bluuebunny/crossref_metadata_2025 huggingface dataset:
Screening for Interference in Immunoassays
Authors: Emerson Jane F , Ngo Gilda , Emerson Scott S
Published: February 2004

Background: The presence of interfering substances in patient samples submitted for immunoassay cannot be reliably anticipated. We therefore evaluated three interference screening techniques and estimated the prevalence of interfering substances as defined by positive outcomes with these protocols.

Methods: We evaluated 160 samples for the presence of substances that may interfere with four immunoassays (40 samples for each): thyroid-stimulating hormone, prostate-specific antigen, β-human chorionic gonadotropin, and cortisol. Interference was defined by nonlinear responses with serial dilution, discrepant results after pretreatment with heterophile blocking reagent (HBR), and positive reactions on a mouse-antibody-negative control reaction (Tandem ICON® ImmunoConcentration HCG). Criteria for declaring significant discrepant results were based on a Z-score computed using the assay CV. The McNemar test was used to compare the prevalence of discrepancies across the three screening techniques. The association between type of immunoassay and prevalence of discrepant results was determined by a modified Pearson χ2 statistic.

Results: Five of the 160 samples [3.1%; 95% confidence interval (CI), 1.0–7.1%] screened positive with the ICON. Seventy-two of the 148 samples with informative serial dilutions (48.6%; 95% CI, 40.4–57.0%) had at least one discrepant result at higher dilutions. After pretreatment with HBR, 53 of the 140 samples (38%; 95% CI, 29.8–46%) were discrepant. Only 48 of the 140 samples with informative measurements for all three screening techniques (34%; 95% CI, 26–43%) were negative by all three. The prevalence of positive screens varied significantly by type of immunoassay (P <0.0001) for both HBR and serial dilution. Only 3% (0.8–7%) of the samples tested with HBR showed a change from normal to abnormal or the reverse after treatment.

Conclusions: Introducing a protocol based on any of these three techniques into the immunochemistry laboratory to prescreen for interfering substances is not warranted. The evaluation of specimens for the presence of interfering anti-animal antibodies should be reserved for cases in which clinical history or suspicious results indicate the need.
Optimal Sampling Strategies to Assess Inulin Clearance in Children by the Inulin Single-Injection Method
Authors: van Rossum Lyonne K , Mathot Ron A A , Cransberg Karlien , Vulto Arnold G
Published: February 2004

Background: Glomerular filtration rate in patients can be determined by estimating the plasma clearance of inulin with the single-injection method. In this method, a single bolus injection of inulin is administered and several blood samples are collected. For practical and convenient application of this method in children, it is important that a minimal number of samples are drawn. The aim of this study was to develop and validate sampling strategies with fewer samples for reliable prediction of inulin clearance in pediatric patients by the inulin single-bolus-injection method.

Methods: Complete inulin plasma concentration-time curves of 154 patients were divided into an index (n = 100) and a validation set (n = 54). A population pharmacokinetic model was developed for the index set. Optimal sampling times were selected based on D-optimality theory. For the validation set, Bayesian estimates of clearance were generated using the derived population parameters and concentrations at two to four sampling times. Bayesian estimates of clearance were compared with the individual reference values of clearance.

Results: The strategies with samples taken at 10/30/90/240 min, 10/30/240 min, 10/90/240 min, 30/90/240 min, and 90/240 min allowed accurate prediction of inulin clearance (bias <3% and not significantly different from 0; imprecision <15%).

Conclusions: Strategies involving two to four samples, including a sample at 240 min after administration of inulin, in the inulin single-injection method allow accurate prediction of inulin clearance in pediatric patients. Even one blood sample at 240 min showed acceptable performance. The proposed strategies are practical and convenient to children, and reduce repetitive blood sampling without compromising accuracy.
Practical Considerations for the Measurement of Free Light Chains in Serum
Authors: Tate Jillian R , Gill Devinder , Cobcroft Ralph , Hickman Peter E
Published: February 2004

Background: A new immunoassay for free light chain measurements has been reported to be useful for the diagnosis and monitoring of monoclonal light chain diseases and nonsecretory myeloma. We describe experience with and some potential pitfalls of the assay.

Methods: The assay was assessed for precision, sample type and stability, recovery, and harmonization of results between two analyzers on which the reagents are used. Free-light-chain concentrations were measured in healthy individuals (to determine biological variation), patients with monoclonal gammopathy of undetermined significance, myeloma patients after autologous stem cell transplants, and patients with renal disease.

Results: Analytical imprecision (CV) was 6–11% for κ and λ free-light-chain measurement and 16% for the calculated κ/λ ratio. Biological variation was generally insignificant compared with analytical variation. Despite the same reagent source, values were not completely harmonized between assay systems and may produce discordant free-light-chain ratios. In some patients with clinically stable myeloma, or post transplantation, or with monoclonal gammopathy of undetermined significance, free-light-chain concentration and ratio were within the population reference interval despite the presence of monoclonal intact immunoglobulin in serum. In other patients with monoclonal gammopathy of undetermined significance, values were abnormal although there was no clinical evidence of progression to multiple myeloma.

