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Biomedical subjects

P C Sharpe

Publications and source records attributed to P C Sharpe.

At least 19 recordsLinked to original sources
PubMed2005

Two cases of inflammatory muscle disease presenting with raised serum concentrations of troponin T.

Troponins T and I are highly sensitive markers of myocardial injury. However, non-cardiac disorders, such as pulmonary embolism, renal failure, subarachnoid haemorrhage, sepsis, eclampsia, chemotherapy, and inflammatory muscle conditions (dermatomyositis and polymyositis), can also result in raised serum troponin concentrations. This article describes two cases that occurred within a month of each other in Craigavon Area Hospital, whereby conditions unrelated to myocardial ischaemia resulted in raised concentrations of cardiac markers. The first patient, in retrospect, underwent unnecessary investigation as an inpatient in the cardiac ward. Experience gained from this case led to more appropriate consultation and management of the second patient.

Adult↗
PubMed2004

Hepatoerythropoietic porphyria: a missense mutation in the UROD gene is associated with mild disease and an unusual porphyrin excretion pattern.

Hepatoerythropoietic porphyria (HEP) is an uncommon inherited cutaneous porphyria, related to porphyria cutanea tarda, that results from severe uroporphyrinogen decarboxylase (UROD) deficiency. It is characterized clinically by the onset in early childhood of severe lesions on sun-exposed skin. We describe a man aged 38 years with an unusually mild form of the disease that started in his early teens. Our data confirm that homozygosity for the F46L mutation in the UROD gene causes a mild form of HEP and show that this genotype may be associated with a unique urinary porphyrin excretion pattern in which pentacarboxylic porphyrin predominates.

Adult↗
PubMed2001

Biochemical detection and monitoring of alcohol abuse and abstinence.

The merits and limitations of traditional and new markers for alcohol abuse (and abstinence) are critically examined for detection and monitoring of alcoholics, hazardous drinkers and binge drinkers. The traditional markers discussed include gamma-glutamyltransferase (GGT), aspartate and alanine aminotransaminases (AST, ALT) and mean corpuscular volume (MCV); new markers include mitochondrial AST, carbohydrate-deficient transferrin (CDT), serum/urine 5-hydroxytryptophol, beta-hexosaminidase and acetaldehyde adducts. The strengths and weaknesses of several of the self-reporting screening questionnaires are also explored. No laboratory test is reliable enough on its own to support a diagnosis of alcoholism. Sensitivities and specificities vary considerably and depend on the population concerned. GGT continues to remain the test that combines greatest convenience and sensitivity: its diagnostic accuracy can be enhanced by combination with other traditional markers (AST, ALT, MCV). None of the newer markers offers significant advantage, although CDT seems to be better at monitoring patients for increased alcohol consumption or progress towards abstinence.

Acetaldehyde↗
PubMed2000

C-substituted macrocycles as candidates for radioimmunotherapy.

The reaction between aryl aldehydes, the macrocyclic ligand 6-methyl-1,4,8,11-tetraazacyclotetradecane-6-amine (L1), and NaBH3CN produces the corresponding benzyl-substituted ligands in good yield. Copper(II) complexes of the ligands derived from salicylaldehyde (L2), p-hydroxybenzaldehyde (L4), and p-carboxybenzaldehyde (L5) were structurally characterized: [CuL2](ClO4)2.3H2O (monoclinic, P2(1)/c, a = 11.915(6) A, b = 13.861(2) A, c = 17.065(8) A, beta = 102.14(2) degrees, Z = 4); [CuL4](ClO4)2 (monoclinic, P2(1)/n, a = 9.550(3) A, b = 17.977(2) A, c = 14.612(4) A, beta 96.76(1) degrees, Z = 4), and [CuL4](ClO4)2 (monoclinic, P2(1)/n, a = 9.286(2) A, b = 11.294(1) A, c = 23.609(8) A, beta 93.68(1) degrees, Z = 4). Conjugation of several CuII complexes to a protein (bovine serum albumin) has been pursued with a view to the application of these macrocycles as bifunctional chelating agents in radioimmunotherapy.

Crystallography, X-Ray↗
PubMed2000

Structurally reinforced tetraazamacrocyclic complexes.

