated with methylglyoxal or glycolaldehyde in the absence or presence of metformin, aminoguanidine, Girard's reagents P and T, or hydralazine. LDL modification was characterised by changes in mobility (agarose gel electrophoresis), cross-linking (SDS-PAGE) and loss of amino acid residues (HPLC). Accumulation of cholesterol and cholesteryl esters in murine macrophages was assessed by HPLC. RESULTS: Inhibition of LDL glycation was detected with equimolar or greater concentrations of the scavengers over the reactive carbonyl. This inhibition was structure-dependent and accompanied by a modulation of cholesterol and cholesteryl ester accumulation. With aminoguanidine, Girard's reagent P and hydralazine, cellular sterol levels returned to control levels despite incomplete inhibition of LDL modification. CONCLUSIONS/INTERPRETATION: Inhibition of LDL glycation by interception of the reactive aldehydes that induce LDL modification prevents lipid loading and model foam cell formation in murine macrophage cells. Carbonyl-scavenging reagents, such as hydrazines, may therefore help inhibit LDL glycation in vivo and prevent diabetes-induced atherosclerosis.

Acetaldehyde↗
PubMed2006

The prevalence of co-morbid depression in adults with Type 2 diabetes: a systematic review and meta-analysis.

AIM: To conduct a systematic literature review in order to estimate the prevalence and odds ratio of clinically relevant depression in adults with Type 2 diabetes compared with those without. METHODS: MEDLINE, EMBASE and PSYCINFO databases were searched using MeSH terms and free text to identify relevant controlled studies. Published reference lists were also examined. Study selection and appraisal were conducted independently by two reviewers and a meta-analysis was performed to synthesize and analyse the data. RESULTS: Ten controlled studies including a total of 51 331 people were published between January 1980 and May 2005. The prevalence of depression was significantly higher in patients with Type 2 diabetes compared with those without [17.6 vs. 9.8%, OR = 1.6, 95%, confidence interval (CI) 1.2-2.0]. However, in most studies, patients with diabetes differed from those without on variables known to be associated with an increased risk of depression. The prevalence of depression was higher in females with diabetes (23.8%) compared with males (12.8%); however, the odds ratio for depression in patients with Type 2 diabetes compared with those without was higher in males (OR = 1.9, 95% CI 1.7-2.1) than females (OR = 1.3, 95% CI 1.2-1.4). Failure to report potential confounders prevented a more rigorous meta-analysis of risk. CONCLUSION: We identified raised rates of depression in people with Type 2 diabetes, however, there is a need for well-controlled and better-reported studies to inform the development of effective treatments for depression in these patients.

Adolescent↗
PubMed2006

Reactions of myeloperoxidase-derived oxidants with biological substrates: gaining chemical insight into human inflammatory diseases.

The heme enzyme myeloperoxidase (MPO) is released at sites of inflammation by activated leukocytes. A key function of MPO is the production of hypohalous acids (HOX, X = Cl, Br) which are strong oxidants with potent antibacterial properties. However, HOX can also damage host tissue when produced at the wrong place, time or concentration; this has been implicated in several human diseases. Thus, elevated blood and leukocyte levels of MPO are significant independent risk factors for atherosclerosis, and specific markers of HOX-mediated protein oxidation are often present at elevated levels in patients with inflammatory diseases (e.g. asthma). HOX react readily with amino acids, proteins, carbohydrates, lipids, nucleobases and antioxidants. Sulfur-containing amino acids (Cys, Met, cystine) and amines on amino acids, nucleobases, sugars and lipids are the major targets for HOX. Reaction with amines generates chloramines (RNHCl) and bromamines (RNHBr), which are more selective oxidants than HOX and are key intermediates in HOX biochemistry. As these and other products of MPO-derived oxidants are unstable, understanding the role of HOX-induced damage in disease cannot be obtained solely by stable product analysis, and knowledge of the reaction kinetics is essential. This review collates kinetic and product data for HOX, chloramine and bromamine reactions with biological substrates. It highlights how kinetic data may be used to predict the effect of HOX-mediated oxidation on complex biological targets, such as lipoproteins and extracellular matrix in atherosclerosis, or protein-DNA complexes in cancer, thereby providing a basis for unraveling the mechanisms by which these oxidants generate biological damage.

Atherosclerosis↗
PubMed2005

Factors determining the optimal body site and method for obtaining punch biopsies of human skin as a tissue in which to assess pharmacodynamic and pharmacokinetic endpoints in drug development studies.

