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Biomedical subjects

Frank H Wians

Publications and source records attributed to Frank H Wians.

14 recordsLinked to original sources
PubMed2006

Multicenter evaluation of the Bayer ADVIA Centaur HIV 1/O/2 enhanced (EHIV) assay.

BACKGROUND: It is important that serological assays detect antibodies to human immunodeficiency virus (HIV) in all infected individuals, including those infected with less prevalent, more diverse subtypes. METHODS: Performance of the ADVIA Centaur HIV 1/O/2 Enhanced (EHIV) Assay was tested on 1344 samples from HIV-positive subjects, 6061 samples from groups at low-risk for HIV infection, and 1042 samples from groups at high-risk for HIV-1 and HIV-2 infection. Results were compared with those of an FDA-approved predicate assay. RESULTS: The ADVIA Centaur EHIV Assay showed good precision with a diagnostic specificity of 99.9% and diagnostic sensitivity of 100%. HIV seroconversion was detected earlier in 6 panels, at the same time in 13 panels and later in only 1 of the panels when compared to the predicate assay, thereby narrowing the window period between infection and antibody detection. Of clinical significance, a blood donor sample that was indeterminate by HIV-1 Western blot and non-reactive by the predicate assay was repeatedly reactive in the ADVIA Centaur Assay and confirmed as positive by HIV-2 immunoblot. CONCLUSIONS: The ADVIA Centaur EHIV Assay is useful as an aid in the diagnosis of individuals infected with HIV-1 and/or HIV-2.

AIDS Serodiagnosis↗
PubMed2006

The variability of results between point-of-care testing glucose meters and the central laboratory analyzer.

CONTEXT: Point-of-care testing glucose meters are strongly recommended in the management of diabetes and are increasingly being used for making therapeutically important decisions. Thus, it is essential that their results correlate well with those of laboratory analyzers. OBJECTIVES: To test the reliability of point-of-care testing glucose meters. DESIGN: Two studies were performed: (1), an in-house study comparing accuracy of point-of-care testing glucose meters with a reference analyzer using fresh whole blood specimens (2), a real-time comparison of (a) 2 successive glucose meter readings and (b) glucose meter reading to central laboratory analyzer reading. SETTING: (1), Seven glucose meters from 4 manufacturers were compared with the Yellow Springs YSI 2300 blood glucose analyzer using whole blood without preservative. (2), (a) Whole blood samples were read within 5 minutes of each other using Accu-Chek meters and (b) between a glucose meter and a Hitachi laboratory analyzer. RESULTS: (1) Within the Accu-Chek group of glucose meters, fresh, preservative-free whole blood samples showed the lowest bias. (2) At the hypoglycemic level, successive glucose meter readings agreed well, but there was considerable disagreement between glucose meter and central laboratory values. Because laboratory analyzers are of proven accuracy, they are used as the reference. In the glucose meter-central laboratory analyzer correlation, for both hypoglycemic and hyperglycemic values, readings in which the differences were greater than 10% occurred more than 61% of the time. In the hypoglycemic range, differences greater than 20% occurred 57% of the time. CONCLUSIONS: One should scrutinize point-of-care testing glucose meter readings at the hypoglycemic and hyperglycemic levels and whenever possible to corroborate these clinical results with central laboratory analyzers.

Blood Chemical Analysis↗
PubMed2005

Relationship between C-reactive protein and subclinical atherosclerosis: the Dallas Heart Study.

