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Biomedical subjects

Enrico Rossi

Publications and source records attributed to Enrico Rossi.

14 recordsLinked to original sources
PubMed2006

Antioxidant inhibition of oxygen radicals for measurement of total antioxidant capacity in biological samples.

Few methods for assessing total antioxidant capacity (TAC) include both the percentage of inhibition and the length of inhibition in the measurement. Available methods require above ambient constant temperature incubation, reaction preheating, and/or separate assays for testing hydrophilic and hydrophobic samples. We describe a high-throughput method, antioxidant inhibition of oxygen radicals (AIOR), that overcomes these difficulties. AIOR uses peroxyl radicals to trigger a decrease in fluorescence of the indicator molecule, uroporphyrin I, which is delayed by the presence of antioxidants. The area under the curve is measured by a fluorescence spectrophotometer in a 96-well microplate format, and TAC results are expressed as millimole/liter Trolox equivalents. AIOR is performed at ambient temperature and is applicable to samples in either aqueous or common organic solvents. The reaction between uroporphyrin I and the peroxyl radicals generated from 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) was found to be of first-order kinetics with a mean rate constant (k) of 0.0254. Applications to measure antioxidant capacity are demonstrated on individual chemicals and biological samples. The method has good linearity, within- and between-assay precision, and recovery.

Antioxidants↗
PubMed2006

Clinical expression of C282Y homozygous HFE haemochromatosis at 14 years of age.

A 14-year-old boy who presented with debilitating lethargy was shown to have an elevated serum ferritin of 572 microg/L and a C282Y homozygous HFE genotype. Liver iron concentration was measured non-invasively by magnetic resonance imaging, which revealed a liver iron concentration of 59 micromol/g dry weight (children's reference range < 14). The early phenotypic expression was further investigated by screening genomic DNA for the presence of co-inherited mutations in genes responsible for non-HFE haemochromatosis. Coding regions and splice sites in genes encoding hepcidin and haemojuvelin were sequenced and previously described mutations in ferroportin 1 and transferrin receptor 2 genes were screened. Although no mutations were found, the most likely cause for the early expression is the presence of novel mutations or gene(s).

Adult↗
PubMed2006

Urine free cortisol analysis by automated immunoassay and high-performance liquid chromatography for the investigation of Cushing's syndrome.

BACKGROUND: We compared a widely used immunoassay method for urine free corticoids with a high-performance liquid chromatography (HPLC) method for the investigation of Cushing's syndrome. METHODS: Urine free corticoid analysis using an Immulite:2000 automated immunoassay analyser and urine free cortisol analysis by a specific HPLC method on 39 patients with an elevated baseline immunoassay 24 h urine free corticoid result who were referred from 2000 to 2004. RESULTS: Reference ranges for urine free corticoids by immunoassay and for urine free cortisol by HPLC were <900 and <170 nmol/day, respectively. Of the 39 patients with an elevated immunoassay urine free corticoid result, Cushing's syndrome was surgically proven in 22 patients, giving a positive predictive value of 56%. Cushing's syndrome was excluded in 12 of the remaining 17 patients by applying the specific HPLC method and at least one of the following: a clinical evaluation which was not suggestive or adequate suppression of plasma cortisol following dexamethasone. Urine free cortisol analysis by HPLC gave a positive predictive value of 81% for Cushing's syndrome. CONCLUSIONS: Although immunoassay has a low specificity for urine cortisol, it is a widely available test which serves as a valid initial investigation of Cushing's syndrome.

Adolescent↗
PubMed2005

Interlayer transport in bilayer quantum Hall systems.

Bilayer quantum Hall systems have a broken symmetry ground state at a filling factor which can be viewed either as an excitonic superfluid or as a pseudospin ferromagnet. We present a theory of interlayer transport in quantum Hall bilayers that highlights remarkable similarities and critical differences between transport in Josephson junction and ferromagnetic metal spin-transfer devices. Our theory is able to explain the size of the large but finite low-bias interlayer conductance and the voltage width of this collective transport anomaly.

Journal Article↗
PubMed2005

Folate levels and cancer morbidity and mortality: prospective cohort study from Busselton, Western Australia.

