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Biomedical subjects

P H Evans

Publications and source records attributed to P H Evans.

At least 19 recordsLinked to original sources
PubMed2006

Home-based versus hospital-based rehabilitation after myocardial infarction: A randomized trial with preference arms--Cornwall Heart Attack Rehabilitation Management Study (CHARMS).

BACKGROUND: Participation in cardiac rehabilitation after acute myocardial infarction is sub-optimal. Offering home-based rehabilitation may improve uptake. We report the first randomized study of cardiac rehabilitation to include patient preference. AIM: To compare the clinical effectiveness of a home-based rehabilitation with hospital-based rehabilitation after myocardial infarction and to determine whether patient choice affects clinical outcomes. DESIGN: Pragmatic randomized controlled trial with patient preference arms. SETTING: Rural South West England. METHODS: Patients admitted with uncomplicated myocardial infarction were offered hospital-based rehabilitation classes over 8-10 weeks or a self-help package of six weeks' duration (the Heart Manual) supported by a nurse. Primary outcomes at 9 months were mean depression and anxiety scores on the Hospital Anxiety Depression scale, quality of life after myocardial infarction (MacNew) score and serum total cholesterol. RESULTS: Of the 230 patients who agreed to participate, 104 (45%) consented to randomization and 126 (55%) chose their rehabilitation programme. Nine month follow-up data were available for 84/104 (81%) randomized and 100/126 (79%) preference patients. At follow-up no difference was seen in the change in mean depression scores between the randomized home and hospital-based groups (mean difference: 0; 95% confidence interval, -1.12 to 1.12) nor mean anxiety score (-0.07; -1.42 to 1.28), mean global MacNew score (0.14; -0.35 to 0.62) and mean total cholesterol levels (-0.18; -0.62 to 0.27). Neither were there any significant differences in outcomes between the preference groups. CONCLUSIONS: Home-based cardiac rehabilitation with the Heart Manual was as effective as hospital-based rehabilitation for patients after myocardial infarction. Choosing a rehabilitation programme did not significantly affect clinical outcomes.

Chi-Square Distribution↗
PubMed2006

Home-based cardiac rehabilitation versus hospital-based rehabilitation: a cost effectiveness analysis.

BACKGROUND: Home-based cardiac rehabilitation offers an alternative to traditional, hospital-based cardiac rehabilitation. AIM: To compare the cost effectiveness of home-based cardiac rehabilitation and hospital-based cardiac rehabilitation. METHODS: 104 patients with an uncomplicated acute myocardial infarction and without major comorbidity were randomized to receive home-based rehabilitation (n=60) i.e. nurse facilitated, self-help package of 6 weeks' duration (the Heart Manual) or hospital-based rehabilitation for 8-10 weeks (n=44). Complete economic data were available in 80 patients (48 who received home-based rehabilitation and 32 who received hospital-based rehabilitation). Healthcare costs, patient costs, and quality of life (EQ-5D4.13) were assessed over the 9 months of the study. RESULTS: The cost of running the home-based rehabilitation programme was slightly lower than that of the hospital-based programme (mean (95% confidence interval) difference - 30 pounds sterling (- 45 pounds sterling to - 12 pounds sterling) [-44 euro, -67 euro to -18 euro] per patient. The cost difference was largely the result of reduced personnel costs. Over the 9 months of the study, no significant difference was seen between the two groups in overall healthcare costs (78 pounds sterling, - 1102 pounds sterling to 1191 pounds sterling [-115 euro, -1631 euro to -1763 euro] per patient) or quality adjusted life-years (-0.06 (-0.15 to 0.02)). The lack of significant difference between home-based rehabilitation and hospital-based rehabilitation did not alter when different costs and different methods of analysis were used. CONCLUSIONS: The health gain and total healthcare costs of the present hospital-based and home-based cardiac rehabilitation programmes for patients after myocardial infarction appear to be similar. These initial results require affirmation by further economic evaluations of cardiac rehabilitation in different settings.

Cost-Benefit Analysis↗
PubMed2006

Prevalence and clinical implications of the inter-arm blood pressure difference: A systematic review.