Conclusions: The use of free-light-chain measurements alone cannot differentiate some groups of patients with monoclonal gammopathy from healthy individuals. As with the introduction of any new test, it is essential that more scientific data about use of this assay in different subject groups are available so that results can be interpreted with clinical certainty.
Preanalytic and Analytic Sources of Variations in C-reactive Protein Measurement: Implications for Cardiovascular Disease Risk Assessment
Authors: Ledue Thomas B , Rifai Nader
Published: February 2004

Background: C-reactive protein (CRP) is a widely recognized indicator of inflammation and is known to play an important role in atherogenesis. Recent prospective studies have demonstrated that increased CRP concentrations within the reference interval are a strong predictor of myocardial infarction, stroke, sudden cardiac death, and peripheral vascular disease in apparently healthy adults. On the basis of available evidence, the American Heart Association and the CDC have issued guidelines for the utility of CRP in the primary prevention of coronary heart disease and in patients with stable coronary disease or acute coronary syndromes. Nevertheless, there remains considerable work to optimize the utility of this marker for risk assessment.

Issues: Most traditional CRP tests designed to monitor acute and chronic inflammation have inadequate sensitivity for risk stratification of coronary disease. Thus, manufacturers have had to develop tests with higher sensitivity. Because an individual’s CRP concentration will be interpreted according to fixed cut-points, issues related to the preanalytic and analytic components of CRP measurement must be considered and standardized where possible to avoid potential misclassification of cardiovascular risk.

Conclusions: Efforts to define performance criteria for high-sensitivity CRP applications coupled with growing awareness of the physiologic aspects of CRP most likely will lead to refinements in standardization, improved performance in quality-assessment schemes, and enhanced risk prediction.
Time Course of Early and Late Changes in Plasma DNA in Trauma Patients
Authors: Lam Nicole Y L , Rainer Timothy H , Chan Lisa Y S , Joynt Gavin M , Lo Y M Dennis
Published: February 2004

Background: Cell-free DNA concentrations increase in the circulation of patients after trauma and may have prognostic potential, but little is know concerning the temporal changes or clearance of the DNA or its relationships with posttraumatic complications. We investigated temporal changes in plasma DNA concentrations in patients after trauma with use of real-time quantitative PCR.

Methods: Serial plasma samples were taken from two trauma populations. In the first study, samples were collected every 20 min from 25 patients within the first 3 h of trauma. In the second study, samples were collected every day from 36 other trauma patients admitted to the intensive care unit (ICU).

Results: In the first study, plasma DNA was increased within 20 min of injury and was significantly higher in patients with severe injury and in patients who went on to develop organ failure. In patients with less severe injuries, plasma DNA concentrations decreased toward reference values within 3 h. In the second study, plasma DNA concentrations were higher in patients who developed multiple organ dysfunction syndrome between the second and fourth days of admission than in patients who did not develop the syndrome. In patients who remained in the ICU with continuing organ dysfunction, plasma DNA remained higher than in healthy controls even at 28 days after injury. Most survivors with multiple organ dysfunction syndrome showed an initial very high peak followed by a prolonged smaller increase.

Conclusions: Plasma DNA concentrations increase early after injury and are higher in patients with severe injuries and in those who develop organ failure. Increased plasma DNA persists for days after injuries, especially in patients with multiple organ dysfunction syndrome.
Increased Homocysteine and S-Adenosylhomocysteine Concentrations and DNA Hypomethylation in Vascular Disease
Authors: Castro Rita , Rivera Isabel , Struys Eduard A , Jansen Erwin E W , Ravasco Paula , Camilo Maria Ermelinda , Blom Henk J , Jakobs Cornelis , Tavares de Almeida Isabel
Published: February 2004

Background: The pathogenic mechanism of homocysteine’s effect on cardiovascular risk is poorly understood. Recent studies show that DNA hypomethylation induced by increases in S-adenosylhomocysteine (AdoHcy), an intermediate of Hcy metabolism and a potent inhibitor of methyltransferases, may be involved in homocysteine-related pathology.

Methods: We measured fasting plasma total Hcy (tHcy), AdoHcy, and S-adenosylmethionine (AdoMet) and methylation in leukocytes in 17 patients with vascular disease and in 15 healthy, age- and sex-matched controls.

Results: Patient with vascular disease had significantly higher plasma tHcy and AdoHcy concentrations and significantly lower plasma AdoMet/AdoHcy ratios and genomic DNA methylation. AdoMet concentrations were not significantly different between the two groups. More than 50% of the patients fell into the highest quartiles of plasma tHcy, AdoHcy, and [3H]dCTP incorporation/μg of DNA (meaning the lowest quartile of DNA methylation status) and into the lowest quartile of the AdoMet/AdoHcy ratios of the control group. Plasma tHcy was significantly correlated with plasma AdoHcy and AdoMet/AdoHcy ratios (n = 32; P < 0.001). DNA methylation status was significantly correlated with plasma tHcy and AdoHcy (n = 32; P < 0.01) but not with plasma AdoMet/AdoHcy ratios.

Conclusion: Global DNA methylation may be altered in vascular disease, with a concomitant increase in plasma tHcy and AdoHcy.
Butyrylcholinesterase (BCHE) Genotyping for Post-Succinylcholine Apnea in an Australian Population
Authors: Yen Tina , Nightingale Brian N , Burns Jennifer C , Sullivan David R , Stewart Peter M
Published: February 2004

Background: Measurement of plasma butyrylcholinesterase (BChE) activity and inhibitor-based phenotyping are standard methods for identifying patients who experience post-succinylcholine (SC) apnea attributable to inherited variants of the BChE enzyme. Our aim was to develop PCR-based assays for BCHE mutation detection and implement them for routine diagnostic use at a university teaching hospital.

Methods: Between 1999 and 2002, we genotyped 65 patients referred after prolonged post-SC apnea. Five BCHE gene mutations were analyzed. Competitive oligo-priming (COP)-PCR was used for flu-1, flu-2, and K-variant and direct DNA sequencing analysis for dibucaine and sil-1 mutations. Additional DNA sequencing of BCHE coding regions was provided when the five-mutation screen was negative or mutation findings were inconsistent with enzyme activity.