There are potential advantages to detecting pharmacodynamic (PD) and pharmacokinetic (PK) endpoints in a tissue-based compartment such as the skin during the development of molecularly targeted drugs. We explored regional differences between inner arm, inner thigh, lower back and buttocks in 12 healthy male Caucasian volunteers in the tolerability of skin biopsy procedures; the Ki67 proliferation index; the frequency of detecting hair follicles and sweat glands; and the percentage of melanocytes. We also explored the amounts of tissue and protein obtained, and two separate methods of splitting biopsies for processing in mutually exclusive media. Biopsies from all body sites were well tolerated. The subjective ranking order was inner arm > buttocks = back > thigh. There were no statistically significant differences in the Ki67 labelling index (P > 0.05). The frequency of detecting sweat glands was the same in all body sites, but the frequency of detecting hair follicles was higher in back and buttock, compared to arm and thigh. The percentage of melanocytes was significantly lower in the buttocks compared to the back and thigh (P < 0.05), but not compared to the arm (P = 0.07). A 4-mm punch biopsy yielded a mean of 16.8 mg of tissue (range: 9-28 mg) and 160 microg of protein (range: 80-270 microg). In vivo sample splitting, by following a 2-mm punch with a 4-mm overpunch, had a shorter time from devascularisation to immersion into processing medium than ex vivo dissection of a 4-mm sample, which may be of importance to the assessment of labile endpoints. We conclude that multiple punch biopsies of the skin are feasible, with the buttocks representing the studied body site with the optimal balance between tolerability, hair follicle density and melanocyte density for obtaining tissue in which to assess PD and PK endpoints during drug development studies.

Adolescent↗
PubMed2005

Glycation of low-density lipoproteins by methylglyoxal and glycolaldehyde gives rise to the in vitro formation of lipid-laden cells.

AIMS/HYPOTHESIS: Previous studies have implicated the glycoxidative modification of low-density lipoprotein (LDL) by glucose and aldehydes (apparently comprising both glycation and oxidation), as a causative factor in the elevated levels of atherosclerosis observed in diabetic patients. Such LDL modification can result in unregulated cellular accumulation of lipids. In previous studies we have characterized the formation of glycated, but nonoxidized, LDL by glucose and aldehydes; in this study we examine whether glycation of LDL, in the absence of oxidation, gives rise to lipid accumulation in arterial wall cell types. METHODS: Glycated LDLs were incubated with macrophage, smooth muscle, or endothelial cells. Lipid loading was assessed by HPLC analysis of cholesterol and individual esters. Oxidation was assessed by cholesterol ester loss and 7-ketocholesterol formation. Cell viability was assessed by lactate dehydrogenase release and cell protein levels. RESULTS: Glycation of LDL by glycolaldehyde and methylglyoxal, but not glucose (in either the presence or absence of copper ions), resulted in cholesterol and cholesterol ester accumulation in macrophage cells, but not smooth muscle or endothelial cells. The extent of lipid accumulation depends on the degree of glycation, with increasing aldehyde concentration or incubation time, giving rise to greater extents of particle modification and lipid accumulation. Modification of lysine residues appears to be a key determinant of cellular uptake. CONCLUSIONS/INTERPRETATION: These results are consistent with LDL glycation, in the absence of oxidation, being sufficient for rapid lipid accumulation by macrophage cells. Aldehyde-mediated "carbonyl-stress" may therefore facilitate the formation of lipid-laden (foam) cells in the artery wall.

Acetaldehyde↗
PubMed2005

Diabetes screening anxiety and beliefs.

AIMS: This study assesses the impact of screening for diabetes on anxiety levels in an ethnically mixed population in the UK, and explores whether beliefs about Type 2 diabetes account for these anxiety levels. METHODS: This cross-sectional study recruited individuals who were identified at high risk of developing diabetes through general practitioners' (GPs) lists or through public media recruitment. Participants completed an oral glucose tolerance test (OGTT). Between blood tests, participants completed the Spielberger State Anxiety Scale Short Form, the Emotional Stability Scale of the Big Five Inventory 44 and three scales from the Diabetes Illness Representations Questionnaire, revised for this study. RESULTS: Of the 1339 who completed the OGTT and questionnaire booklet, 54% were female, with 21% from an Asian background. Forty-five per cent of participants reported little to moderate amounts of anxiety at screening (mean 35.2; sd = 11.6). There was no significant effect of family history of diabetes, ethnic group or recruitment method on anxiety. The only variable significantly associated (negatively) with anxiety was the personality trait of emotional stability. Of responders, 64% and 61% agreed that diabetes was caused by diet or hereditary factors, respectively. Only 155 individuals (12%) agreed that diabetes was serious, shortens life and causes complications. CONCLUSIONS: The results of this study replicate that of previous studies, indicating that screening for diabetes does not induce significant anxiety. Bivariate analysis indicated that individuals who perceived diabetes to be serious, life shortening and resulting in complications had higher anxiety scores, the personality trait of emotional stability being the strongest predictor of anxiety.

