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PubMed2003

Methodologic and statistical considerations regarding use of biomarkers of nutritional exposure in epidemiology.

In nutritional epidemiology, accurate quantification of nutritional exposure is critical. Even moderate flaws in measurement can lead to sizeable distortions in estimations of the effects of exposure. In many situations, this will lead to inaccurate direct estimation of exposure effects. In others, it will make it difficult to control for the confounding effects of nutritional exposure. Biomarkers offer important opportunities to advance research in nutritional epidemiology; their objectivity and potentially greater accuracy give them the potential to substantially lessen distortions that might result from imperfect measurements. Clearly, the accuracy of biomarkers as indicators of nutritional exposure is critical to their value. It is likely that establishing the accuracy of biomarkers will require some reference to self-reports, even if those reports are not as accurate as the biomarkers they are used to test. The goal of this paper is to describe aspects of accuracy-reproducibility, reliability and validity-as they apply to biomarkers in nutritional epidemiology.

Biomarkers↗
PubMed2005

Pulmonary hypertension: classification and diagnostic algorithm.

Pulmonary arterial hypertension (PAH) is defined as a group of diseases characterized by a progressive increase in pulmonary vascular resistance leading to right ventricular failure and premature death. Recently, the diagnostic approach has been more clearly defined according to the new clinical classification and with consensus reached on algorithms of various investigative tests and procedures that exclude other causes and ensure an accurate diagnosis of PAH. The diagnostic procedures include clinical history and physical examination, ECG, chest X-ray, transthoracic Doppler echocardiography, pulmonary function tests, arterial blood gas analysis, ventilation and perfusion lung scan, high-resolution computed tomography of the lungs, contrast-enhanced spiral computed tomography of the lungs and pulmonary angiography, blood tests and immunology, abdominal ultrasound scan, exercise capacity assessment, and hemodynamic evaluation. Invasive and non-invasive markers of disease severity, either biomarkers or physiological parameters and tests that can be widely applied, have been proposed to reliably monitor the clinical course.

Algorithms↗
PubMed1998

Cardiac biomarkers: past, present, and future.

Accurate recognition of signs and symptoms and prompt diagnosis of myocardial infarction are essential for preserving myocardial function and saving lives. However, measurements of cardiac enzymes such as creatine kinase, lactate dehydrogenase, and their isoenzymes do not always provide accurate clinical diagnosis, particularly in patients with other concomitant diseases. Recently, alternative biomarkers of cardiac disease have been described: creatine kinase mass, cardiac troponins, and myoglobin. All cardiac biomarkers have some clinical usefulness in diagnosing acute coronary syndrome and acute myocardial infarction. Indications for use vary for each biomarker, and each has advantages and disadvantages and can be used at various times. However, the following must be considered: (1) Serial testing is essential with any biomarker. (2) None of the current biomarkers can be used to detect myocardial ischemia. (3) The decision of which biomarker to use should be based on the capabilities of the healthcare facility and the signs and symptoms of the patient.

Biomarkers↗
PubMedDate not supplied

Molecular markers of prostate cancer.

Although prostate-specific antigen (PSA) has evolved as a very useful tool for detection of prostate cancer, there remains an urgent need for more accurate biomarkers to diagnose prostate cancer and predict cancer-related outcomes. Recent advances in the study of proteomics and high throughput techniques have led to the discovery of many potential biomarkers for prostate cancer. This article briefly reviews the current status of PSA testing and discusses several candidate protein biomarkers for prostate cancer, as well as highlighting some recent proteomic discoveries with the potential to supplement or even replace PSA for the diagnosis and prognosis of prostate cancer.

Biomarkers, Tumor↗
PubMed2005

Biomarkers in chronic kidney disease: utility and issues towards better understanding.

PURPOSE OF REVIEW: Biomarkers are substances that reflect the presence of a given disease, its pathophysiology or organ damage. These indicators are increasingly proposed to assess prognosis or the response to treatment. This review examines the value of a series of biomarkers which have been recently tested in prospective studies in chronic kidney disease and end-stage renal disease patients. RECENT FINDINGS: C reactive protein has coherently emerged as an early marker of renal dysfunction. The usefulness of this measurement for predicting the evolution of chronic kidney disease or for monitoring the response to renoprotective treatment, however, still remains unproven. On the other hand the measurement of C reactive protein can be recommended for monitoring the risk of atherosclerotic complications in patients with chronic kidney disease and end-stage renal disease, particularly in those with evidence of coronary heart disease or other cardiovascular complications (i.e. in the vast majority of patients followed up in nephrology clinics). There is growing interest in homocysteine and asymmetric dimethyl arginine as biomarkers of cardiovascular and renal risk but the usefulness of these biomarkers in clinical practice remains to be proven. Brain natriuretic peptide and troponin T are strongly related to cardiovascular outcomes in end-stage renal disease patients but their value in this population still requires to be proper tested in specifically designed intervention studies. SUMMARY: Among emerging biomarkers C reactive protein is the only one which is very near to fulfilling the methodological requirements for being recommended in clinical practice.