A blood pressure (BP) difference between arms was first reported over 100 years ago. Knowledge of its prevalence and relevance to the accurate measurement of BP remains poor. Current hypertension guidelines do not emphasise it. The objectives of this study were to establish the best estimate of prevalence of the inter-arm difference (IAD) in the population, to consider its implications for accurate BP measurement and treatment, and to discuss its aetiology and potential as a risk marker for cardiovascular disease. Systematic literature review was carried out. The data sources were Medline EMBASE and CINAHL databases, and Index of Theses. Studies reporting prevalence rates of IAD were retrieved and considered for inclusion against explicit methodological criteria. Point prevalence rates were extracted and weighted mean prevalence rates calculated. The main outcome measures were weighted mean prevalences of systolic IAD > or =10 and > or =20 mm Hg and of diastolic IAD > or =10 mm Hg. Thirty-one studies were identified. Most had methodological weaknesses; only four met the inclusion criteria. Pooled prevalences of the IAD from these four studies were 19.6% systolic > or =10 mm Hg (95% CI 18.0-21.3%), 4.2% systolic > or =20 mm Hg (95% CI 3.4-5.1%) and 8.1% diastolic > or =10 mm Hg (95%CI 6.9-9.2%). In conclusion, an IAD is present in a substantial number of patients and should be looked for whenever diagnosis and treatment depend on accurate measurements of BP. The importance of an IAD should be better emphasised in current hypertension management guidelines. There is evidence associating an IAD with peripheral vascular disease, raising the possibility that its presence may predict cardiovascular events.

Algorithms↗
PubMed2004

A simple pragmatic system for detecting new cases of type 2 diabetes and impaired fasting glycaemia in primary care.

BACKGROUND: Although whole population screening for type 2 diabetes is not currently considered to be justified, targeted screening within higher risk groups may be more cost-effective, and more pragmatic. OBJECTIVES: Our aim was to investigate the feasibility and performance of a pragmatic system for identifying patients with type 2 diabetes and impaired fasting glycaemia (IFG). METHODS: A clustered observational survey of the prevalence of diabetes and IFG was carried out in randomly selected patients from four at-risk groups. Patients were identified by computerized searching of practice databases for age and body mass index (BMI) risk criteria. Sixteen practices in South West England screened 1287 Caucasian patients from four groups with progressive levels of theoretical risk (age >70 and BMI >or=33, age >65 and BMI >or=31, age >60 and BMI >or=29, and age >50 and BMI >or=27). Fasting plasma glucose was measured and repeated if abnormal to determine the prevalence of new cases in each group. BMI and age data were validated against measures taken at the clinic. RESULTS: The response rate was 60.6% and the prevalence of new cases of type 2 diabetes in each group was 4.7% [95% confidence interval (CI) 2.8-7.7], 5.7% (95% CI 4.0-8.2), 3.8% (95% CI 2.4-6.0) and 2.6% (95%CI 1.4-4.7), respectively. An additional 5.2-8.4% had IFG. CONCLUSIONS: Targeted screening by searching existing GP records for age and BMI criteria is feasible for use in general practice in the UK. Screening of patients with a BMI of >or=27 and aged >50 by fasting glucose identified a substantial prevalence of undetected type 2 diabetes and IFG. The relative costs and benefits as well as the pragmatic advantages of different systems need further evaluation.

Adult↗
PubMed2000

A case of lead poisoning due to snooker chalk.

A 3 year, 9 month old child with pica presented with a blood lead concentration of 1.74 micromol/l (360 microg/l). The source of poisoning was snooker chalk (lead content 7200 microg/g). She was treated with intravenous calcium disodium edetate chelation. Thirty months later her blood lead was 0.39 micromol/l (80 microg/l). This case illustrates the need to be vigilant for more unusual causes of lead poisoning in the home.

Calcium Carbonate↗
PubMed2000

Correlation between plasma total homocysteine and copper in patients with peripheral vascular disease.