Results: Genotyping identified 52 patients with primary hypocholinesterasemia attributable to BCHE mutations, and in 44 individuals the abnormalities were detected by the five-mutation screen (detection rate, 85%). Additional sequencing studies revealed mutations in eight other patients, including five with novel mutations. The most common genotype abnormality was compound homozygous dibucaine and homozygous K-variant mutations. No simple homozygotes were found. Of the remaining 13 patients, 3 had normal BChE activity and gene, and 10 were diagnosed with hypocholinesterasemia unrelated to BCHE gene abnormalities.

Conclusion: A five-mutation screen for investigation of post-SC apnea identified BCHE gene abnormalities for 80% of a referral population. Six new BCHE mutations were identified by sequencing studies of 16 additional patients.
Plasma 99th Percentile Reference Limits for Cardiac Troponin and Creatine Kinase MB Mass for Use with European Society of Cardiology/American College of Cardiology Consensus Recommendations
Authors: Apple Fred S , Quist Heidi E , Doyle Patrick J , Otto Angela P , Murakami MaryAnn M
Published: February 2004

Background: The European Society of Cardiology/American College of Cardiology (ESC/ACC) consensus document for definition of myocardial infarction (MI) is predicated on increased cardiac troponin or creatine kinase (CK) MB mass above the 99th percentile reference limit. The purpose of this study was to determine the plasma (heparin) 99th percentile reference limits for the leading in vitro diagnostic cardiac troponin and CKMB mass assays.

Methods: Blood (heparin plasma) was obtained from healthy adults (n = 696; age range, 18–84 years) stratified by gender and ethnicity. Cardiac troponin I (cTnI) and T (cTnT) and CKMB mass concentrations were measured by eight assays. Reference limits were determined by nonparametric statistical analysis.

Results: Two cTnI assays demonstrated at least a 1.2- to 2.5-fold higher 99th percentile for males vs females, with the mean concentrations significantly higher for males (P <0.05). Two cTnI assays also demonstrated a 1.1- to 2.8-fold higher 99th percentile for blacks vs Caucasians, with the mean concentrations significantly higher for blacks (P = 0.05). There was a 13-fold variance between the lowest measured 99th percentile (0.06 μg/L) and the highest (0.8 μg/L). All CKMB assays demonstrated a 1.2- to 2.6-fold higher 99th percentile for males vs females, with mean concentrations significantly higher for males (P <0.0001). Four CKMB assays also showed significantly higher (1.2- to 2.7-fold) mean concentrations for blacks (P <0.02) vs Caucasians.

Conclusions: The heparin-plasma 99th percentile reference limits for cardiac troponin and CKMB mass provide an evidence base in support of the ESC, ACC, and American Heart Association guidelines for detection of myocardial injury. Selective gender and ethnic differences were demonstrated. These data allow clinicians, trialists, and epidemiologists a common point for operational use.
Utility of the Amino-Terminal Fragment of Pro-Brain Natriuretic Peptide in Plasma for the Evaluation of Cardiac Dysfunction in Elderly Patients in Primary Health Care
Authors: Alehagen Urban , Lindstedt Göran , Eriksson Henry , Dahlström Ulf
Published: February 2004

Background: The aims of this study were to measure the N-terminal fragment of pro-brain natriuretic peptide (proBNP) in plasma in medical conditions commonly found in primary care and to evaluate the utility of these measurements in identifying impaired cardiac function in elderly patients with symptoms associated with heart failure.

Methods: We studied 415 patients (221 men and 194 women; mean age, 72 years) who had contacted a primary healthcare center for dyspnea, fatigue, and/or peripheral edema. One cardiologist evaluated the patients in terms of history, physical examination, functional capacity, electrocardiography, and suspicion of heart failure. Plasma N-terminal proBNP was measured by an in-house RIA. An ejection fraction ≤40% by Doppler echocardiography was regarded as reduced cardiac function. Abnormal diastolic function was defined as an abnormal mitral inflow defined as reduced ratio of peak early diastolic filling velocity to peak filling velocity at atrial contraction (E/A ratio), or as abnormal pulmonary venous flow pattern.

Results: Patients with impaired functional capacity, impaired systolic function, and/or impaired renal function had significantly increased N-terminal proBNP concentrations. By multiple regression analysis, N-terminal proBNP concentrations were also influenced by ischemic heart disease, cardiac enlargement, and certain medications but not by increased creatinine. No gender differences were observed. Patients with isolated diastolic dysfunction attributable to relaxation abnormali-ties had lower concentrations than those with normal cardiac function, whereas those with pseudonormal E/A ratios or restrictive filling patterns had higher concentrations.

Conclusions: Plasma N-terminal proBNP concentrations increase as a result of impaired systolic function, age, impaired renal function, cardiac ischemia and enlargement, and certain medications. Values are high in diastolic dysfunction with pseudonormal patterns, but not in patients with relaxation abnormalities. An increase in plasma N-terminal proBNP might be an earlier sign of abnormal cardiac function than abnormalities identified by currently used echocardiographic measurements.
Xuezhikang Decreases Serum Lipoprotein(a) and C-reactive Protein Concentrations in Patients with Coronary Heart Disease
Authors: Liu Ling , Zhao Shui-Ping , Cheng Yan-Chun , Li Yu-Ling
Published: February 2004

Background: Increased serum lipoprotein(a) [Lp(a)] and high-sensitivity C-reactive protein (hsCRP) concentrations are independent risk factors for coronary heart disease (CHD). Xuezhikang, an extract of cholestin, effectively lowers fasting cholesterol and triglyceride concentrations. We studied whether xuezhikang lowered Lp(a) and hsCRP concentrations.