Animals↗
PubMed2005

Translational crossroads for biomarkers.

A group of investigators met at a Specialized Programs of Research Excellence Workshop to discuss key issues in the translation of biomarker discovery to the development of useful laboratory tests for cancer care. Development and approval of several new markers and technologies have provided informative examples that include more specific markers for prostate cancer, more sensitive tests for ovarian cancer, more objective analysis of tissue architecture and an earlier indication of response to treatment in breast cancer. Although there is no clear paradigm for biomarker development, several principles are clear. Marker development should be driven by clinical needs, including early cancer detection, accurate pretreatment staging, and prediction of response to treatment, as well as monitoring disease progression and response to therapy. Development of a national repository that uses carefully preserved, well-annotated tissue specimens will facilitate new marker development. Reference standards will be an essential component of this process. Both hospital-based and commercial laboratories can play a role in developing biomarkers from discovery to test validation. Partnering of academe and industry should occur throughout the process of biomarker development. The National Cancer Institute is in a unique position to bring together academe, industry, and the Food and Drug Administration to (a) define clinical needs for biomarkers by tumor type, (b) establish analytic and clinical paradigms for biomarker development, (c) discuss ways in which markers from different companies might be evaluated in combination, (d) establish computational methods to combine data from multiple biomarkers, (e) share information regarding promising markers developed in National Cancer Institute-supported programs, and (f) exchange data regarding new platforms and techniques that can accelerate marker development.

Antineoplastic Agents↗
PubMedDate not supplied

Carbohydrate-deficient transferrin: validity of a new alcohol biomarker in a sample of patients with diabetes and hypertension.

OBJECTIVE: To test the reliability and validity of a new alcohol biomarker. DESIGN: Cross-sectional with matched control. Alcohol use, symptoms of alcohol dependence, health status, current medications, carbohydrate-deficient transferrin (CDT) levels, and gamma-glutamyl transferase levels were assessed. Validity of the %CDT test was estimated using a drinking cutoff of 90 or more drinks in the previous 30 days. PARTICIPANTS: Sample (n = 799) included 89 patients with type 2 diabetes, 299 patients with hypertension, 209 patients with hypertension and type 2 diabetes, and 202 matched control subjects with neither diabetes nor hypertension. RESULTS: Three hundred ninety-six women and 403 men ages 30 to 60 participated in the study. Six percent (45 of 799) reported drinking more than 14 drinks per week, 2% (n = 17) met criteria for alcohol abuse, and 3% (n = 23) met DSM-IV criteria for dependence. The overall sensitivity of the %CDT test was 61% with a specificity of 85%. A receiver operating characteristic curve was used to determine that the best fit was for persons who reported >90 drinks per month and a CDT level >2.5% with an area under the curve of 0.83. Test-retest reliability (R) was 0.94. CONCLUSIONS: %CDT levels are useful in detecting and/or confirming high-risk drinking in patients being treated for type 2 diabetes and hypertension.

Adult↗
PubMedDate not supplied

Military deployment human exposure assessment: urine total and isotopic uranium sampling results.

Currently the Department of Defense (DoD) does not use exposure biomarkers to measure service members' exposure to environmental chemicals. Blood and urine exposure biomarkers for volatile organic compounds (VOC), selected heavy metals, depleted uranium (DU), and chemical warfare agents are currently available but have not been field tested or validated by the DoD in military deployments as a tool to document exposures. The Military Deployment Human Exposure Assessment Study, a prospective cohort of 46 soldiers deployed to Bosnia, was designed to field test blood and urine exposure biomarkers as a mechanism to document exposures to these chemicals during military deployments. Blood and urine were collected before, during, and after deployment. Standard questionnaire, environmental, and occupational monitoring data collection methods were conducted for comparison to the exposure biomarker results. This article compares and reports the pre-, during, and postdeployment urine total and isotopic uranium measurements and compares them to perceived exposures captured on questionnaire, to environmental data collected by the United Nations Environmental Program in Bosnia, and to standard U.S. urine uranium reference levels (CDC, 2003). Additionally, the questionnaire and environmental and occupational measurements are reported. The results of the study indicate that exposure biomarkers may be a valuable tool to the DoD in exposure and risk assessment with regard to environmental and occupational exposures to uranium.

Bosnia and Herzegovina↗
PubMed1997

Breast cytology and biomarkers obtained by random fine needle aspiration: use in risk assessment and early chemoprevention trials.

