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At least 253 records · Page 14Linked to original sources
PubMed2005

Use of reverse phase protein microarrays and reference standard development for molecular network analysis of metastatic ovarian carcinoma.

Cancer can be defined as a deregulation or hyperactivity in the ongoing network of intracellular and extracellular signaling events. Reverse phase protein microarray technology may offer a new opportunity to measure and profile these signaling pathways, providing data on post-translational phosphorylation events not obtainable by gene microarray analysis. Treatment of ovarian epithelial carcinoma almost always takes place in a metastatic setting since unfortunately the disease is often not detected until later stages. Thus, in addition to elucidation of the molecular network within a tumor specimen, critical questions are to what extent do signaling changes occur upon metastasis and are there common pathway elements that arise in the metastatic microenvironment. For individualized combinatorial therapy, ideal therapeutic selection based on proteomic mapping of phosphorylation end points may require evaluation of the patient's metastatic tissue. Extending these findings to the bedside will require the development of optimized protocols and reference standards. We have developed a reference standard based on a mixture of phosphorylated peptides to begin to address this challenge.

Carcinoma↗
PubMed2001

[Betamethasone Sodium Phosphate Reference Standard (Control 001) of National Institute of Health Sciences].

The raw material of betamethasone sodium phosphate was examined for the preparation of the "Betamethasone Sodium Phosphate Reference Standard (Control 001)". The analytical data obtained were: melting point, 207.2 degrees C; pH, 8.1; optical rotation, [alpha]D20 = +104.4 degrees; UV spectrum, lambda max of 242 nm and specific absorbance in water at 242 nm = 272.9; IR spectrum, specific absorptions at 3386.9, 1721.7, 1663.3, 1620.4, 1605.0, 1094.3, 985.8, 889.8 cm-1; free phosphoric acid, 0.3%; thin-layer chromatography, one impurity was detected until 200 micrograms; high-performance liquid chromatography, total amount of impurities estimated to be less than 0.5%; water, 9.2%. Based on the above results, the raw material was authorized as the Betamethasone Sodium Phosphate Reference Standard (Control 001) of the National Institute of Health Sciences.

Betamethasone↗
PubMed1983

Purge and trap flame photometric gas chromatography technique for the speciation of trace organotin and organosulfur compounds in a human urine standard reference material (SRM).

Ultratrace levels of organotin species and an organosulfur compound were detected in a National Bureau of Standards (NBS) human urine Standard Reference Material, SRM 2670, and a previously certified urine SRM 2672, using a purge and trap system coupled to a gas chromatograph equipped with a flame photometric detector. samples of the SRM were treated with sodium borohydride to form volatile tin hydrides. Species detected included dimethyltin (1.04 ng/ml), butyltin (0.03 ng/ml), and dimethyl-disulfide (2.73 ng/ml) in the new stock of freeze dried human urine SRM 2670 being prepared for issue by NBS and methyltin (1.0 ng/ml), butyltin (1.5 ng/ml), and inorganic tin (28.1 ng/ml) in the old stock of SRM 2672. This analytical technique should have useful applications in studies that are needed to develop a toxicological data base and monitoring programs for human organotin exposure.

Chromatography, Gas↗
PubMed1983

Standardization of high-resolution flow cytometric DNA analysis by the simultaneous use of chicken and trout red blood cells as internal reference standards.

Determination of nuclear DNA content by flow cytometry requires comparison with a reference standard. The use of external standards such as lymphocytes or granulocytes is time-consuming and inaccurate. Chicken red blood cells (CRBC) have a DNA content of 35% of the human diploid value and have been widely used as internal standard. The ratio calculated on the basis of the peak channel numbers of the standard and the sample and used to indicate the DNA content (DNA ratio) is, however, very sensitive to changes in the zero level adjustment of the flow cytometer. If two internal standards are used the DNA ratio becomes independent of the zero level. Rainbow trout red blood cells (TRBC) have a DNA content of 80% of human diploid cells. A mixture of CRBC and TRBC was prepared and stored in small aliquots at -80 degrees C. This mixture was added to the sample before staining. The day-to-day variation of the DNA ratio obtained by use of the two standards was smaller than that obtained by CRBC alone. The possibility of sex related differences in DNA content of CRBC and TRBC was examined. The results indicated that a new batch of standards should be tested against the old batch to avoid the introduction of a systematic error.