Adult↗
PubMed2005

LDL-C goal attainment with the addition of ezetimibe to ongoing simvastatin treatment in coronary heart disease patients with hypercholesterolemia.

OBJECTIVE: To evaluate the addition of ezetimibe or placebo to on-going simvastatin treatment on attaining the LDL-C treatment target of </= 2.60 mmol/L (100 mg/dL) in coronary heart disease (CHD) patients with hypercholesterolemia. METHODS: Patients with documented CHD were recruited if they were on a stable dose of simvastatin 10 mg or 20 mg for at least 6 weeks, had LDL-C > 2.60 mmol/L and </= 4.20 mmol/L (> 100 mg/dL and </= 160 mg/dL), triglycerides </= 4.00 mmol/L (355 mg/dL) and hepatic transaminases and creatine kinase </= 50% above the upper limit of normal. After a 4-week placebo and diet run-in period, eligible patients were randomized to a double-blind, placebo-controlled comparative study with ezetimibe 10mg co-administered with on-going simvastatin 10mg or 20 mg (n = 208) versus placebo to match ezetimibe co-administered with simvastatin 10mg or 20mg for 6 weeks (n = 210). RESULTS: When ezetimibe was added to on-going simvastatin therapy, a significantly greater percentage of patients attained the LDL-C target of </= 2.60 mmol/L after 6 weeks of treatment compared to placebo added to on-going simvastatin (80.4% vs. 17.4%, respectively;p </= 0.001). When co-administered with on-going simvastatin therapy, mean percentage reduction in LDL-C from baseline was significantly larger in the ezetimibe group compared to placebo (27.1% vs. 4.1%, respectively; p </= 0.001). The co-administration of ezetimibe or placebo to on-going simvastatin treatment was generally well tolerated. CONCLUSIONS: Ezetimibe co-administered with on-going simvastatin 10 mg or 20 mg treatment enabled more CHD patients with hypercholesterolemia to attain the LDL-C treatment target of </= 2.60 mmol/L.

Administration, Oral↗
PubMed2004

Prevention of Type 2 diabetes mellitus. A review of the evidence and its application in a UK setting.

Abstract Type 2 Diabetes mellitus (T2DM) is a complex metabolic, multifactorial disease, which affects the quality, quantity and style of life. People with T2DM have a life expectancy that can be shortened by as much as 15 years, with up to 75% dying of macrovascular complications. To reduce the impact of T2DM in the 21st century, we need an approach that not only optimally treats the person with established diabetes but also prevents diabetes from occurring in the first place. The best evidence for prevention of diabetes is for interventions that target individuals at highest risk. Targeting patients who have impaired glucose tolerance with lifestyle changes including physical activity and dietary factors has been shown to be effective in the Chinese, North American and Finnish populations. In order for such lifestyle interventions to be successful in other populations, they need to be culturally sensitive, individualized and sustained. Some pharmacological agents including metformin and acarbose have also been shown to be effective, although the profile of those who respond is different. There continues to be a need to develop and evaluate interventions that target communities and populations at risk in a UK setting.

Diabetes Mellitus, Type 2↗
PubMed2004

A comparison of open and laparoscopic approaches to adrenalectomy in patients with phaeochromocytoma.

We compared the perioperative profiles of patients undergoing unilateral phaeochromocytoma resection performed by open adrenalectomy with those performed by laparoscopic adrenalectomy. Data was collected prospectively on 24 patients (12 open, 12 laparoscopic). All patients underwent extensive preoperative medical preparation with phenoxybenzamine and beta-blockers. The final preoperative dose of phenoxybenzamine was similar in each group (laparoscopic 119+/-60 mg/day, open 100+/-25 mg/day). Intraoperative haemodynamic instability was assessed by the requirement for therapeutic intervention. More haemodynamic instability was observed in the laparoscopic group but the differences were not statistically significant. Sodium nitroprusside use to treat hypertension (systolic blood pressure >180 mmHg) was more frequent and the duration of the infusions longer in the laparoscopic group; high dose beta-blocker therapy with atenolol and/or esmolol to treat intraoperative tachycardia (heart rate >90) was also more frequent in the laparoscopic group. The small sample size of the study limited the ability to detect a true difference. Blood loss was greater in the open adrenalectomy group but the difference was not significant. The operating time was significantly longer (236+/-78 vs 147+/-47 min, P<0.01) but the duration of postoperative hospitalization was significantly shorter (5+/-2 vs 11+/-4 days, P<0.01) in the laparoscopic group. Postoperative complications were not significantly different. There were no perioperative deaths. Overall, we observed more haemodynamic instability in patients undergoing laparoscopic resection but were unable to demonstrate a statistically significant difference. In our experience, laparoscopic adrenalectomy has the advantage of a shorter time to discharge from hospital.

