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PubMed1999

[Reference standards for the loneliness scale].

This article focuses on the cutting scores for the measurement of loneliness on the Loneliness Scale. A cutting score is used to distinguish the lonely from the not lonely. Data have been analyzed relating to interviews with 3,823 respondents (54-89 years old) who live independently. Use has been made of the individuals' self-assessed level of loneliness. More than would be the case with arbitrary cutting scores, this is in keeping with the individuals' own perception. The figures show that 68% of the elderly persons in the Netherlands are not lonely, 28% are moderately lonely, and 4% are quite lonely. Previous research used a lower cutting score and, consequently, observed that much more people are lonely.

Aged↗
PubMed1988

Production of a proposed international reference standard Alternaria extract. II. Results of a collaborative trial.

A lyophilized Alternaria extract prepared from a defined eight-strain source material was compared with three other Alternaria extracts to assess its potential suitability as an international standard (IS). Twenty-two laboratories in 12 different countries collaborated. Assay methods included RAST inhibition, quantitative immunoelectrophoresis, thin-layer isoelectric focusing, skin testing, leukocyte histamine release, and various other methods for thorough characterization of the extracts. In addition, three laboratories quantitated specific allergen in each extract. The proposed IS extract could be used to assign a relative potency to other test extracts. In separate studies, the proposed IS extract was demonstrated to be stable for at least 21 months when it is stored at -70 degrees C, -20 degrees C, and 4 degrees C.

Alternaria↗
PubMed2006

Rapid quantification methods for genetically modified maize contents using genomic DNAs pretreated by sonication and restriction endonuclease digestion for a capillary-type real-time PCR system with a plasmid reference standard.

For rough quantitative analysis of genetically modified maize contents, rapid methods for measurement of the copy numbers of the cauliflower mosaic virus 35S promoter region (P35S) and MON810 construct-specific gene (MON810) using a combination of a capillary-type real-time PCR system with a plasmid DNA were established. To reduce the characteristic differences between the plasmid DNA and genomic DNA, we showed that pretreatment of the extracted genomic DNA by a combination of sonication and restriction endonuclease digestion before measurement is effective. The accuracy and reproducibility of this method for MON810 content (%) at a level of 5.0% MON810 mixed samples were within a range from 4.26 to 5.11% in the P35S copy number quantification. These methods should prove to be a useful tool to roughly quantify GM maize content.

DNA Restriction Enzymes↗
PubMed2006

Synthesis of reference standards to enable single cell metabolomic studies of tetramethylrhodamine-labeled ganglioside GM1.

Ganglioside GM1 and its seven potential catabolic products: asialo-GM1, GM2, asialo-GM2, GM3, Lac-Cer, Glc-Cer and Cer, were labeled with tetramethylrhodamine (TMR) to permit ultra-sensitive analysis using laser-induced fluorescence (LIF) detection. The preparation involved acylation of the homogenous C(18)lyso-forms of GM1, Lac-Cer, Glc-Cer and Cer with the N-hydroxysuccinimide ester of a beta-alanine-tethered 6-TMR derivative, followed by conversion of these labeled products using galactosidase, sialidase, and sialyltransferase enzymes. The TMR-glycolipid analogs produced are detectable on TLC down to the 1 ng level by the naked eye. All eight compounds could be separated within 4 min in capillary electrophoresis where they could be detected at the zeptomole (ca. 1000 molecule) level using LIF.

Animals↗
PubMed2005

Short tandem repeat DNA typing provides an international reference standard for authentication of human cell lines.

Cell lines have wide applications as model systems in the medical and pharmaceutical industry. Much drug and chemical testing is now first carried out exhaustively on in vitro systems, reducing the need for complicated and invasive animal experiments. The basis for any research, development or production program involving cell lines is the choice of an authentic cell line. Microsatellites in the human genome that harbour short tandem repeat (STR) DNA markers allow individualisation of established cell lines at the DNA level. Fluorescence polymerase chain reaction amplification of eight highly polymorphic microsatellite STR loci plus gender determination was found to be the best tool to screen the uniqueness of DNA profiles in a fingerprint database. Our results demonstrate that cross-contamination and misidentification remain chronic problems in the use of human continuous cell lines. The combination of rapidly generated DNA types based on single-locus STR and their authentication or individualisation by screening the fingerprint database constitutes a highly reliable and robust method for the identification and verification of cell lines.