Methods: We randomly divided 60 CHD patients into two groups to receive xuezhikang (1200 mg daily) or placebo for 6 weeks. The fasting hsCRP concentration and the postprandial changes of serum lipid concentrations at 2, 4, and 6 h after a high-fat meal (800 calories; 50 g of fat) were measured before and after the 6-week protocol.

Results: The two groups had similar baseline fasting lipid and hsCRP concentrations. The postprandial triglyceride and Lp(a) concentrations were significantly increased (P <0.05). After 6 weeks, the fasting and postprandial lipid concentrations decreased significantly in the xuezhikang group, accompanied by a significant reduction in fasting hsCRP concentration (P <0.001). The placebo group had no significant change in lipid concentrations, whereas the fasting serum hsCRP concentration was reduced significantly (P <0.05). The reduction in hsCRP was closely related to the changes in fasting Lp(a) concentration (r = 0.402; P <0.05) and triglyceride area under the curve (r = 0.441; P <0.001).

Conclusions: Xuezhikang effectively decreased fasting Lp(a) and postprandial triglyceride concentrations, which were associated with reductions of fasting hsCRP concentrations in CHD patients.
γ-Glutamyltransferase Is a Predictor of Incident Diabetes and Hypertension: The Coronary Artery Risk Development in Young Adults (CARDIA) Study
Authors: Lee Duk-Hee , Jacobs David R , Gross Myron , Kiefe Catarina I , Roseman Jeffrey , Lewis Cora E , Steffes Michael
Published: February 2004

Background: γ-Glutamyltransferase (GGT), which maintains cellular concentrations of glutathione, may be a marker of oxidative stress, and GGT itself may produce oxidative stress. We performed a prospective study to examine whether serum GGT predicts diabetes and hypertension.

Methods: Study participants were 4844 black and white men and women 18–30 years of age in 1985–1986; they were reexamined 2, 5, 7, 10, and 15 years later. Year 0 GGT cutpoints were 12, 17, 25, and 36 U/L (overall 25th, 50th, 75th, and 90th percentiles; the laboratory cutpoints for abnormal are 40 U/L in women and 50 U/L in men). We deleted 32 participants with prevalent diabetes and 140 participants with prevalent hypertension from the respective incidence analyses.

Results: After adjustment for study center, race, sex, and age in proportional hazards regression, the hazard ratios across year 0 GGT categories were 1.0, 1.6, 1.7, 4.0 (95% confidence interval, 2.0–8.1), and 5.5 (2.7–11.1) for 15-year incident diabetes and 1.0, 1.2, 1.7 (1.2–2.2), 2.3 (1.7–3.2), and 2.3 (1.7–3.2) for hypertension. Additional adjustment for year 0 alcohol consumption, body mass index, cigarette smoking, and physical activity attenuated this relationship, but GGT remained a significant predictor.

Conclusions: Serum GGT within a range regarded as physiologically normal is associated with incident diabetes and hypertension. Considering known functionality of GGT, these associations are consistent with a role for oxidative stress in risk for diabetes and hypertension.
Mild Transcobalamin I (Haptocorrin) Deficiency and Low Serum Cobalamin Concentrations
Authors: Carmel Ralph
Published: February 2004

Background: Low cobalamin concentrations are common, but their causes are often unknown. Transcobalamin I/haptocorrin (TC I/HC) deficiency, viewed as a rare cause, has not been examined systematically in patients with unexplained low serum cobalamin.

Methods: Total TC I/HC was measured by RIA in three subgroups of 367, 160, and 38 patients with different categories of low cobalamin concentrations and three comparison subgroups of 112, 281, and 119 individuals with cobalamin concentrations within the reference interval. Additional studies, including family studies, were done in selected patients found to have low TC I/HC concentrations.

Results: Low TC I/HC concentrations suggestive of mild TC I/HC deficiency occurred in 54 of 367 (15%) patients with low cobalamin identified by clinical laboratories and 24 of 160 (15%) patients whose low cobalamin was unexplained after absorption and metabolic evaluation, but in only 2 of 38 patients with malabsorptive causes of low cobalamin concentrations (5%). The prevalence was only 3% (8 of 281 plasma samples) to 5% (6 of 112 sera) in patients with cobalamin concentrations within the reference interval and 3% (4 of 119) in healthy volunteers. Three patients with low cobalamin (0.6%) had severe TC I/HC deficiency with undetectable TC I/HC. Presumptive heterozygotes for severe TC I/HC deficiency in two families had the findings of mild TC I/HC deficiency; mild deficiency was also found in at least three of seven studied families of patients with mild TC I/HC deficiency.

Conclusions: Mild TC I/HC deficiency is frequently associated with low cobalamin, is often familial, and its biochemical phenotype appears identical to the heterozygous state of severe TC I/HC deficiency. Severe TC I/HC deficiency also appears to be more common than suspected. Both diagnoses should be considered in all patients with unexplained low serum cobalamin.
Testosterone Measured by 10 Immunoassays and by Isotope-Dilution Gas Chromatography–Mass Spectrometry in Sera from 116 Men, Women, and Children
Authors: Taieb Joëlle , Mathian Bruno , Millot Françoise , Patricot Marie-Claude , Mathieu Elisabeth , Queyrel Nicole , Lacroix Isabelle , Somma-Delpero Claude , Boudou Philippe
Published: February 2004

Background: Commercially available testosterone immunoassays give divergent results, especially at the low concentrations seen in women. We compared immunoassays and a nonimmunochemical method that could quantify low testosterone concentrations.