Animals↗
PubMedDate not supplied

An update of the Swedish reference standards for weight, length and head circumference at birth for given gestational age (1977-1981).

An update of the Swedish reference standards for weight, length, and head circumference at birth, for each week of gestational age, is presented. It is based on the total Swedish cohorts of infants born 1977-1981 (n = 475,588). A "healthy population" (79%) was extracted, using prospectively collected data. Weekly (28-42 weeks) grouped data for length and head circumference were well approximated by the normal distribution, but the distributions for birthweight were positively skewed. The original skewed distributions for birthweight were transformed, using the square root, resulting in distributions close to the Gaussian. For smoothing purposes, the weakly values for the mean and the standard deviation were both fitted by a third degree polynomial function. These functions also make possible the calculation of the continuous variable, standard deviation score, for individual newborn infants as well as a comparison of distributions between groups of infants. The reference values and charts presented here have two major advantages over the current Swedish ones: the sample size used is now sufficiently large at the lower gestational ages, so that empirically found variations can be used, and the skewness of the birth weight distribution has been taken into account. The use of the reference standards presented here improves and facilitates evaluation of size deviation at birth.

Birth Weight↗
PubMed2004

Analysis of street drugs in seized material without primary reference standards.

A novel approach was used to analyze street drugs in seized material without primary reference standards. Identification was performed by liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS), essentially based on accurate mass determination using a target library of 735 exact monoisotopic masses. Quantification was carried out by liquid chromatography/chemiluminescence nitrogen detection (LC/CLND) with a single secondary standard (caffeine), utilizing the detector's equimolar response to nitrogen. Sample preparation comprised dilution, first with methanol and further with the LC mobile phase. Altogether 21 seized drug samples were analyzed blind by the present method, and results were compared to accredited reference methods utilizing identification by gas chromatography/mass spectrometry and quantification by gas chromatography or liquid chromatography. The 31 drug findings by LC/TOFMS comprised 19 different drugs-of-abuse, byproducts, and adulterants, including amphetamine and tryptamine designer drugs, with one unresolved pair of compounds having an identical mass. By the reference methods, 27 findings could be confirmed, and among the four unconfirmed findings, only 1 apparent false positive was found. In the quantitative analysis of 11 amphetamine, heroin, and cocaine findings, mean relative difference between the results of LC/CLND and the reference methods was 11% (range 4.2-21%), without any observable bias. Mean relative standard deviation for three parallel LC/CLND results was 6%. Results suggest that the present combination of LC/TOFMS and LC/CLND offers a simple solution for the analysis of scheduled and designer drugs in seized material, independent of the availability of primary reference standards.

Amphetamines↗
PubMed1995

History of NIST's contributions to development of standard reference materials and reference and definitive methods for clinical chemistry.

The issuance of cholesterol as a Standard Reference Material (SRM) in 1967 started the National Institute of Standards and Technology (NIST; then named the National Bureau of Standards) on a major effort to help clinical laboratories establish and improve the quality of measurements they make. NIST now issues three kinds of SRMs for that purpose: analyte samples of certified purity as primary standards, serum samples having certified analyte concentrations as accuracy controls, and materials certified for calibrating instruments. In working with clinical laboratory scientists to establish Reference Methods (RMs) for measuring the analytes, NIST developed Definitive Methods (DMs) to use for evaluating RM accuracy and then used the DMs for assigning analyte values to its SRMs. The development of SRMs and DMs is discussed.