BACKGROUND: Elevated levels of C-reactive protein (CRP) are associated with increased risk for incident cardiovascular events on the basis of observations from several prospective epidemiological studies. However, less is known regarding the relationship between CRP levels and atherosclerotic burden. METHODS AND RESULTS: We measured CRP in 3373 subjects 30 to 65 years of age who were participating in the Dallas Heart Study, a multiethnic, population-based, probability sample. Electron-beam CT scans were used to measure coronary artery calcification (CAC) in 2726 of these subjects, and MRI was used to measure aortic plaque in 2393. CRP levels were associated with most traditional cardiovascular risk factors. Subjects with CAC had higher median CRP levels than those without CAC (men: median, 2.4 versus 1.8 mg/L, P<0.001; women: median, 5.2 versus 3.6 mg/L, P<0.001), and there was a modest trend toward increasing CRP levels with increased CAC levels in men (P for trend=0.003) but not in women (P for trend=0.08). Male subjects with aortic plaque also had higher CRP levels than those without (median, 2.3 versus 1.8; P<0.001). In multivariate analysis adjusted for traditional cardiovascular risk factors, body mass index, and estrogen and statin medication use, the associations between CRP levels and CAC and CRP levels and aortic plaque were no longer statistically significant. CONCLUSIONS: In a large, population-based sample, subjects with higher CRP levels had a modest increase in the prevalence of subclinical atherosclerosis, but this association was not independent of traditional cardiovascular risk factors. CRP is a poor predictor of atherosclerotic burden.

Adult↗
PubMed2005

Impact of body mass and body composition on circulating levels of natriuretic peptides: results from the Dallas Heart Study.

BACKGROUND: The association between higher body mass index (BMI) and lower B-type natriuretic peptide (BNP) level is thought to be mediated by expression of the natriuretic peptide clearance receptor (NPR-C) in adipose tissue. To explore this association, we tested 2 hypotheses: (1) that N-terminal (NT)-proBNP, which is not believed to bind NPR-C, would not be associated with BMI and (2) that lower BNP would be more closely associated with fat mass than with lean mass. METHODS AND RESULTS: Measurements of BNP, NT-proBNP, and body composition by direct dual energy x-ray absorptiometry (DEXA) were performed in 2707 subjects from the Dallas Heart Study. The associations between obesity and low BNP (<4 ng/L) or low NT-proBNP (lowest sex-specific quartile) were evaluated with multivariable logistic regression models stratified by sex and adjusted for age, race/ethnicity, hypertension, left ventricular mass, and end-diastolic volume. Higher BMI was independently associated with lower BNP and NT-proBNP (all P<0.001). When BMI was replaced with both DEXA-derived lean and fat mass, greater lean mass, but not fat mass, was associated with low BNP and NT-proBNP levels. CONCLUSIONS: In a large, population-based cohort, we confirm the previously described association between higher BMI and lower BNP and demonstrate a similar inverse association between BMI and NT-proBNP. Interestingly, both BNP and NT-proBNP are more closely associated with lean mass than with fat mass. These findings do not support the hypothesis that the lower BNP levels seen in obesity are driven by enhanced BNP clearance mediated via NPR-C.

Absorptiometry, Photon↗
PubMed2005

Race and gender differences in C-reactive protein levels.

OBJECTIVES: This study sought to determine whether there are race and gender differences in the distribution of C-reactive protein (CRP) levels. BACKGROUND: Few data are available comparing CRP distributions in different race and gender groups. Recent clinical practice recommendations for CRP testing for cardiovascular risk assessment suggest a uniform threshold to define high relative risk (>3 mg/l). METHODS: We measured CRP in 2,749 white and black subjects ages 30 to 65 participating in the Dallas Heart Study, a multiethnic, population-based, probability sample, and compared levels of CRP between different race and gender groups. RESULTS: Black subjects had higher CRP levels than white subjects (median, 3.0 vs. 2.3 mg/l; p < 0.001) and women had higher CRP levels than men (median, 3.3 vs. 1.8 mg/l; p < 0.001). The sample-weight adjusted proportion of subjects with CRP levels >3 mg/l was 31%, 40%, 51%, and 58% in white men, black men, white women, and black women, respectively (p < 0.05 for each group vs. white men). After adjustment for traditional cardiovascular risk factors, estrogen and statin use, and body mass index, a CRP level >3 mg/l remained more common in white women (odds ratio [OR] 1.6; 95% confidence interval [CI] 1.1 to 2.5) and black women (OR 1.7; 95% CI 1.2 to 2.6) but not in black men (OR, 1.3; 95% CI, 0.8 to 1.9) when compared with white men. CONCLUSIONS: Significant race and gender differences exist in the population distribution of CRP. Further research is needed to determine whether race and gender differences in CRP levels contribute to differences in cardiovascular outcomes, and whether thresholds for cardiovascular risk assessment should be adjusted for different race and gender groups.