Methods: We measured serum testosterone in 50 men, 55 women, and 11 children with use of eight nonisotopic immunoassays, two isotopic immunoassays, and isotope-dilution gas chromatography–mass spectrometry (ID/GC-MS).

Results: Compared with ID/GC-MS, 7 of the 10 immunoassays tested overestimated testosterone concentrations in samples from women; mean immunoassay results were 46% above those obtained by ID/GC-MS. The immunoassays underestimated testosterone concentrations in samples from men, giving mean results 12% below those obtained by ID/GC-MS. In women, at concentrations of 0.6–7.2 nmol/L, 3 of the 10 immunoassays gave positive mean differences >2.0 nmol/L (range, −0.7 to 3.3 nmol/L) compared with ID/GC-MS; in men at concentrations of 8.2–58 nmol/L, 3 of the 10 immunoassays tested gave mean differences >4.0 nmol/L (range, −4.8 to 2.6 nmol/L).

Conclusion: None of the immunoassays tested was sufficiently reliable for the investigation of sera from children and women, in whom very low (0.17 nmol/L) and low (<1.7 nmol/L) testosterone concentrations are expected.
Indications for Requesting Laboratory Tests for Concurrent Diseases in Patients with Carpal Tunnel Syndrome: A Systematic Review
Authors: van Dijk Mariska A J , Reitsma Johannes B , Fischer Johan C , Sanders Gerard T B
Published: February 2004

Background: Carpal tunnel syndrome (CTS) is known as a repetitive motion disorder, but the role of other diseases in the development or prognosis of CTS is uncertain. We reviewed the literature to determine whether there is evidence for an increased prevalence of specific conditions in CTS patients and whether this evidence would support laboratory screening for these conditions.

Methods: Medline, Embase, and Cochrane Controlled Trial Register were searched for key words related to CTS and associated diseases. Relevant articles were selected according to specific criteria. Sources of bias and heterogeneity attributable to differences in study design and in patient selection were investigated by subgroup analysis.

Results: After an initial search, we limited ourselves to three potentially important conditions: diabetes mellitus (DM), hypothyroidism (HT), and rheumatoid arthritis (RA). We identified nine articles with a total of 4908 CTS patients and 7671 controls that met our selection criteria. The nine studies were heterogeneous with respect to clinical and methodologic factors. In general, the prevalence of concurrent diseases was higher in CTS patients than in controls: the pooled odds ratios were 2.2 (95% confidence interval, 1.5–3.1) for DM, 1.4 (1.0–2.0) for HT, and 2.2 (1.4–3.4) for RA. Studies of lower methodologic quality reported, on average, higher odds ratios. Only one study provided information about whether the diagnosis of the concurrent condition was already made at the time of the CTS diagnosis.

Conclusions: We found evidence that the prevalences of DM, HT, and RA are higher in CTS patients, but only one study specifically addressed the issue of the prevalence of nonmanifest cases of the concurrent condition. At present, there is insufficient evidence for routine laboratory screening for concurrent conditions in all newly diagnosed CTS patients.
Detection of Chromosome 21-encoded mRNA of Placental Origin in Maternal Plasma
Authors: Oudejans Cees B M , Go Attie T J J , Visser Allerdien , Mulders Monique A M , Westerman Bart A , Blankenstein Marinus A , van Vugt John M G
Published: February 2004

Background: mRNA of placental origin (i.e., human placental lactogen and β-human chorionic gonadotropin) has been demonstrated to be easily detectable in maternal plasma. We tested whether detection of chromosome 21-encoded mRNA of placental origin is possible in maternal plasma obtained during the first trimester.

Methods: Plasma samples were obtained from pregnant women between weeks 9–13 of pregnancy. RNA was isolated from 800 or 1600 μL of plasma by silica-based affinity isolation and, after on-column DNase treatment, was subjected to two-step, one-tube reverse transcription-PCR with gene specific primers.

Results: Three chromosome 21-encoded genes located within the Down syndrome critical region with overexpression in trisomy 21 placentas were screened for expression in early placental tissue to select their potential use for RNA based plasma screening. One of the chromosome 21-encoded genes (LOC90625) showed strong expression in first trimester placenta similar to CSH1 (human placental lactogen) and was selected for plasma analysis. The RNA isolation assay was validated with CSH1 mRNA, which could be detected in the plasma of all women tested in weeks 9–13 of pregnancy. RNA from the chromosome 21-encoded, placentally expressed gene, LOC90625, was present in maternal first-trimester plasma and could be detected in 60% of maternal plasma samples when 800 μL of plasma was used and in 100% of samples when 1600 μL of plasma was used.

Conclusion: The detection of chromosome 21-encoded mRNA of placental origin in maternal plasma during the first trimester may allow development of plasma-RNA-based strategies for prenatal prediction of Down syndrome. LOC90625 is a candidate gene for this purpose.
Prognostic Value of Multiple Reverse Transcription-PCR Tyrosinase Testing for Circulating Neoplastic Cells in Malignant Melanoma
Authors: Szenajch Jolanta , Jasiński Bogdan , Synowiec Agnieszka , Kulik Jadwiga , Chomicka Małgorzata , Strużyna Jerzy , Nowecki Zbigniew , Rutkowski Piotr , Ruka Włodzimierz , Kupść Witold , Siedlecki Janusz A , Wiktor-Jȩdrzejczak Wiesław
Published: February 2004

Background: The reverse transcription-PCR tyrosinase assay (TYR test) cannot reliably detect malignant melanoma (MM) cells in blood as the cells often circulate at low concentrations. We evaluated the prognostic value of multiple TYR testing, the prognostic significance of individual positive TYR test results (TYR+) in asymptomatic melanoma patients, and whether statistical analysis could help in the interpretation of results of a test that measures phenomena that typically occur below its detection threshold.