The reaction between alkyl or aryl aldehydes and macrocyclic ligands with pendant amine groups produced imidazolidine-containing bi- or tricyclic ligands. The copper complexes of three of these ligands were structurally characterized: [CuL3Cl].3H2O (triclinic, P1, a = 10.041(2) A, b = 10.172(1) A, c = 11.202(1) A, alpha = 92.07(1) degrees, beta = 96.76(2) degrees, gamma = 92.99(1) degrees, Z = 2), [Cu(H2L4)Cl]Cl.2H2O (monoclinic, P2(1)/n, a = 15.159(5) A, b = 10.645(1) A, c = 19.094(6) A, beta = 93.78(1) degrees, Z = 4), [CuL5].2H2O.NaNO3 (monoclinic, P2(1)/n, a = 10.649(8) A, b = 7.261(2) A, c = 15.25(1) A, beta = 94.77(4) degrees, Z = 2). The conformational rigidity and stereochemical activity of these macrocycles and their complexes are discussed in comparison with close analogues.

Journal Article↗
PubMed2000

Serum mitochondrial aspartate transaminase activity after isoflurane or halothane anaesthesia.

We examined the effect of halothane or isoflurane anaesthesia on hepatic function in 30 ASA I-III patients aged 18-70 yr undergoing lumbar discectomy. Hepatic function was assessed before anaesthesia, at the end of surgery, and at 3, 6, 24 and 48 h after surgery using routine enzyme tests of hepatic function and mitochondrial aspartate transaminase (mAST) activity. Although serum mAST activities increased after surgery in both groups of patients, these increases were statistically significantly greater in the group that received halothane. The groups were similar with regard to other tests of hepatic function. Calculation of the ratio of serum enzyme activities compared to baseline values suggested that mAST is a sensitive marker of anaesthetic-induced hepatic injury.

Adolescent↗
PubMed1998

The effects of glucose-induced oxidative stress on growth and extracellular matrix gene expression of vascular smooth muscle cells.

Vascular smooth muscle cell (VSMC) dysfunction plays a role in diabetic macrovasculopathy and this may include abnormalities in growth characteristics and the extracellular matrix. As the actual mechanisms by which glucose induces VSMC dysfunction remain unclear, the aim of this study was to assess the potential role of glucose-induced oxidative stress. Porcine aortic VSMCs were cultured for 10 days in either 5 mmol/l normal glucose or 25 mmol/l D-glucose (high glucose). There was evidence of oxidative stress as indicated by a 50% increase in intracellular malondialdehyde (p < 0.05), increased mRNA expression of CuZn superoxide dismutase and Mn superoxide dismutase (by 51% and 37% respectively, p < 0.01) and a 50% decrease in glutathione in 25 mmol/l D-glucose (p < 0.001). Growth was increased by 25.0% (p < 0.01). mRNA expression of extracellular matrix proteins (collagens I, III, IV and fibronectin) was not altered by high glucose in these experimental conditions. Repletion of glutathione with N-acetyl L-cysteine (1 mmol/l) in VSMC grown in high glucose was associated with reduction in malondialdehyde and restored growth to that of normal glucose. The water soluble analogue of vitamin E, Trolox (200 mumol/l), reduced malondialdehyde concentrations, but had no effect on glutathione depletion or the increased growth rate seen with high glucose. The addition of buthionine sulphoximine (10 mumol/l) to VSMC cultured in normal glucose reduced glutathione, increased malondialdehyde and increased growth to a similar extent as that found in high glucose alone. These results suggest that thiol status, rather than lipid peroxides, is a key factor in modulating VSMC growth and that mRNA expression of extracellular matrix proteins is not increased in VSMC under conditions of glucose-induced oxidative stress.

Animals↗
PubMed1998

Glucose-induced oxidative stress in vascular contractile cells: comparison of aortic smooth muscle cells and retinal pericytes.