PURPOSE: To test a community population for the hypothesis that carcinogenesis is related to blood folate levels. METHODS: Prospective analysis of cancer mortality data for a cohort of 964 men (person-time follow up: 20,254 years) and 1024 women (person-time follow up: 24,970 years) and morbidity data for a subcohort, all of whom participated in the 1969 Busselton (Western Australia) Health survey. Outcome measures were adjusted hazard ratios according to baseline folate levels for total cancer mortality and morbidity and site specific mortality and morbidity for colorectal, lung, breast, and prostate cancers. RESULTS: In total, there were 278 cancer deaths--45 from colorectal cancer, 44 from lung cancer, 15 from breast cancer, and 31 from prostate cancer. Decreased serum folate levels showed an independent association with increased prostate cancer mortality risk, the adjusted hazard ratio per decrease of 2 microg/L was 1.56 (CI: 1.05, 2.38), men whose levels were in the lowest quartile had an adjusted hazard ratio of 4.79 (CI: 1.56, 14.43) for subsequent death from prostate cancer. The morbidity subcohort data showed that decreased red blood-cell folate was significantly associated with increased events due to breast cancer, the adjusted hazard ratio per decrease of 100 mug/L was 1.96 (CI: 1.22, 3.12), women in the lowest quartile of red cell folate levels had an adjusted hazard ratio of 6.46 (CI: 1.19, 35.07) for a subsequent breast cancer event. Mortality and morbidity from colorectal or lung cancers were not associated with folate levels. CONCLUSIONS: Independent associations, assessed over periods greater than 20 years, were demonstrated between decreased folate levels and increased risks of prostate cancer mortality and breast cancer morbidity.

Adult↗
PubMed2005

Hepascore: an accurate validated predictor of liver fibrosis in chronic hepatitis C infection.

BACKGROUND: Staging hepatic fibrosis by liver biopsy guides prognosis and treatment of hepatitis C, but is invasive and expensive. We sought to create an algorithm of serum markers that accurately and reliably predict liver fibrosis stage among hepatitis C patients. METHODS: Ten biochemical markers were measured at time of liver biopsy in 117 untreated hepatitis C patients (training set). Multivariate logistic regression and ROC curve analyses were used to create a predictive model for significant fibrosis (METAVIR F2, F3, and F4), advanced fibrosis (F3 and F4), and cirrhosis (F4). The model was validated in 104 patients from other institutions. RESULTS: A model (Hepascore) of bilirubin, gamma-glutamyltransferase, hyaluronic acid, alpha(2)-macroglobulin, age, and sex produced areas under the ROC curves (AUCs) of 0.85, 0.96, and 0.94 for significant fibrosis, advanced fibrosis, and cirrhosis, respectively. In the training set, a score > or = 0.5 (range, 0.0-1.0) was 92% specific and 67% sensitive for significant fibrosis, a score <0.5 was 81% specific and 95% sensitive for advanced fibrosis, and a score <0.84 was 84% specific and 71% sensitive for cirrhosis. Among the validation set, the AUC for significant fibrosis, advanced fibrosis, and cirrhosis were 0.82, 0.90, and 0.89, respectively. A score > or = 0.5 provided a specificity and sensitivity of 89% and 63% for significant fibrosis, whereas scores <0.5 had 74% specificity and 88% sensitivity for advanced fibrosis. CONCLUSIONS: A model of 4 serum markers plus age and sex provides clinically useful information regarding different fibrosis stages among hepatitis C patients.

Adult↗
PubMed2004

Expression of the HFE hemochromatosis gene in a community-based population of elderly women.