Adrenal Gland Neoplasms↗
PubMed2003

Cardiological assessment of first-degree relatives in sudden arrhythmic death syndrome.

4.1% of sudden cardiac deaths in the 16-64 age-group are unexplained. In this group, cardiac pathological findings are normal and toxicological tests are negative; termed sudden arrhythmic death syndrome (SADS). We searched for evidence of inherited cardiac disease in cases of SADS. Of 147 first-degree relatives of 32 people who died of SADS, 109 (74%) underwent cardiological assessment. Seven (22%) of the 32 families were diagnosed with inherited cardiac disease: four with long QT syndrome; one with non-structural cardiac electrophysiological disease; one with myotonic dystrophy; and one with hypertrophic cardiomyopathy. Families of people who die of SADS should be offered assessment in centres with experience of inherited cardiac disease.

Adolescent↗
PubMed2003

Hypochlorite-induced oxidation of amino acids, peptides and proteins.

Activated phagocytes generate the potent oxidant hypochlorite (HOCl) via the release of the enzyme myeloperoxidase and hydrogen peroxide. HOCl is known to react with a number of biological targets including proteins, DNA, lipids and cholesterol. Proteins are likely to be major targets for reaction with HOCl within a cell due to their abundance and high reactivity with HOCl. This review summarizes information on the rate of reaction of HOCl with proteins, the nature of the intermediates formed, the mechanisms involved in protein oxidation and the products of these reactions. The predicted targets for reaction with HOCl from kinetic modeling studies and the consequences of HOCl-induced protein oxidation are also discussed.

Amino Acids↗
PubMed2003

Sudden, unexpected cardiac or unexplained death in England: a national survey.

BACKGROUND: Post-mortem examinations of adults who were apparently healthy but died suddenly and unexpectedly sometimes reveal no morphological abnormalities to explain their deaths. The frequency of such unexplained deaths in relation to other causes of sudden cardiac death is not known. AIM: To estimate the frequency of sudden unexpected cardiac or unexplained death in England. DESIGN: Prospective survey using a stratified random sample of 83 of the 132 H.M. Coroner's jurisdictions in England. METHODS: Consecutive White Caucasians, aged 16-64 years, with no medical history of cardiac disease, seen alive within 12 h of death, on whom autopsy found either a cardiac or no identifiable cause of death, were included. The coroner's officer sent a copy of the post-mortem report and a completed case registration form to the investigators, with tissue samples. RESULTS: Sixty-seven (81%) coroners participated, each maintaining prospective surveillance for 4 months. Of 692 ascertained cases, case registration forms were received for 650 (94%), post-mortem reports for 682 (99%), blood samples for 569 (82%), myocardial slices for 517 (75%) and whole hearts for 47 (7%). In cases with myocardial tissue, death was ascribed to ischaemic heart disease in 465 (82.4%). In 43.1% the ischaemia was acute, in 19.1% there was myocardial scarring but no acute ischaemia, and 20.2% had coronary atheroma only. Death was due to left ventricular hypertrophy in 32 (5.7%), to other cardiac causes in 30 (5.3%) and in 23 (4.1%) there was no clear cause. Those with cardiac causes were 81% male, median ages 55.9 (male) and 56.6 (female) years. The 23 unexplained deaths were 57% female, median ages 40.5 (male) and 54.9 (female) years. The estimated annual frequency of sudden unexpected death due to cardiac or unidentified causes, in English adults of employment age, was 11/100,000 (3481 annual deaths). DISCUSSION: In 4.1% of sudden unexpected deaths under 65 years, no cause was found. Until it becomes accepted practice to identify these cases by a name, such as Sudden Adult Death Syndrome (SADS), it will not be possible to study their aetiology systematically.

Adolescent↗