Methods: MM patients in stages I-IV (n = 150) underwent multiple testing with the TYR test during the course of their disease. TYR testing was performed as described by Smith et al. (Lancet 1991;38:1227–9). Statistical analyses were performed with the logistic function and t-test procedures.

Results: The relationship between MM stage and the frequency of TYR+ was statistically significant (P = 0.011). Higher frequency of TYR+ in clinically asymptomatic patients after complete resection of the primary tumor was associated with an increased risk of recurrence of MM (prognostic sensitivity, 62%; specificity, 78%).

Conclusions: A single positive TYR test provides a warning for disease relapse, suggesting that multiple TYR testing might provide more reliable predictions of disease progression. Multiple testing and statistical analysis using a logistic function might allow for the interpretation of apparently inconsistent results of tests for very rare cells.
Development and Assessment of a Quantitative Reverse Transcription-PCR Assay for Simultaneous Measurement of Four Amplicons
Authors: Grace Marcy B , McLeland Christopher B , Gagliardi Steven J , Smith Jeffrey M , Jackson William E , Blakely William F
Published: February 2004

Background: High-throughput and forward-deployable biological dosimetry capabilities are required for tactical and medical decisions after radiologic events. We previously reported a quantitative reverse transcription (QRT)-PCR assay for human radiation-responsive gene targets using a whole-blood ex vivo irradiation model, but we needed a multitarget assay on a smaller, less costly, real-time PCR detection system.

Methods: We developed a quadruplex QRT-PCR assay in a 96-well, closed-plate format suitable for use with RNA extracted from whole blood. Four cDNA targets were simultaneously amplified in a sealed tube by hybridization to exonuclease probes, each conjugated to distinct fluorogenic reporters. A novel primer-limited 18S rRNA reference target was validated from serial dilutions of human total RNA. To test assay precision, we incorporated a positive-control cDNA mimic into duplex and quadruplex PCR reactions. The master mixture was supplemented with more enzyme, MgCl2, and deoxyribonucleotides. Simultaneous detection of four targets was evaluated in comparison with respective duplex QRT-PCR assays.

Results: The simultaneous detection of three radiation-responsive genes by quadruplex QRT-PCR was quantitative, with gene expression changes similar to those observed with optimized duplex and triplex QRT-PCR assays. The 18S rRNA and GADD45 calibration curves (threshold cycle vs log10 cDNA) were linear and reproducible and showed optimal PCR efficiencies as indicated by slopes statistically equivalent to the theoretical value of −3.322.

Conclusions: This is the first study of a quadruplex QRT-PCR assay. Our approach has diagnostic utility in the detection of biomarkers, biological and toxicologic agents, and genes of inherited diseases and cancer.
Unexpected Relationship between Plasma Homocysteine and Intrauterine Growth Restriction
Authors: Infante-Rivard Claire , Rivard Georges-Etienne , Gauthier Robert , Théorêt Yves
Published: February 2004

Background: Moderate hyperhomocysteinemia is considered a risk factor for thrombosis and atherosclerosis. We hypothesized that higher maternal and newborn homocysteine concentrations in plasma would increase the risk of intrauterine growth restriction through placental thrombosis.

Methods: We carried out a case-control study that included all cases born at our institution over a 2-year period whose birthweight was below the 10th percentiles for gestational age and sex according to Canadian norms; controls were born at the same period and institution at or above the 10th percentiles and were matched on gestational age, race, and sex. Homocysteine was measured in cord and maternal blood. The analysis included 483 case and 468 control mothers and 409 case and 438 control newborns.

Results: Homocysteine values were largely <15 μmol/L. Contrary to expectation, within that range of values, increased plasma homocysteine, particularly in the mother, was protective against intrauterine growth restriction. With the case/control status as the outcome, the estimated odds ratio was 0.37 (95% confidence interval, 0.24–0.58) for a 5 μmol/L unit difference on the maternal homocysteine scale. With birthweight as the outcome, the estimated increase was 178.1 g (95% confidence interval, 92.5–263.7 g) for every 5 μmol/L unit increase in maternal homocysteine. Results were similar using newborn homocysteine concentrations.

Conclusions: The data suggest that, in contrast to the proposed hypothesis, mothers with small babies have lower homocysteine concentrations than those giving birth to larger ones.
Comparison of Diagnostic Accuracies in Outpatients and Hospitalized Patients of D-Dimer Testing for the Evaluation of Suspected Pulmonary Embolism
Authors: Schrecengost John E , LeGallo Robin D , Boyd James C , Moons Karel G M , Gonias Steven L , Rose C Edward , Bruns David E
Published: February 2004

Background: The ability of various D-dimer assays to exclude the diagnosis of thromboembolic diseases is controversial. We examined the diagnostic accuracy of two D-dimer methods in hospitalized patients and outpatients.

Methods: We studied consecutive patients for whom D-dimer testing was ordered for investigation of suspected pulmonary embolism. We measured D-dimer by an ELISA (VIDAS D-dimer) and an enhanced microlatex immunoassay method (Diagnostica Stago STA Liatest D-di). Patient diagnoses were based on imaging studies or, when these were not performed, on follow-up by review of medical records 3 months later.