BACKGROUND: Increased concentrations of both plasma total homocysteine and copper are separately associated with cardiovascular disease. Correlations between plasma total homocysteine, trace elements, and vitamins in patients with peripheral vascular disease have not been investigated. METHODS: The concentrations of trace elements in plasma were determined by the multielement analytical technique of total-reflection x-ray fluorescence spectrometry. Plasma total homocysteine was determined by HPLC. RESULTS: In the univariate and multivariate regression analyses, copper was positively correlated with plasma total homocysteine in all subjects (coefficient +/- SE, 0.347 +/- 0.113; P = 0.0026 and coefficient +/- SE, 0.422 +/- 0.108; P = 0.0002, respectively), and in patients with peripheral vascular disease (coefficient +/- SE, 0.370 +/- 0.150; P = 0.016; and coefficient +/- SE, 0.490 +/- 0.151; P = 0.0025, respectively). Correlation between copper and plasma total homocysteine was not detected in healthy control subjects. The concentration of calcium in plasma (67.5 vs 80. 8 microg/g) was significantly lower in the patients than in the control subjects (P = 0.02). When the patients were divided into groups, the patients with suprainguinal lesions had significantly higher copper concentrations (P = 0.04) and significantly lower selenium and calcium concentrations (P = 0.01 and 0.008, respectively) than the healthy subjects. Patients had higher concentrations of autoantibodies against oxidized LDL and concentrations of thiobarbituric acid-reactive substance than the healthy subjects (P <0.0001 and P = 0.001, respectively). The concentrations of plasma total homocysteine and alpha-tocopherol were significantly higher, and the concentrations of vitamin B(6) and beta-carotene were lower in the patients than the healthy subjects. CONCLUSION: Our findings suggest that the atherogenicity of homocysteine may be related to copper-dependent interactions.

Antioxidants↗
PubMed1999

Radiation induced sarcoma of the head and neck.

BACKGROUND: Radiation-induced sarcoma of the head and neck (RISHN) is a long-term complication of treatment. The rarity of this tumour is reflected in the very few series reported in the English language medical literature. The incidence of RISHN is, however, likely to increase due to progressive aging of the population combined with improved survival in head and neck cancer patients resulting from better treatment regimes. Diagnosis and management of this problem can be extremely challenging and the overall outlook has been reported to be very bleak. As survival data from isolated case reports cannot be expected to provide reliable information on outcome, we have reviewed 69 cases reported in the English medical literature since 1966 and pooled this information with our experience in treatment of RISHN. PATIENTS AND METHODS: Ten patients with features of a RISHN were treated at the Royal Marsden Hospital between 1944 and 1997. The features of RISHN, treatment, and outcome were analysed in these patients. Additionally, 61 eligible patients with RISHN reported in the literature between 1966 and 1997 were pooled with nine of our patients to form the RISHN group (n = 70). This group was then compared for survival with 124 patients with a diagnosis of head and neck sarcoma registered on the Head and Neck Sarcoma database at the Royal Marsden Hospital (SHN group). Lifetables were constructed using the Kaplan-Meier method and compared using the log-rank test. RESULTS: There was no site of predilection for RISHN, but malignant fibrous histiocytoma (MFH) was the commonest pathological diagnosis. The period of latency between initial radiation therapy and diagnosis of RISHN ranged from 9 to 45 years with a median of 17 years. Surgery was the mainstay of treatment and follow-up ranged from 6 months to 15 years with a median of 48 months. The actuarial five-year disease free survival in these patients was 60%. CONCLUSION: There is at present little or no prospect for effective prevention of RISHN and therefore, a high index of suspicion based on the patient's symptoms assumes great importance in the outcome of these patients. Although surgical management of RISHN is challenging because of the close proximity of the tumour to important regional structures and the technical difficulties of operating in an irradiated area, complete surgical excision appears to offer the best means for palliation and the only realistic chance for long-term survival.

Adolescent↗
PubMed1998

A cytochrome P450 terpenoid hydroxylase linked to the suppression of insect juvenile hormone synthesis.