Adult↗
PubMed2005

Evaluation of the analytical performance characteristics of the Bayer ACS:180 B-type natriuretic peptide (BNP) assay.

BACKGROUND: B-type natriuretic peptide (BNP) is a cardiac hormone that regulates hemodynamic equilibrium and alleviates ventricular stress. In patients with chronic heart failure, BNP levels increase in proportion to the severity of clinical symptoms and degree of decreased left ventricular ejection fraction. BNP has clinical utility in the evaluation, management, and prognosis of patients with heart failure. METHODS: We evaluated the analytical performance characteristics of the BNP immunochemiluminometric assay in the ACS:180 instrument at three hospital laboratory sites. The analytical performance characteristics evaluated included imprecision, sensitivity (minimum detectable concentration, MDC), analytical measurement range (AMR), dilution linearity/recovery, lot-to-lot reagent variation, high-dose hook effect, and comparison against ADVIA Centaur BNP results on patients' EDTA-plasma samples. RESULTS: Total imprecision was <10% coefficient of variation at BNP concentrations of 43-1830 pg/ml; MDC was 6.9 pg/ml; AMR was 6.9-5000 pg/ml; overall recovery of BNP in samples diluted up to 1:10 was 98%; there was no lot-to-lot reagent variation in BNP results and no high-dose hook effect at BNP concentrations up to 100,000 pg/ml; and, ACS:180 results were highly correlated (r=0.996) with Centaur BNP results. CONCLUSIONS: The ACS:180 BNP assay demonstrated excellent analytical performance characteristics and agreement with BNP results obtained using the Centaur instrument.

Cardiac Output, Low↗
PubMed2004

ROC curves in clinical chemistry: uses, misuses, and possible solutions.

BACKGROUND: ROC curves have become the standard for describing and comparing the accuracy of diagnostic tests. Not surprisingly, ROC curves are used often by clinical chemists. Our aims were to observe how the accuracy of clinical laboratory diagnostic tests is assessed, compared, and reported in the literature; to identify common problems with the use of ROC curves; and to offer some possible solutions. METHODS: We reviewed every original work using ROC curves and published in Clinical Chemistry in 2001 or 2002. For each article we recorded phase of the research, prospective or retrospective design, sample size, presence/absence of confidence intervals (CIs), nature of the statistical analysis, and major analysis problems. RESULTS: Of 58 articles, 31% were phase I (exploratory), 50% were phase II (challenge), and 19% were phase III (advanced) studies. The studies increased in sample size from phase I to III and showed a progression in the use of prospective designs. Most phase I studies were powered to assess diagnostic tests with ROC areas >/=0.70. Thirty-eight percent of studies failed to include CIs for diagnostic test accuracy or the CIs were constructed inappropriately. Thirty-three percent of studies provided insufficient analysis for comparing diagnostic tests. Other problems included dichotomization of the gold standard scale and inappropriate analysis of the equivalence of two diagnostic tests. CONCLUSION: We identify available software and make some suggestions for sample size determination, testing for equivalence in diagnostic accuracy, and alternatives to a dichotomous classification of a continuous-scale gold standard. More methodologic research is needed in areas specific to clinical chemistry.

Chemistry, Clinical↗
PubMed2004

Rapid intraoperative immunoassay of parathyroid hormone and other hormones: a new paradigm for point-of-care testing.