Results: We examined 233 hospitalized patients and 234 outpatients with a mean age of 58 years (range, 1–92 years) and a female-to-male ratio of 1.4 to 1. Thromboembolism was present in 8% of outpatients and 12% of hospitalized patients. In outpatients, the negative predictive values were 98% [95% confidence interval (CI), 93–100%] and 99% (94–100%) for the microlatex and ELISA methods, respectively, at the recommended cutoffs. Areas under the ROC curves were similar for the two methods [0.77 (95% CI, 0.67–0.87) and 0.81 (0.73–0.89), respectively]. By contrast, in hospitalized patients, the confidence intervals for the areas under the ROC curves included 0.5 [0.60 (95% CI, 0.50–0.71) and 0.56 (0.44–0.67)].

Conclusions: For hospitalized patients, in contrast to outpatients, the diagnostic accuracy of D-dimer testing for pulmonary embolism is poor in a tertiary care setting, presumably reflecting thrombosis and comorbidities, other than pulmonary embolism, that increase the D-dimer concentrations in these patients. The patient population studied appears more important than assay method in studies of the diagnostic accuracy of D-dimer testing.
Regulation of Serum Paraoxonase Activity by Genetic, Nutritional, and Lifestyle Factors in the General Population
Authors: Ferré Natàlia , Camps Jordi , Fernández-Ballart Joan , Arija Victoria , Murphy Michelle M , Ceruelo Santiago , Biarnés Elisabet , Vilella Elisabet , Tous Mónica , Joven Jorge
Published: February 2004

Background: Paraoxonase may protect lipoproteins and cell membranes from peroxidation, and alterations in the activity of this enzyme have been associated with some chronic diseases. Serum paraoxonase appears to be mainly under genetic control, but some studies suggest that environmental factors may also modulate its activity. The aim of the present study was to investigate whether diet and lifestyle affect serum paraoxonase activity.

Methods: We studied a population-based sample of 388 individuals (194 women and 194 men; age range, 18–75 years) and assessed their daily dietary intake using a 3-day estimated food record. The variables studied included serum paraoxonase activity, paraoxonase polymorphisms at positions 55 and 192, age, gender, smoking status, physical exercise, body mass index, energy consumption, nutrient intake (total lipids, saturated fatty acids, β-carotenes, vitamins C and E), and serum lipid concentrations.

Results: Multiple linear regression analysis showed that only genetic polymorphisms, serum cholesterol, HDL-cholesterol concentrations, and cigarette smoking were significant predictors of serum paraoxonase activity. HDL-cholesterol concentrations were also related to body mass index, daily energy consumption, and saturated fatty acid intake.

Conclusions: The between-individual variability of serum paraoxonase activity is regulated mainly by genetic determinants. Although HDL-cholesterol and tobacco smoking may contribute to the modulation of this enzyme, the other nutritional and lifestyle factors do not seem to play a significant role.
Potential Usefulness of Inflammatory Markers to Monitor Respiratory Functional Impairment in Sarcoidosis
Authors: Rothkrantz-Kos Snježana , van Dieijen-Visser Marja P , Mulder Paul G H , Drent Marjolein
Published: February 2004

Background: Sarcoidosis is a multiorgan inflammatory granulomatous disorder of unknown origin for which adequate markers to monitor disease severity are lacking. The aim of this study was to evaluate the potential clinical usefulness of serologic markers of inflammation [high-sensitivity C-reactive protein (hs-CRP) and serum amyloid A (SAA)], T-cell activation [soluble interleukin-2 receptor (sIL2R)], and granuloma formation [angiotensin-converting enzyme (ACE)] for monitoring of sarcoidosis.

Methods: Of the 185 sarcoidosis patients who visited the Sarcoidosis Management Center between 1999 and 2002, we selected 144 nonsmoking patients: 73 untreated (group I) and 71 treated (group II). Subgroups of the untreated patients [group Ia (nonchronic group with time since diagnosis ≤2 years) and group Ib (chronic group with time since diagnosis >2 years)] were evaluated separately. ROC curves and logistic regression analyses were used to compare the diagnostic accuracy of different markers to assess disease severity. Pulmonary disease severity was defined by lung function test results.

Results: In untreated subgroup Ia and the total untreated group (group I), sIL2R had the largest areas under the curves (AUCs; 0.891 and 0.799, respectively) and the highest sensitivity (82% and 64%), specificity (94% and 88%), and positive (82% and 70%) and negative (94% and 88%) predictive values among the evaluated markers in both untreated groups. Nevertheless, the confidence intervals for sIL2R AUC, sensitivity, and specificity were broad and partly overlapped those of ACE, hs-CRP, and SAA. In the treated group (group II), all four markers appeared to have comparable AUCs, ranging from 0.645 for SAA to 0.711 for sIL2R.

Conclusion: sIL2R appears to be useful for monitoring respiratory disease severity in sarcoidosis. We recommend sIL2R measurement in the follow-up of patients with sarcoidosis.
Grundausbildung in der Automatisierungstechnik (Basic Courses in Automatic Control)
Authors: Litz Lothar , Lunze Jan
Published: February 2004

Dieser Beitrag greift die Frage nach dem Inhalt von Einführungsvorlesungen in das Gebiet der Automatisierungstechnik auf und plädiert für eine Verbreiterung des behandelten Stoffes. An zwei in den letzten Jahren neu eingeführten Lehrveranstaltungen wird gezeigt, wie man diese Forderung mit modernen Lehrkonzepten erfüllen kann.
Rapid Control Prototyping in der Lehre (Rapid Control Prototyping in Education)
Authors: Schloßer Axel , Bollig Alexander , Abel Dirk
Published: February 2004