Animal Testing Alternatives↗
PubMed2005

A study of glycoproteins in human serum and plasma reference standards (HUPO) using multilectin affinity chromatography coupled with RPLC-MS/MS.

The glycoproteome is a major subproteome present in human plasma. In this study, we isolated and characterized approximately 150 glycoproteins from the human plasma and serum samples provided by HUPO using a multilectin affinity column. The corresponding tryptic digest was separated by RP-HPLC coupled to an IT mass spectrometer (3-D LCQ). Also in this study, a new system, namely an Ettan MDLC system coupled to a linear ITLTQ, was compared with the previous LCQ platform and gave a greater number of protein identifications, as well as better quality. When we compared the composition of the glycoproteomes for the plasma and serum samples there was a close correlation between the samples, except for the absence of fibrinogen from the identified-protein list in the latter sample, which was presumably as a result of the clotting process. In addition, the analysis of the samples from three ethnic specimens, Caucasian American, Asian American, and African American, were very similar but showed a higher angiotensinogen plasma level and a lower histidine-rich glycoprotein level in Caucasian American samples, and a lower vitronectin level in African American blood samples.

Blood Proteins↗
PubMed1986

Modification of the chemical composition and structure of the U.S. Reference Standard Endotoxin (RSE) by 60Co radiation.

A highly purified bacterial lipopolysaccharide (LPS) preparation was exposed in water to megadoses of ionizing radiation from a 60Co source. As evidenced by electrophoresis, the radiation treatment progressively degraded the lipopolysaccharide molecules by removing first the O-side chain units and then components of the R-core. Chemical analysis of the irradiated (LPS) preparations showed that, in accord with the structural changes, the most profound effects of ionizing radiation occurred in the hydrophilic oligo/polysaccharide moieties (R-core and O-side chain). Progressively higher doses of radiation degraded the simple sugars in decreasing order of galactose, galactosamine, glucosamine, glucose, and heptose. The R-core component 2-keto-3-deoxyoctonate was the most "resistant" sugar derivative to ionizing radiation. Due to its central position in the LPS aggregates in water, even at comparatively high doses of radiation the hydrophobic lipid A moiety of endotoxin was less affected than the sugar components. Of the fatty acids of lipid A, however, either partial conversion of beta-hydroxymyristic acid into myristic acid or selective loss of the former occurred. The observed structural and chemical changes of LPS are consistent with the effect of active oxygen radicals of radiolysis. In addition, the extensive physicochemical changes explain the altered biological reactivity of radiation-treated endotoxins.

Cobalt Radioisotopes↗
PubMed1998

Accuracy of a portable International Normalization Ratio monitor in outpatients receiving long-term oral anticoagulant therapy: comparison with a laboratory reference standard using clinically relevant criteria for agreement.

The accuracy of a new, portable INR monitor (CoaguChek, Boehringer-Mannheim, Indianapolis, IN) was evaluated by comparing INR results from the portable monitor with results obtained by a laboratory-based method. Dual INR measurements (portable monitor, laboratory) were performed in 163 consecutive outpatients receiving warfarin. Agreement in dual INR measurements was defined based on clinically-relevant expanded and narrow criteria and statistical criteria. Agreement in dual INR measurements also was evaluated as a function of increasing INR. The proportion of dual INR measurements that satisfied the clinically-relevant expanded, and narrow agreement criteria was 90%, and 86%, respectively. Seventy-nine percent of all dual measurements were within 0.5 INR units. The accuracy of the portable monitor was greatest for INR values less than 3.0; above this INR level, the portable monitor underestimated laboratory INR values. The proportion of dual INR measurements within 0.5 INR units for laboratory INR ranges of <2.0, 2.0-3.0, 3.1-4.0, and >4.0 was 98%, 87%, 57%, and 21%, respectively. We conclude that the portable INR monitor achieved a clinically acceptable level of accuracy when compared to the traditional laboratory method and provides a suitable alternative method of monitoring the INR in patients receiving warfarin.

Administration, Oral↗
PubMed2006

A comparison study of the prevalence of overweight and obese Italian preschool children using different reference standards.