Free radical-mediated damage to vascular cells may be involved in the pathogenesis of diabetic vasculopathy. The aim of this study was to compare the extent of glucose-induced oxidative stress in both vascular smooth muscle cells (VSMCs) and pericytes and the effect on antioxidant enzyme gene expression and activities. Porcine aortic VSMC and retinal pericytes were cultured in either 5 or 25 mmol/l glucose for 10 days. Intracellular malondialdehyde (MDA) was measured as a marker of peroxidative damage, and mRNA expression of CuZn-SOD, MnSOD, catalase, and glutathione peroxidase (GPX) were measured by Northern analysis. Glutathione (GSH) was also measured. There was a significant increase in MDA in VSMCs in 25 mmol/l glucose (1.34 +/- 0.11 vs. 1.88 +/- 0.24 nmol/mg protein, 5 vs. 25 mmol/l D-glucose, mean +/- SE, n = 15, P < 0.01), but not in pericytes (0.38 +/- 0.05 vs. 0.37 +/- 0.05 nmol/mg protein, n = 11). There was a significant decrease in GSH in both cell types (VSMC, 1.40 +/- 0.13 vs. 0.69 +/- 0.12 nmol/mg protein, n = 15, P < 0.001; pericytes, 1.97 +/- 0.17 vs. 0.94 +/- 0.16 nmol/mg protein, n = 11, P < 0.001). mRNA expression of CuZnSOD and MnSOD was increased only in VSMCs (by 58.5 +/- 8.1 and 41.0 +/- 6.9%, respectively, n = 8, P < 0.01). CuZnSOD protein was increased by approximately 120% (P < 0.00001). None of the antioxidant enzyme activities was altered between 5 and 25 mmol/l glucose in either cell type. Both MnSOD activities and GSH concentrations were higher in pericytes compared with VSMC under basal (5 mmol/l) conditions (P < 0.05 and P < 0.02, respectively). These results demonstrate glucose-induced reduction of GSH in both cells, but only in VSMC is there evidence of oxidant damage in the form of lipid peroxidation, implying significant differences in intracellular responses to glucose between contractile cells in the macro- and microvasculature.

Animals↗
PubMed1997

Parkinson's disease: prospects for improved drug therapy.

L-Dopa has long been the mainstay of therapy for Parkinson's disease but its long-term shortcomings, principally uncoordinated, spasmodic or irregular movements (dyskinesias) and fluctuating control of motor symptoms (on/off fluctuations), are well documented. The postulated neuroprotective properties of L-deprenyl, often used as an adjunct to L-dopa, are under scrutiny and doubts have also been raised regarding its safety. Alternative therapeutic approaches are clearly needed. In this review, Jim Hagan, Derek Middlemiss, Paul Sharpe and George Poste outline some new approaches to treatment, with an emphasis on novel, selective dopamine receptor agonists. In addition, Parkinson's disease is commonly thought to be caused by the neurotoxic effects of an unidentified agent but recent data indicate a greater genetic component than previously recognized. Developments in the genetics of Parkinson's disease may provide the key to the next generation of therapeutics.

Animals↗
PubMed1996

The International Spinal Research Trust's strategic approach to the development of treatments for the repair of spinal cord injury.

The International Spinal Research Trust (ISRT) has selected a sub-set of the key molecular and cellular events underlying spinal injury and nerve regeneration, to be focus of their funding and other means of research support. These priority targets are (i) to understand and to minimise the damage caused by spinal injury and the resulting inflammatory and fibrotic events, in order to prevent the establishment of a post-acute situation that is ill-placed for regeneration; and (ii) to understand and then to manipulate the integrated environment for regrowth that is created by the interplay of soluble and matrix- or membrane-associated factors, both trophic and inhibitory. Investigation and, ultimately, exploitation of these targets requires the development of standardised and representative animal models and the application of quantitative methods for assessing functional re-innervation. The ISRT will also sponsor the networking of different disciplines and technologies to apply the most productive skills to spinal repair.

Humans↗
PubMed1996

Biochemical markers of alcohol abuse.

Excessive alcohol consumption is a major health problem in the UK leading to both serious morbidity and mortality. This study compared newer potential biochemical markers of excessive alcohol consumption [carbohydrate-deficient transferrin (CDT), mitochondrial AST (mAST) and alpha glutathione-s-transferase (alpha-GST)] with conventional markers (AST, ALT, GGT, MCV). Patients (n = 85) were enrolled in the study and subdivided into several groups on the basis of alcohol consumption. Patients with non-alcoholic liver disease (NALD) (n = 40) were also enrolled. All the markers, with the exception of the ratio mAST/total AST were significantly higher in heavy drinkers/alcoholics compared to teetotallers/social drinkers (p < 0.05). mAST and AST/ALT ratio were significantly higher in alcoholics compared to NALD (p < 0.01), whereas ALT was higher in the NALD group (p < 0.05). Multivariate discriminant function analysis (Wilks method) demonstrated that the logarithmic functions of AST/ALT ratio and mAST could correctly classify 87.9% of cases into either the alcoholic or NALD groups. ROC plot analysis showed that AST, mAST and GGT were the best markers at distinguishing heavy consumption of alcohol from lesser levels and that AST/ALT ratio and mAST were the best in distinguishing alcoholics from NALD. In conclusion, none of the newer biochemical markers, with the exception of mAST, offers any major advantage over the conventional markers.