Die Regelungs-, Steuerungs- und Automatisierungstechnik ist als fachübergreifende und methodenorientierte Disziplin im Bereich der Ingenieursausbildung fest etabliert. Gerade diese positiven Eigenschaften bedingen jedoch auch eine starke mathematische Ausrichtung der Grundlagenausbildung, der häufig weitere eher theoretische Vertiefungsvorlesungen folgen. Dies führt dazu, dass in vielen Fällen die Vermittlung von Fähigkeiten zur Übertragung der Methoden auf reale Prozesse – speziell das "Engineering" – unterrepräsentiert ist. In diesem Bereich stehen heute jedoch immer leistungsfähigere Rechnerwerkzeuge unterstützend zur Verfügung. Der Beitrag zeigt auf, welche neuen Anforderungen und Möglichkeiten sich aufgrund der zunehmend rechnergestützten Entwurfsprozesse für die Lehrinhalte der Regelungs-, Steuerungs- und Automatisierungstechnik ergeben und wie diese Anforderungen im universitären Umfeld vermittelt werden können.
Integration und Interaktion: Möglichkeiten des Einsatzes von Notebooks und Internet in der regelungstechnischen Lehre (Integration and Interaction: Opportunities of Using Notebooks and Internet for Teaching in Control Engineering)
Authors: Schumm Peter , Bullinger Eric , Schweickhardt Tobias , Allgöwer Frank
Published: February 2004

In Schulen werden bereits seit einigen Jahren Notebooks für den Einsatz in der Lehre erprobt und auch schon erfolgreich eingesetzt. Neu hingegen sind die aktuellen Bestrebungen, Laptops auch in die Hochschul-Ausbildung einzubinden. Der erste Teil dieses Beitrags gibt einen Überblick über das Konzept des BMBF-Projekts Notebook University. Im zweiten Teil wird der konkrete Einsatz von Notebooks für die regelungstechische Ausbildung anhand des Projekts eLearnIng. beschrieben.
Regelungstechnik multimedial, Lernen am PC (Multimedia for Control Theory, PC-based Learning)
Authors: Hoyer Helmut , Gerke Michael , Laaser Wolfram
Published: February 2004

Dieser Beitrag beschreibt einen multimedialen Lernkurs zur Regelungstechnik, so wie sie in Grundlagenvorlesungen an wissenschaftlichen Hochschulen gelehrt wird. Der Lernkurs wird ergänzt durch eine Simulationsumgebung, die zu Übungszwecken und für praktische Anwendungen einsetzbar ist. Dieser multimediale Kurs dient als Unterstützung bei der heimischen Nachbearbeitung von Lerninhalten durch Studierende sowie zur Wiederauffrischung von Wissensinhalten bei bereits berufstätigen Ingenieuren. Daher berücksichtigt er die speziellen Bedürfnisse sowohl der Fernlehre als auch des lebenslangen Lernens. Die auf einer CD-ROM basierende Version dieser Lernumgebung wird hier vorgestellt. Wir berichten von methodischen Aspekten und gewonnenen Erfahrungen während ihrer Erstellung und geben Resultate aus einer studentischen Evaluation wieder.
LEARN2CONTROL – Projektorientiertes Lernen für ein besseres Gesamtverständnis in der regelungstechnischen Ausbildung (LEARN2CONTROL – Project-oriented Learning for a Better Understanding in Control Engineering Education)
Authors: Liefeldt Andreas , Völker Marten , Remelhe Manuel , Dadhe Kai , Engell Sebastian , Fritsch Carsten , Markgraf Norman
Published: February 2004

LEARN2CONTROL ist eine computergestützte Lernumgebung, die es ermöglicht, vorhandenes Grundlagenwissen im Bereich der Regelungstechnik durch selbstständiges Lernen in einem projektorientierten Umfeld zu vertiefen. Der Lernschwerpunkt liegt dabei besonders auf der Vermittlung der inneren Abhängigkeiten und Wechselwirkungen der unterschiedlichen Verfahren und Methoden der Regelungstechnik.
Ultra-Microelectrode Voltammetric Measurement of the Hydrodynamic Radii and Shear Plane of Micellar Particles for Sodium Dodecyl Sulfate in Aqueous NaCl Solutions
Authors: Yang Zhenyu , Zhao Jinsheng , Xie Yu , Yin Xiuli , Du Zhankui , Yang Zhengyu
Published: February 2004

Ultra-microelectrode voltammetric measurements have been performed on sodium dodecyl sulfate (SDS) in the aqueous NaCl solutions at 298.2 ± 0.1 K. The hydrodynamic radii (R
h
0) of micellar particles are calculated. The results suggest that R
h
0 decrease initially due to collapse of the shear plane toward the micelle hard-sphere surface, and then R
h
0 increase gradually due to electrolyte-induced linear spherical expansion of the micellar particles. Based on it, the location of micellar shear plane, the relationship between the shear plane and Debye–Hückel length, and the associated ζ-potential are also estimated. It is found that the relationship between the shear plane and Debye–Hückel length is linear, and, in different NaCl concentrations, the shear plane is almost located at a constant shear potential of 77 ± 10 mV, close to the hard-sphere surface of SDS micelle particles.
Viscosity Coefficients of NaSCN, KSCN, NH4SCN and MnSO4, CoSO4, NiSO4, CdSO4 in Aqueous Binary Mixtures of N,N-Dimethylformamide at 20 °C
Authors: Tsierkezos Nikos G. , Molinou Ioanna E.
Published: February 2004

Viscosities of sodium, potassium, ammonium thiocyanates and manganese, cobalt, nickel, cadmium sulfates have been measured in water + N,N-dimethylformamide (DMF) mixtures at 20 °C. The experimental data have been analyzed using the Jones–Dole equation and the B coefficients have been calculated. The results have been discussed in terms of ion-solvent and solvent-solvent interactions.