A cDNA encoding a cytochrome P450 enzyme was isolated from a cDNA library of the corpora allata (CA) from reproductively active Diploptera punctata cockroaches. This P450 from the endocrine glands that produce the insect juvenile hormone (JH) is most closely related to P450 proteins of family 4 and was named CYP4C7. The CYP4C7 gene is expressed selectively in the CA; its message could not be detected in the fat body, corpora cardiaca, or brain, but trace levels of expression were found in the midgut and caeca. The levels of CYP4C7 mRNA in the CA, measured by ribonuclease protection assays, were linked to the activity cycle of the glands. In adult females, CYP4C7 expression increased immediately after the peak of JH synthesis, reaching a maximum on day 7, just before oviposition. mRNA levels then declined after oviposition and during pregnancy. The CYP4C7 protein was produced in Escherichia coli as a C-terminal His-tagged recombinant protein. In a reconstituted system with insect NADPH cytochrome P450 reductase, cytochrome b5, and NADPH, the purified CYP4C7 metabolized (2E,6E)-farnesol to a more polar product that was identified by GC-MS and by NMR as (10E)-12-hydroxyfarnesol. CYP4C7 converted JH III to 12-trans-hydroxy JH III and metabolized other JH-like sesquiterpenoids as well. This omega-hydroxylation of sesquiterpenoids appears to be a metabolic pathway in the corpora allata that may play a role in the suppression of JH biosynthesis at the end of the gonotrophic cycle.

Amino Acid Sequence↗
PubMed1997

Cellular mechanisms of reactive oxygen metabolite generation from human polymorphonuclear leukocytes induced by crocidolite asbestos.

In our previous study, we demonstrated that reactive oxygen metabolites (ROM) generation from phagocytic cells may be involved in the carcinogenic mechanism of crocidolite asbestos. In the present study, the mechanism of human polymorphonuclear leukocytes (PMN) to generate ROM by crocidolite was investigated using verapamil, a calcium channel inhibitor; staurosporine, a NADPH oxidase inhibitor; and cytochalasin B (CB), an inhibitor of phagocytosis. The results indicate that whereas verapamil and staurosporine inhibited the crocidolite-induced ROM generation from PMN dose-dependently, CB caused an enhancement. We conclude that crocidolite-induced ROM generation involves a cell surface reaction due to influx of extracellular calcium through calcium channels and the activation of NADPH oxidase on the PMN cell membrane. This hypothesis was indirectly supported by dose-dependent enhancement of the ROM generation by CB, as CB increases calcium ion permeability in PMN. However, as in our previous studies, the time course of the ROM generation and the cell type difference suggested that ROM were also generated intracellularly from PMN due to phagocytosis of crocidolite. In conclusion, our evidence indicates that ROM generation from PMN by crocidolite involves cellular mechanisms related both to direct cell surface membrane interactions, together with an apparent phagocytic-dependent process.

Asbestos, Crocidolite↗
PubMed1997

Substrate specificity for the epoxidation of terpenoids and active site topology of house fly cytochrome P450 6A1.

Heterologous expression in Escherichia coli, purification, and reconstitution of house fly P450 6A1 and NADPH-cytochrome P450 reductase were used to study the metabolism of terpenoids. In addition to the epoxidation of cyclodiene insecticides demonstrated previously [Andersen et al. (1994) Biochemistry 33, 2171-2177], this cytochrome P450 was shown to epoxidize a variety of terpenoids such as farnesyl, geranyl, and neryl methyl esters, juvenile hormones I and III, and farnesal but not farnesol or farnesoic acid. P450 6A1 reconstituted with NADPH-cytochrome P450 reductase and phosphatidylcholine did not metabolize alpha-pinene, limonene, of the insect growth regulators hydroprene and methoprene. The four geometric isomers of methyl farnesoate were metabolized predominantly to the 10,11-epoxides, but also the 6,7-epoxides and to the diepoxides. The 10,11-epoxide of methyl (2E,6E)-farnesoate was produced in a 3:1 ratio of the (10S) and (10R) enantiomers. Monoepoxides of methyl farnesoate were metabolized efficiently to the diepoxides. Methyl farnesoate epoxidation was strongly inhibited by a bulky substituted imidazole. The active site topology of P450 6A1 was studied by the reaction of the enzyme with phenyldiazene to form a phenyl-iron complex. Ferricyanide-induced in situ migration of the phenyl group showed formation of the N-phenylprotopor-phyrinporphyrin IX adducts in a 17:25:33:24 ratio of the NB:NA:NC:ND isomers. These experiments suggest that metabolism of xenobiotics by this P450, constitutively overexpressed in insecticide-resistant strains of the house fly, is not severely limited by stereochemically constrained access to the active site.