In a prospective pilot study, we performed breast fine needle aspirations (FNAs) on 224 high-risk and 30 low-risk women and analyzed these aspirates for cytologic changes and biomarker abnormalities of aneuploidy and overexpressed estrogen receptor (ER), epidermal growth factor receptor (EGFR), p53 and HER-2/neu. High-risk women had a first-degree relative with breast cancer (74%), prior biopsy indicating premalignant breast disease (25%), a history of breast cancer (13%), or some multiple of these risk factors (12%). Median ages of the high- and low-risk groups were 44 and 42, respectively. Seventy percent of high-risk and 17% of low-risk women had cytologic evidence of hyperplasia with or without atypia (P < .0001). Aneuploidy and overexpression of EGFR and p53 occurred in 27, 37, and 29% of high-risk subjects but only 0, 3, and 3% of low-risk subjects (P < .0023). Overexpression of ER and HER-2/neu occurred in 7 and 20% of high-risk women but in none of the low-risk subjects. Biomarker abnormalities were more frequent with increasing cytologic abnormality. Restricting the analysis to those 3 biomarkers most frequently overexpressed in the high-risk group (ploidy, EGFR, p53), 13% of high-risk women with normal cytology, 19% of high-risk women with epithelial hyperplasia, and 49% of high-risk women with hyperplasia with atypia had abnormalities of 2 or more of these 3 biomarkers (P = .00004). At a median follow-up of 32 months, four women have been diagnosed with invasive cancer and two with ductal carcinoma in situ (DCIS). Later detection of these neoplastic conditions was associated (P < or = .016) by univariate analysis with prior FNA evidence of hyperplasia with atypia; overexpression of p53 and EGFR; the modified Gail risk of breast cancer development at 10 years; and multiple biomarker abnormalities. By multivariate analysis, later detection of cancer was primarily predicted by the number of biomarker abnormalities in the 3-test battery (P = .0005) and secondarily by the Gail risk at 10 years (P = .0049). In turn, hyperplasia with atypia was associated with multiple biomarker abnormalities, particularly p53 and EGFR overexpression. Thus, hyperplasia with atypia and cytologic markers in breast FNAs have promise as risk predictors and as surrogate endpoint biomarkers for breast cancer chemoprevention trials.

Adult↗
PubMedDate not supplied

Changes in serological biomarkers of liver function and connective tissue turnover in chronic hepatitis B during lamivudine therapy.

Assessment of hepatic damage associated with chronic hepatitis B (CHB) currently relies on measurement of serum transaminases and assessment of hepatic histology. It was determined serum hepatic function tests and the liver fibrosis biomarkers type IV collagen (CIV), amino-terminal propeptide of type I procollagen (PINP), amino-terminal propeptide of type III procollagen (PIIINP) and carboxy-terminal telopeptide of type I collagen (ICTP) were of value in monitoring the effect of lamivudine therapy for CHB. Thirty-nine patients received orally 100 mg lamivudine daily for 48 weeks. Blood samples were obtained at baseline, 24 and 48 weeks. At the end of the treatment period, the patients were then divided into four groups according to the pattern of HBs and HBe antigens. At baseline, alanine aminotransferase, aspartate aminotransferase, PIIINP and the PINP/ICTP ratio and at 24 weeks alanine aminotransferase, aspartate aminotransferase and the PINP/ICTP ratio had lower values in the complete response compared with complete failure groups. Using receiver-operated curve analysis, only the PINP/ICTP ratio at baseline (area under the curve 0.806) and ALT and the PINP/ICTP ratio at 24 weeks (areas under the curve 0.803 and 0.776, respectively) had significant diagnostic ability in detecting responders. In conclusion, the PINP/ITCP ratio is sensitive and specific in detecting responders to treatment.

Adult↗
PubMed1998

13th Meeting of the Scientific Group on Methodologies for the Safety Evaluation of Chemicals (SGOMSEC): alternative testing methodologies for ecotoxicity.

There is growing public pressure to minimize the use of vertebrates in ecotoxicity testing; therefore, effective alternatives to toxicity tests causing suffering are being sought. This report discusses alternatives and differs in some respects from the reports of the other three groups because the primary concern is with harmful effects of chemicals at the level of population and above rather than with harmful effects upon individuals. It is concluded that progress toward the objective of minimizing testing that causes suffering would be served by the following initiatives--a clearer definition of goals and strategies when undertaking testing procedures; development of alternative assays, including in vitro test systems, that are based on new technology; development of nondestructive assays for vertebrates (e.g., biomarkers) that do not cause suffering; selection of most appropriate species, strains, and developmental stages for testing procedures (but no additional species for basic testing); better integrated and more flexible testing procedures incorporating biomarker responses, ecophysiological concepts, and ecological end points (progress in this direction depends upon expert judgment). In general, testing procedures could be made more realistic, taking into account problems with mixtures, and with volatile or insoluble chemicals.

Animal Testing Alternatives↗