BACKGROUND AND AIM: Recent studies suggest that the clinical penetrance of associated hereditary hemochromatosis, defined as either the C282Y homozygote or compound heterozygote HFE genotype status, is much lower than previously thought. METHODS: We investigated the clinical penetrance and phenotypic expression of HFE-associated hereditary hemochromatosis in a community-based population of 1352 elderly female subjects with a mean age of 75 years. Serum transferrin saturation and ferritin levels were determined on all subjects bearing a C282Y mutation and a subset of wild-type C282Y subjects. RESULTS: The prevalences of the C282Y homozygous and compound heterozygous HFE genotypes were 0.15% (2/1352) and 2.0% (27/1352), respectively. The observed prevalence of 0.15% for C282Y homozygotes borders on significance (P = 0.054) for deviation from the Hardy-Weinberg population equilibrium calculations, which predict a prevalence of 0.49%, whereas the observed and predicted compound heterozygote prevalences were not significantly different. Clinical symptoms of hemochromatosis were absent in both the C282Y homozygote subjects. Of the compound heterozygous subjects, 2/27 (7%) had elevated serum transferrin saturation and ferritin values; however, clinical symptoms of hemochromatosis were absent in both. Considered as a whole, the compound heterozygous subjects had markedly elevated means for serum iron (19.4 vs 16.0 micromol/L, P = 0.0008), transferrin saturation (34.8% vs 25.2%, P < 0.0001) and ferritin (157 vs 92 microg/L, P = 0.002) compared with the wild-type subjects. CONCLUSION: The C282Y homozygous HFE hereditary hemochromatosis genotype was under-represented in this elderly cohort, whereas the compound heterozygous genotype was not. None of the homozygous or compound heterozygous subjects expressed the phenotype of iron overload disease.

Aged↗
PubMed2004

Hepatic iron loading in patients with compound heterozygous HFE mutations.

AIM: To assess the severity of hepatic iron loading in patients with a compound heterozygous C282Y/H63D HFE genotype. METHODS: A total of 246 patients were referred to the Hepatology Clinic at a tertiary hospital for HFE genotyping and further assessment of elevated serum transferrin saturation and/or ferritin results, either with or without abnormal liver function tests. Subjects of the study were 19 patients compound heterozygous for HFE who had liver biopsy, quantitative liver iron estimation and liver histopathology. RESULTS: Mild iron overload [hepatic iron concentration between 30 and 100 micromol/g dry weight], was present in 16/19 compound heterozygous patients, three patients had values within the reference range. As well as the compound heterozygous HFE genotype, 18/19 patients were found to have had at least one additional risk factor for developing either iron loading or liver disease. CONCLUSION: Compound heterozygous patients show no more than mild liver iron loading. The decision whether or not to recommend liver biopsy in C282Y/H63D patients with abnormal serum iron indices and/or liver function tests should be based on the need to evaluate liver damage rather than solely to assess liver iron loading.

Adult↗
PubMed2003

Validation of the FibroTest biochemical markers score in assessing liver fibrosis in hepatitis C patients.

BACKGROUND: Determining the stage of fibrosis by liver biopsy is important in managing patients with hepatitis C virus infection. We investigated the predictive value of the proprietary FibroTest score to accurately identify significant fibrosis in Australian hepatitis C patients. METHODS: Serum obtained from 125 confirmed hepatitis C patients before antiviral therapy was analyzed for haptoglobin, alpha(2)-macroglobulin, apolipoprotein A1, bilirubin, and gamma-glutamyltransferase activity, and the FibroTest score was computed. Liver fibrosis pathology was staged according to a defined system on a scale of F0 to F4. We used predictive values and a ROC curve to assess the accuracy of FibroTest scores. RESULTS: The prevalence of significant fibrosis defined by liver biopsy was 0.38. The most useful single test for predicting significant fibrosis was serum alpha(2)-macroglobulin (cutoff value, 2.52 g/L; sensitivity, 75%; specificity, 67%). The negative predictive value of a FibroTest score <0.1 was 85%, and the positive predictive value of a score >0.6 was 78%. Although 33 of the 125 patients had FibroTest scores <0.1 and were therefore deemed unlikely to have fibrosis, 6 (18%) had significant fibrosis. Conversely, of the 24 patients with scores >0.6 who were likely to have significant fibrosis, 5 (21%) had mild fibrosis. Of the 125 patients in the cohort, 57 (46%) could have avoided liver biopsy, but discrepant results were recorded in 11 of those 57 (19%). CONCLUSION: The FibroTest score could not accurately predict the presence or absence of significant liver fibrosis.