INTRODUCTION: The number of overweight children is constantly increasing in both developed and underdeveloped countries. Most epidemiological surveys consider school age children with little attention being given to preschool age children. This study was undertaken to define the prevalence of being overweight or obese in a population of children 3-6 years of age, living in North-East Italy. We also identified differences when comparing body mass index (BMI) data against three different national and international standards. SUBJECTS AND METHODS: The study involved 258 children (124 males and 134 females) with an average age of 4.8 years. Weight and height were obtained for each child and BMI was calculated according to the formula weight (kg)/height (m)(2). The prevalence of overweight and obese subjects was then determined using the growth curves of the Centers for Disease Control and Prevention (CDC), the growth curves of the International Obesity Task Force (IOTF) and the curves published in 2003 by Luciano et al. RESULTS: All three methods gave similar, but not identical, estimates of the prevalence of overweight in both boys and girls. However, when determining the prevalence of obesity, the use of the CDC curves led to a significantly higher prevalence of obesity in both males and females when compared to the growth charts of the IOTF and Luciano et al. BACKGROUND: The use of the CDC growth curves leads to an increase in the prevalence of obesity when evaluating children under 5 years of age. The lower cut-off values inherent in the CDC charts, in contrast to the ones proposed by the IOTF, allow for earlier identification of a larger number of subjects with weight problems and therefore provide the potential for earlier intervention.

Body Mass Index↗
PubMed2002

US for detecting renal calculi with nonenhanced CT as a reference standard.

PURPOSE: To determine the sensitivity and specificity of ultrasonography (US) for detecting parenchymal and renal pelvis calculi and to establish the accuracy of US for determining the size and number of calculi. MATERIALS AND METHODS: A total of 123 US and computed tomographic (CT) examinations were compared retrospectively for the presence of renal calculi. The sensitivity of US was determined for individual calculi and at least one calculus per examination. Retrospective findings were compared with the original US interpretation. The sizes of calculi in longest axis were compared on US and CT images, and the US detection of calculi in the left and right kidneys was compared. The use of US for detecting the full extent of calculus burden was evaluated in patients with multiple calculi. RESULTS: US depicted 24 of 101 calculi identified at CT, yielding a sensitivity of 24% and a specificity of 90%. There was no substantial difference for the detection of calculi in the right and left kidneys. The sensitivity of US for any calculi in a patient was 44%, equal to that of the original US interpretation. US enabled identification of 39% of patients with multiple calculi and demonstrated all calculi in 17% of these patients. The mean size of calculi detected with US was 7.1 mm +/- 1.2 (95% CI); 73% of calculi not visualized at US were less than 3.0 mm in size. Calculus size based on US and CT measurements was concordant in 79% of cases and differed by a mean of 1.5 mm +/- 0.7. CONCLUSION: US is of limited value for detecting renal calculi.

Adolescent↗
PubMed2004

Plasma fluorescence scanning and fecal porphyrin analysis for the diagnosis of variegate porphyria: precise determination of sensitivity and specificity with detection of protoporphyrinogen oxidase mutations as a reference standard.

BACKGROUND: Variegate porphyria (VP) is the autosomal dominant disorder associated with deficiency of the enzyme protoporphyrinogen oxidase (PPOX). Plasma fluorescence scanning has been reported to be a more sensitive test for VP than traditional fecal chromatography. Previous comparisons of these techniques predated identification of the PPOX gene. We assessed these techniques in a large group of patients characterized for VP at the DNA level. METHODS: We evaluated all patients for whom the genotype and a plasma scan or fecal porphyrin result were available. Mutations were detected by restriction digest analysis. Plasma fluorescence scanning was conducted according to published methods. Fecal porphyrins were identified and quantified by thin-layer chromatography. RESULTS: Plasma fluorescence scanning was assessed in 679 patients (205 with VP who were carriers of a PPOX mutation, either with disease symptoms or asymptomatic) and fecal analysis in 473 (190 with VP). Sensitivity and specificity of both tests were higher in adults than in children and higher for adults with disease symptoms than for asymptomatic carriers. In a direct comparison in 168 adults (73 with VP), plasma scanning was significantly more sensitive than fecal porphyrin analysis [sensitivity, 0.96 (95% confidence interval, 0.89-0.99) vs 0.77 (0.66-0.85)]. Fecal coproporphyrin [area under the curve, 0.87 (0.83-0.90)] was a better predictor of VP than protoporphyrin [0.80 (0.76-0.84)]. CONCLUSIONS: Plasma scanning is a more sensitive and specific test for VP than fecal porphyrin analysis. Neither test is sensitive in children, and both are less sensitive in asymptomatic carriers than in symptomatic cases. DNA analysis therefore remains the preferred method for the identification of carriers, particularly in children.