Blood↗
PubMed1992

[Tocopherol reference standard (Control 911) of the National Institute of Hygienic Sciences].

The raw material for tocopherol was tested for preparation of the "Tocopherol Reference Standard (Control 911)". Analytical data obtained were as follows: infrared spectrum, same as Tocopherol Reference Standard (Control 881); absorptivity, E1%1cm (292nm) = 75.5; thin-layer chromatography, no impurities were detected up to 50.0 micrograms; high performance liquid chromatography (HPLC), four impurities were detected; assay, 100.7% by HPLC. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Standard (Control 911).

Chromatography, High Pressure Liquid↗
PubMed1982

Right ventricular apical activation time in children. Reference standards for clinical use.

To differentiate proximal from peripheral right bundle-branch block, several investigators have used the right ventricular apical (RVA) activation time, but there is a lack of reference standards for infants and other children. Using intracardiac electrography, His bundle and RVA electrograms were recorded in 123 children before surgery for various types of congenital cardiac malformations. None had evidence of conduction defects on their surface ECG. The average RVA activation time was 15 +/- 7 msec (+/- SD) linearly increasing with age from infancy to adolescence. The values found in this large population may be useful as reference standards for right bundle-branch conduction times in other infants and children.

Adolescent↗
PubMed1984

Use of a reference standard to improve the accuracy and precision of seven kits for determination of ferritin in serum.

We assessed the accuracy and precision of seven commercial kits for serum ferritin. The concentration of ferritin as determined by these assays for a liver ferritin reference standard, a human heart ferritin standard, and normal sera correlated highly, but the absolute values varied widely. Use of an international reference standard for ferritin to prepare the standard curve greatly diminished the variability, but did not eliminate it. Although the seven kits differed in specificity for various human isoferritins, this did not appear substantially to affect accuracy. Six of the seven kits appeared sufficiently precise for clinical use over a wide range of ferritin concentrations.

Ferritins↗
PubMed1993

Rabbit eye irritation caused by wearing toxic contact lenses and their cytotoxicities: in vivo/in vitro correlation study using standard reference materials.

To clarify the relationship between eye irritancy and cytotoxic potential induced by irritant materials, we made lenses coated with standard reference materials (SRMs) prepared from various amounts of zinc diethyldithiocarbamate (ZDEC) and polyurethane (PU). Zinc diethyldithiocarbamate was classified as a mild irritant by the Draize eye irritation test. When ZDEC-SRM coated contact lenses were applied to rabbit eyes, Draize scores increased in proportion to both the ZDEC and PU concentrations used for coating. Furthermore, correlation with the cytotoxic potential (gamma = -0.93) was better than with lactate dehydrogenase (LDH) activities of tears from rabbit eyes wearing these coated lenses (gamma = 0.78). In conclusion, in vivo eye irritancy induced by wearing lenses could be estimated quantitatively with the cytotoxic potentials using a colony assay. Furthermore, we could compare different sensitivities caused by the same set of SRMs among three different sites of tissue. As a result, the order of sensitivity was eye > muscle >> skin.

3T3 Cells↗
PubMed1989

[Ergocalciferol Reference Standard (Control 871) of National Institute of Hygienic Sciences].

The Ergocalciferol Reference Standard (Control 871) for the Japanese Pharmacopoeia was prepared. The following analytical data were obtained: melting point, 115.9 degrees C; infrared spectrum, same as the Japanese Pharmacopoeia Standard "Ergocalciferol Standard (Control 851)"; absorbance, E1%1cm (265 nm) = 464.8; optical rotation, [alpha]20D = +104.7 degrees; thin-layer chromatography, same as the Japanese Pharmacopoeia Standard; high-performance liquid chromatography, contaminants were not detected; assay, 101.2%. On the basis of those results, this material was authorized as the Japanese Pharmacopoeia Standard (control 871).

Chemical Phenomena↗
PubMed2001

Oral bioavailability of lead and arsenic from a NIST standard reference soil material.