BACKGROUND: The first description of the use of a rapid assay for the measurement of intact parathyroid hormone (PTH) in patients undergoing parathyroidectomy for hyperparathyroidism was reported in 1988. Subsequent improvements in the analytical performance of the rapid intraoperative PTH assay allowed the establishment of its clinical utility in the surgical management of hyperparathyroidism. These modifications also allowed the assay to be performed in or near the operating suite. METHODS: We searched MEDLINE, using the following key words: intraoperative, rapid, quick, parathyroid hormone, hormone, and immunoassay. Relevant articles that focused on the analytical aspects and clinical utility of rapid intraoperative hormone immunoassays were selected for this review. CONTENT: On the basis of the positive impact that the rapid intraoperative PTH test has had on both patient outcomes and cost savings, other rapid intraoperative hormone immunoassays for the diagnosis and/or treatment of other endocrine-hormone-secreting tumors have been developed. These hormones share certain characteristics that make them suitable for use as rapid intraoperative tests, i.e., short analyte half-life and/or large analyte concentration gradient, rapid analysis time, and positive clinical utility. Initial studies with cortisol, gastrin, insulin, adrenocorticotropic hormone, and testosterone have shown promising results in preoperative localization studies and/or for assessing the effectiveness of tumor resection during surgery. CONCLUSION: The emergence of these rapid intraoperative immunoassays indicates that this test format is likely to provide future opportunities to improve patient care by advances in clinical laboratory testing.

Clinical Laboratory Techniques↗
PubMed2004

Risk stratification for bladder tumor recurrence, stage and grade by urinary nuclear matrix protein 22 and cytology.

PURPOSE: To test the hypothesis that voided urinary levels of nuclear matrix protein 22 (NMP22) would add to the predictive ability of urine cytology in the diagnosis, staging and grading of bladder transitional cell carcinoma (TCC), and to evaluate the diagnostic performance of different NMP22 cut-points. MATERIALS: NMP22 level and barbotage cytology were evaluated in voided urine specimens collected before cystoscopy from 302 subjects with a history of TCC, 32 subjects with benign urologic pathologies, and 10 healthy volunteers. RESULTS: 180 patients (52%) had bladder TCC. Higher levels of NMP22 and positive cytology were independently associated with an increased risk of TCC, invasive stage, and high grade. The NMP22 value with equal sensitivity and specificity for prediction of bladder cancer was 6.5U/ml; for prediction of grade 3 TCC it was 13.5U/ml; and for prediction of invasive tumor stage it was 17.4U/ml. The NMP22 cut-point of 6.5U/ml outperformed the 10U/ml cut-point in all pathologic stages and grades. The diagnostic sensitivity of the cytology and NMP22 combined was superior across all pathologic stages and grades to that of either marker alone. NMP22 and cytology stratified patients into groups with significantly different risk for TCC presence, invasive stage, and high grade. CONCLUSIONS: 6.5U/ml is a robust NMP22 cut-point for bladder cancer surveillance. The diagnostic sensitivities of the combined NMP22 and cytology for TCC presence, stage, and grade were significantly higher than those of single marker alone. The combination of urine cytology and NMP22 could be used to tailor the frequency of cystoscopic follow up.

Adult↗
PubMed2003

A randomized, placebo-controlled trial of corticosteroids for hyperemesis due to pregnancy.