Adolescent↗
PubMed1984

Electrocardiographic detection of left ventricular hypertrophy using echocardiographic determination of left ventricular mass as the reference standard. Comparison of standard criteria, computer diagnosis and physician interpretation.

Electrocardiographic findings of left ventricular hypertrophy were compared with echocardiographic left ventricular mass in 148 patients to assess performance of standard electrocardiographic criteria, the IBM Bonner program and physician interpretation. On echocardiography, 43% of the patients had left ventricular hypertrophy (left ventricular mass greater than 215 g). Sokolow-Lyon voltage-(S in V1 + R in V5 or V6) and Romhilt-Estes point score correlated modestly with left ventricular mass (r = 0.40, p less than 0.001 and r = 0.55, p less than 0.001, respectively). Sensitivity of Sokolow-Lyon voltage greater than 3.5 mV for left ventricular hypertrophy was only 22%, but specificity was 93%. Point score for probable left ventricular hypertrophy (greater than or equal to 4 points) had 48% sensitivity and 85% specificity, whereas definite hypertrophy (greater than or equal to 5 points) had 34% sensitivity and 98% specificity. Computer analysis resulted in 45% sensitivity and 83% specificity. Overall diagnostic accuracy of the IBM Bonner program (67%) was better than that of Sokolow-Lyon voltage (62%), but worse than the Romhilt-Estes point score (69% for greater than or equal to 4 points or 70% for greater than or equal to 5 points). Three cardiologists interpreted electrocardiograms independently and in a blinded fashion. Physician sensitivity was 56%, specificity 92% and accuracy 76%. Correlation with left ventricular hypertrophy was good (r = 0.70, p less than 0.001). It is concluded that: 1) computer diagnosis of left ventricular hypertrophy by the IBM Bonner program is no more accurate than diagnosis by Sokolow-Lyon or Romhilt-Estes criteria, and 2) physician recognition of left ventricular hypertrophy is more accurate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1996

Comparison of a spectrophotometric microdilution method with RPMI-2% glucose with the National Committee for Clinical Laboratory Standards reference macrodilution method M27-P for in vitro susceptibility testing of amphotericin B, flucytosine, and fluconazole against Candida albicans.

The National Committee for Clinical Laboratory Standards has proposed a reference broth macrodilution method for in vitro antifungal susceptibility testing of yeasts (the M27-P method). This method is cumbersome and time-consuming and includes MIC endpoint determination by visual and subjective inspection of growth inhibition after 48 h of incubation. An alternative microdilution procedure was compared with the M27-P method for determination of the amphotericin B, flucytosine, and fluconazole susceptibilities of 8 American Type Culture Collection strains (6 of them were quality control or reference strains) and 50 clinical isolates of candida albicans. This microdilution method uses as culture medium RPMI 1640 supplemented with 18 g of glucose per liter (RPMI-2% glucose). Preparation of drugs, basal medium, and inocula was done by following the recommendations of the National Committee for Clinical Laboratory Standards. The MIC endpoint was calculated objectively from the turbidimetric data read at 24 h. Increased growth of C. albicans in RPMI-2% glucose and its spectrophotometric reading allowed for the rapid (24 h) and objective calculation of MIC endpoints compared with previous microdilution methods with standard RPMI 1640. Nevertheless, good agreement was shown between the M27-P method and this microdilution test. The MICs obtained for the quality control or reference strains by the microdilution method were in the ranges published for those strains. For clinical isolates, the percentages of agreement were 100% for amphotericin B and fluconazole and 98.1% for flucytosine. These data suggest that this microdilution method may serve as a less subjective and more rapid alternative to the M27-P method for antifungal susceptibility testing of yeasts.

Amphotericin B↗
PubMed1995

Comparison of two alternative microdilution procedures with the National Committee for Clinical Laboratory Standards reference macrodilution method M27-P for in vitro testing of fluconazole-resistant and -susceptible isolates of Candida albicans.