Adult↗
PubMed1996

Total radical trapping antioxidant potential (TRAP) and exercise.

The relationship between physical activity, physical fitness and total radical trapping antioxidant potential (TRAP) was examined in the Northern Ireland Health and Activity Survey. This was a cross-sectional population study (n = 1600) using a two-stage probability sample of the population. TRAP was calculated using the sum of the individual serum antioxidant concentrations (urate, protein thiols, ascorbate, alpha tocopherol and bilirubin) multiplied by their respective stoichiometric values. Physical fitness was determined by estimation of VO2max by extrapolation from submaximal oxygen uptake, and physical activity was recorded by computer-assisted interview. Mean serum TRAP concentrations were significantly higher in males (653 +/- 8.2 mumol/l, mean +/- SEM) compared to females (564 +/- 8.0 mumol/l) (p < 0.0001). Both male and female smokers had significantly lower TRAP values than non-smokers (males p < 0.0001, females p = 0.02). In females, there was a positive relationship of TRAP with age (p < 0.001) and body mass index (p < 0.001) but a negative relationship with physical fitness (p < 0.05). The known beneficial effects of exercise and activity do not appear to be directly mediated through increased antioxidant status.

Adolescent↗
PubMed1995

Diffuse plane xanthomatosis associated with a monoclonal band displaying anti-smooth muscle antibody activity.

We report a patient with diffuse planar xanthomatous lesions associated with a benign monoclonal gammopathy. This patient has a very high titre of anti-smooth muscle antibody (1:10,240), but normal liver function tests and a normal liver biopsy. The paraprotein band displays anti-smooth muscle antibody activity. There is no evidence of any other underlying disease process. The findings are consistent with a diagnosis of diffuse plane xanthomatosis, but the mechanism of xanthoma formation remains unclear.

Autoantibodies↗
PubMed1995

Effect of red wine consumption on lipoprotein (a) and other risk factors for atherosclerosis.

Epidemiological studies have pointed to the role of alcohol, and red wine in particular, in reducing the incidence of coronary heart disease. This study attempted to distinguish, in vivo, the effects of components specific to red wine and those of alcohol on lipoproteins, antioxidant status and membrane fluidity. Volunteers (n = 20) were given 200 ml of red wine per day for 10 days. Following a 6-week washout, this was repeated with white wine. Changes within treatment groups were analysed by paired t tests and repeated measures analysis of variance was used to distinguish effects of red wine components and alcohol. LDL was prepared by ultracentrifugation and all other assays were by conventional laboratory techniques. No effect with either treatment was detected on total cholesterol, triglycerides, HDL or measures of antioxidant status, including the susceptibility of LDL to oxidation. Red wine reduced LDL cholesterol (p < 0.01), and both treatments reduced LDL apo B (p < 0.01) and increased LDL chol:apo B ratio (p < 0.01), implying an increase in LDL size. Potential anti-atherogenic changes specific to red wine were reduction in lipoprotein (a) (p < 0.001) and increased membrane fluidity (p < 0.01). These results are not in keeping with the proposed role of red wine components in free-radical protection, but the reduction in lipoprotein (a) merits further investigation.

Adult↗
PubMed1995

An audit of therapeutic drug monitoring of anticonvulsants.

An audit of therapeutic drug monitoring (TDM) of anticonvulsants was performed to assess both its use and misuse in the management of patients with epilepsy. Over a four week period all samples received for phenytoin, carbamazepine, sodium valproate and phenobarbitone assays were included in the audit. The aims were to establish the source of the specimens, the reasons for the requests and to ascertain what action, if any, would be taken when the result of the assay was provided. A total of 163 separate assays were performed over the four week period (43 phenytoin, 74 carbamazepine, 41 valproate, 5 phenobarbitone). Only 18.7% of all requests originated from the adult neurology department. The vast majority of tests had been ordered by junior medical staff (only 10% by consultants) and approximately 50% were 'routine' with no satisfactory clinical reason for the request offered. There was a tendency to manipulate prescribed doses on the basis of drug levels alone without taking the clinical picture into consideration. These results demonstrate a general ignorance, especially amongst junior medical staff, of the value of TDM of anticonvulsants, and reinforce the need for both an educative and interpretive service to be provided by the Chemical Pathology Department.

Adult↗