OBJECTIVE: Hyperemesis gravidarum, a severe form of nausea and vomiting due to pregnancy for which there is no proven pharmacological treatment, is the third leading cause for hospitalization during pregnancy. Corticosteroids are commonly used for the treatment of nausea and vomiting due to cancer chemotherapy-induced emesis and might prove useful in hyperemesis gravidarum. METHODS: A randomized, double-blind, placebo-controlled trial was conducted in 126 women who previously had not responded to outpatient therapy for hyperemesis gravidarum during the first half of pregnancy. Intravenous methylprednisolone (125 mg) was followed by an oral prednisone taper (40 mg for 1 day, 20 mg for 3 days, 10 mg for 3 days, 5 mg for 7 days) versus an identical-appearing placebo regimen. All women also received promethazine 25 mg and metoclopramide 10 mg intravenously every 6 hours for 24 hours, followed by the same regimen administered orally as needed until discharge. The primary study outcome was the number of women requiring rehospitalization for hyperemesis gravidarum. RESULTS: A total of 110 women delivered at our hospital and had pregnancy outcomes available for analysis; 56 were randomized to corticosteroids and 54 were administered placebo. Nineteen women in each study group required rehospitalization (34% versus 35%, P =.89, for corticosteroids versus placebo, respectively). CONCLUSION: The addition of parenteral and oral corticosteroids to the treatment of women with hyperemesis gravidarum did not reduce the need for rehospitalization later in pregnancy.

Adolescent↗
PubMed2003

The role of nutrition in preventing prostate cancer: a review of the proposed mechanism of action of various dietary substances.

BACKGROUND: Dietary modifications to prevent prostate cancer (PCa) continue to gain attention as research demonstrates that various dietary nutrients/supplements are related to decreased risk of developing prostate cancer (PCa). Several studies have focused on the antioxidant and nonantioxidant effects of various dietary substances in the prevention of PCa. Research into the mechanisms by which PCa is prevented, or its disease severity is reduced by dietary micronutrients and vitamins continues to enrich our understanding of the mechanisms by which PCa is initiated and progresses. METHODS: We reviewed the literature on dietary nutrients with antioxidant properties that have been shown to have a positive effect in reducing the incidence or preventing the occurrence of PCa including carotenoids (e.g., lycopene), retinoids (e.g., vitamin A), vitamin E, vitamin C, selenium, and polyphenols. Other nutrients examined included vitamin D and calcium. RESULTS: Many dietary micronutrients have demonstrated significant and complex effects on PCa cell proliferation, differentiation, and signaling related to the initiation, progression, and regression of PCa. CONCLUSION: Understanding the mechanisms by which various dietary nutrients exert their effects on PCa may make it possible to design effective drugs for treating PCa and to promote better nutrition and lifestyle changes in those at risk for PCa.

Antioxidants↗
PubMed2002

Evaluation of the clinical performance of equimolar- and skewed-response total prostate-specific antigen assays versus complexed and free PSA assays and their ratios in discriminating between benign prostatic hyperplasia and prostate cancer.

BACKGROUND: Prostate-specific antigen (PSA) exists in human serum in two principal forms, free PSA (fPSA) and protein-complexed PSA, predominantly PSA-ACT (alpha(1)-antichymotrypsin). Equimolar response (EMR) total PSA (tPSA) immunoassays measure each of these forms equally while skewed-response (SKR) assays overestimate or underestimate the tPSA concentration. The advantages of EMR over SKR tPSA assays are controversial. METHODS: We used five nonhuman serum-based samples each containing a different proportion of fSPA:PSA-ACT (0:100 to 100:0, %:%) and patients' serum samples from men with histologically confirmed benign prostatic hyperplasia (BPH) (n=94) or PCA (n=30) and a wide range of fPSA concentrations to investigate the molar response status of six tPSA assays. Receiver-operator characteristic (ROC) curve analysis was used to compare the discriminatory power of these assays in distinguishing men with BPH from those with PCA. RESULTS: The Bayer Immuno-1 tPSA (BtPSA) assay demonstrated EMR characteristics and diagnostic accuracy similar to the Hybritech Tandem-E and Tandem-R tPSA assays. At 90% sensitivity, EMR tPSA assays had higher specificity than SKR tPSA assays. CONCLUSIONS: The BtPSA assay is an EMR tPSA assay and EMR assays provide improved diagnostic specificity over SKR tPSA assays.

Adult↗