The National Committee for Clinical Laboratory Standards has proposed a reference broth macrodilution method for in vitro antifungal susceptibility testing of yeasts (the M27-P method). This method is cumbersome and time-consuming and includes MIC endpoint determination by the visual and subjective inspection of growth inhibition after 48 h of incubation. Two alternative microdilution procedures for MIC endpoint determination, a spectrophotometric MIC endpoint test that evaluates 80% growth inhibition by the drug and a colorimetric method with an oxidation-reduction indicator (Alamar Blue), were compared with the M27-P method for fluconazole susceptibility testing of 45 susceptible and resistant isolates of Candida albicans. The spectrophotometric method was performed with RPMI 1640 medium with 2% glucose, and the other two tests were performed with plain RPMI 1640 medium. All tests were incubated at 35 degrees C. Excellent agreement was demonstrated between the M27-P method and both 24-h microdilution tests (97.7%) as well as between the two microdilution tests (95.5%). Also, there was agreement in the detection in vivo of fluconazole resistance by the three methods. These preliminary data indicate that both microdilution methods may serve as less subjective alternatives to the M27-P method for the determination of fluconazole MIC endpoints.

AIDS-Related Opportunistic Infections↗
PubMed1987

Reference standards and the physiologic significance of the pregnant goat (Capra hircus) as a human model in obstetrical research.

1. Amniotic fluid, cerebrospinal fluid, serum, and urine chemistries; respiratory rate and arterial and mixed venous blood gases; heart rate, hematocrit, and cardiac output; and arterial, pulmonary artery, central venous and pulmonary wedge pressures were measured in 20 pregnant adult goats of 19.5-34 kg body weight. 2. Arithmetic means, standard deviations, and coefficients of variation were calculated to develop reference values; in addition, the 95% confidence limits for ranges were established. 3. Comparison of derived data with that from non-pregnant goats shows changes similar to those seen when examining pregnant and non-pregnant humans. 4. These results indicate the pregnant goat is an acceptable model for human obstetrical research.

Animals↗
PubMed1991

Cardiopulmonary reference standards in the pregnant sheep (Ovis aries): a comparative study of ovine and human physiology in obstetrics.

1. Complete blood counts, respiratory rate, tidal volume, arterial and mixed venous blood gases; heart rate, cardiac output, and arterial, pulmonary artery, central venous and pulmonary wedge pressures were determined in 10 pregnant adult sheep of 42.7-65.7 kg body weight. 2. Arithmetic means, standard deviations, and coefficients of variation were calculated to develop reference values; in addition, the 95% confidence limits for ranges were established. 3. Comparison of derived data with that from non-pregnant sheep shows changes similar to those seen when examining pregnant and non-pregnant humans. 4. These results indicate the pregnant sheep is an acceptable model for human obstetrical research.

Animals↗
PubMed1998

Detection of chromosomal gains and losses in comparative genomic hybridization analysis based on standard reference intervals.

Criteria for detection of chromosome aberrations by Comparative Genomic Hybridization (CGH) are not standardized and improvement of this part of the analysis is of paramount importance to the applicability of the technique. The aim of this work was to suggest CGH detection criteria that increase the specificity and sensitivity and at the same time include chromosome regions previously excluded from CGH analysis. We analyzed 33 hybridizations with normal DNA and modified our CGH software in order to use a selection of these normal analyses as a model for interpretation of analyses of unknown samples. This approach was successfully tested on 14 samples with known aberrations.

Chromosome Aberrations↗
PubMed2003

Determination of rare-earth elements in a limestone geological standard reference material by ICP-MS following solvent extraction.

Rare-earth elements in a limestone geological standard (JLs-1) were determined by inductively coupled plasma mass spectroscopy (ICP-MS) using phosphoric acid 2-ethylhexyl ester solvent extraction, which had been established for seawater analysis. First, the limestone sample was divided into two fractions: acetic acid soluble (carbonate fraction) and insoluble (residue). A modification of the method was undertaken to achieve quantitative recovery. With this method most of the REEs in the carbonate fraction were quantitatively recovered, except for the heaviest three REEs (Tm, Tb and Lu). The reason for the poor recoveries of the three elements was investigated, but still remained unclear. The mass-spectroscopic interference of BaO with Eu made an accurate determination of both lighter REEs and Eu at the same time impossible. The precision of this method was better than 20%. The data adopted after analytical consideration were consistent with those previously reported.

Journal Article↗