Animals↗
PubMed1996

Surface chemistry and biological pathogenicity of silicates: an X-ray photoelectron spectroscopic study.

We extend our electron spectroscopy for chemical analysis studies of the chemistry of silicates to provide direct surface chemical information on the interactions involved in silicate-induced lung and tissue pathology. A total of five fibrous and non-fibrous silicate minerals, primarily amphiboles, have been studied: anthophyllite, tremolite, cummingtonite, hornblende and actinolite. We have followed the 'inlattice' surface chemistry of these materials and monitored features such as the simultaneous presence of four- and six-coordinate (with respect to oxygen) structural aluminium, and the presence of iron in the M4 octahedral positions. In vitro experiments involving contact of the silicate with cultured murine Ehrlich cells have identified modifications in the surface chemistry of Al, Mg and Fe in the silicates and changes in cellular iron content.

Animals↗
PubMed1994

Crocidolite-induced reactive oxygen metabolites generation from human polymorphonuclear leukocytes.

In order to study the mechanism of carcinogenicity of crocidolite asbestos, we have investigated the species of reactive oxygen metabolites (ROM) induced by crocidolite from human polymorphonuclear leukocytes (PMN) utilizing both an electron spin resonance (ESR) spin trapping method with 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and a luminol-dependent chemiluminescence (CL) method. The present study confirms the generation of OH. from human peripheral blood PMN stimulated by UICC crocidolite utilizing ESR. In addition, PMN incubated with 25-400 micrograms/ml of crocidolite produced CL, the intensity of CL increasing in a dose-dependent manner. Superoxide dismutase, catalase, and dimethyl sulfoxide, which are scavengers of O2-, H2O2, and OH., respectively, inhibited the production of crocidolite-stimulated CL from PMN, also in a dose-dependent manner. Sodium azide, an inhibitor of myeloperoxidase (MPO) to produce OCl-, also inhibited CL production. These results suggest the involvement of O2-, H2O2, OH., and OCl- in the production of CL by crocidolite-stimulated PMN. In conclusion, it is proposed that OH. is a key ROM species in the mechanism of crocidolite-induced carcinogenesis.

Asbestos, Crocidolite↗
PubMed1994

Biochemical indices and neuromuscular function tests in rural Gambian schoolchildren given a riboflavin, or multivitamin plus iron, supplement.

Ninety preselected children, aged between 8 and 14 years, living in two rural West African (Gambian) villages, were randomly divided into three groups, matched for age and sex. One group received a placebo (lactose) tablet, one received riboflavin (5 mg) on 5 d every week, which was sufficient to correct an endemic riboflavin deficiency, and one received a multivitamin supplement (Protovit; Hoffmann La Roche), on 5 d every week, together with FeSO4 (200 mg) once weekly, and the supplements were given for 1 year. Neuromuscular tests, including arm tremor and manipulative skills, were performed on three occasions: once just before the introduction of the supplements; again 6 weeks after commencing the supplements; and again 1 year later. Venous blood samples were collected at the same time as the first two sets of neuromuscular tests. These samples were used for haematology and nutrient status indices: plasma ferritin, ascorbic acid, cyanocobalamin and pyridoxal phosphate, and erythrocyte tests for folate status, for riboflavin status (erythrocyte glutathione reductase activation coefficient) and thiamine status (erythrocyte transketolase activation coefficient). The riboflavin in both supplements achieved a clear-cut response in biochemical status, which was dose-dependent. The pyridoxine, ascorbic acid and Fe components of the multivitamin also affected the associated biochemical indices. Although overall the arm tremor and related neuromuscular function tests did not respond significantly to the supplements, significant improvement was seen in the boys for the arm-tremor test in both the supplemented groups.

Adolescent↗