Adult↗
PubMed2002

A population-based study of the biochemical and clinical expression of the H63D hemochromatosis mutation.

BACKGROUND & AIMS: Two major mutations are defined within the hemochromatosis gene, HFE. Although the effects of the C282Y mutation have been well characterized, the effects of the H63D mutation remain unclear. We accessed a well-defined population in Busselton, Australia, and determined the frequency of the H63D mutation and its influence on total body iron stores. METHODS: Serum transferrin saturation and ferritin levels were correlated with the H63D mutation in 2531 unrelated white subjects who did not possess the C282Y mutation. RESULTS: Sixty-two subjects (2.1%) were homozygous for the H63D mutation, 711 (23.6%) were heterozygous, and 1758 (58.4%) were wild-type for the H63D mutation. Serum transferrin saturation was significantly increased in male and female H63D homozygotes and heterozygotes compared with wild-types. Serum ferritin levels within each gender were not influenced by H63D genotypes. Elevated transferrin saturation > or = 45% was observed in a greater proportion of male H63D carriers than male wild-types. Male H63D homozygotes (9%) and heterozygotes (3%) were more likely to have both elevated transferrin saturation and elevated ferritin > or = 300 ng/mL than male wild-types (0.7%). Homozygosity for H63D was not associated with the development of clinically significant iron overload. CONCLUSIONS: Presence of the H63D mutation results in a significant increase in serum transferrin saturation but does not result in significant iron overload. In the absence of the C282Y mutation, the H63D mutation is not clinically significant.

Adult↗
PubMed2002

Serum levels of micronutrients, antioxidants and total antioxidant status predict risk of breast cancer in a case control study.

We performed a case control study to assess the association between serum micronutrient and antioxidant levels and the risk of breast cancer. Newly diagnosed breast cancer cases were recruited before any treatment and matched with controls randomly selected from the electoral roll. Blood samples were collected from 153 breast cancer cases and 151 controls. Serum samples were analyzed for retinol, alpha-tocopherol, lycopene, alpha- and beta-carotene by HPLC, and total antioxidant status by the Trolox-equivalent antioxidant assay. Serum albumin, bilirubin and uric acid levels were also determined. After adjustment for age at menarche, parity, dietary fat and alcohol intake, we observed the following reductions in odds ratios for breast cancer risk comparing the highest with the lowest quartiles: 0.47 [95% confidence interval (CI) 0.24, 0.91] for beta-carotene; 0.53 (CI 0.28, 1.01) for retinol; 0.50 (CI 0.26, 0.97) for bilirubin and 0.47 (CI 0.24, 0.94) for total antioxidant status. We conclude that increased serum levels of beta-carotene, retinol, bilirubin and total antioxidant status are associated with reductions in breast cancer risk.

Antioxidants↗
PubMed2002

Effects of body iron stores and haemochromatosis genotypes on coronary heart disease outcomes in the Busselton health study.

BACKGROUND: Increased iron stores and haemochromatosis gene mutations may be risk factors for coronary heart disease. The aims of this study were to determine in a stable community population whether increased iron stores or haemochromatosis gene mutations were risk factors for coronary heart disease. DESIGN: Cross-sectional and prospective cohort studies. METHODS: We evaluated 1185 men and 1141 women aged 20-79 years of predominantly Anglo-Celtic descent from the 1994-95 assessment of the Busselton population in Western Australia. Subjects underwent haemochromatosis genotyping, serum iron studies, clinical, biochemical and ECG evaluation for coronary heart disease and associated risk factors. Hospital admissions or death from cardiovascular disease were determined by linkage with the Western Australian morbidity and mortality database. The study design was cross-sectional for the 1994-95 cohort comparing coronary heart disease cases with unaffected subjects and unaffected subjects were followed prospectively until December 1998. RESULTS: Cross-sectional and prospective cohort analyses demonstrated that elevated serum iron parameters or possession of either the C282Y or H63D mutations in the gene were not predictive of increased risk for coronary heart disease in men or women. CONCLUSIONS: Increased iron stores or haemochromatosis gene mutations are not significant risk factors for coronary heart disease.

Adult↗