The oral bioavailability of soil contaminants is measured using in vitro or in vivo techniques. Current efforts in our laboratory are focused on the comparisons of in vitro methods for bioavailability estimation with the presently employed in vivo techniques, such as animal models. We present a comparison of two techniques for oral bioavailability estimation: in vitro dissolution and in vivo rat feeding using a standard reference soil. Lead (Pb) and arsenic (As) were chosen because of the range of concentration in this soil as well as the large historical database of bioavailability values for these metals. Metal solubility was measured using a sequential soil extraction in synthetic analogues of human saliva, gastric and intestinal fluids. The soluble metal was defined as the bioaccessible fraction. Oral bioavailability of Pb and As was measured in Sprague Dawley rats by determining metal levels in the major organs and urine, feces, and blood at 1-, 2-, and 3-day time points. Extractions to determine bioaccessibility yielded a gastric component of 76.1% and 69.4% for Pb and As, respectively, and intestinal components were 10.7% and 65.9%. The oral bioavailability of the standard reference soil was 0.7% and 37.8% for Pb and As, respectively. Bioaccessibility was greater than bioavailability for both metals in both gastrointestinal compartments. Although Pb had the highest soil concentration of the selected metals, it was the least bioavailable, while As was highly available in both the in vitro and in vivo method. These types of data allow for an in vitro-in vivo comparison of a soil whose metal concentrations have been certified and validated.

Animals↗
PubMed2006

Improved liquid chromatography methods for the separation and quantification of biotin in NIST standard reference material 3280: multivitamin/multielement tablets.

Two independently developed liquid chromatography (LC) methods for the quantitative determination of biotin in multivitamin/multielement tablets (NIST Standard Reference Material 3280 (SRM 3280)) are described. The methods use distinctly different tablet extraction solvents (methanol vs 1.5% aqueous formic acid) and analyte detection principles (mass spectrometry (MS) versus evaporative light-scattering detection (ELSD)) to ensure quantitative reliability. The use of different extraction and detection procedures allows cross-validation of the methods and enhances confidence in the final quantitative results. Both methods yield highly comparable results for the mean level of biotin (LC/MS = 26.5 mg/kg +/- 0.3 mg/kg (n = 12); LC/ELSD = 24.7 mg/kg +/- 1.7 mg/kg (n = 12)) in SRM 3280, yet the methods differ considerably in their analytical characteristics. The isotope-dilution LC/MS method exhibits excellent linearity from 0.02 ng to 77 ng biotin on-column with a method limit of detection (LOD) and limit of quantification (LOQ) of 0.02 ng (S/N > 3) and 0.06 ng (S/N > 10) biotin on-column, respectively. The LC/ELSD method exhibits good linearity from 155 ng to 9900 ng biotin on-column with a method LOD and LOQ of 155 ng (S/N > 3) and 310 ng (S/N > 10) biotin on-column, respectively. Method performance data indicates that the LC/MS method is analytically superior to the LC/ELSD method; however, either method in combination with SRM 3280 should provide quality assurance, accuracy, and traceability for biotin levels in multivitamin/multielement dietary supplements.

Biotin↗
PubMed2004

Three new mussel tissue standard reference materials (SRMs) for the determination of organic contaminants.

Three new mussel tissue standard reference materials (SRMs) have been developed by the National Institute of Standards and Technology (NIST) for the determination of the concentrations of organic contaminants. The most recently prepared material, SRM 1974b, is a fresh frozen tissue homogenate prepared from mussels ( Mytilus edulis) collected in Boston Harbor, Massachusetts. The other two materials, SRMs 2977 and 2978, are freeze-dried tissue homogenates prepared from mussels collected in Guanabara Bay, Brazil and Raritan Bay, New Jersey, respectively. All three new mussel tissue SRMs complement the current suite of marine natural-matrix SRMs available from NIST that are characterized for a wide range of contaminants (organic and inorganic). SRM 1974b has been developed to replace its predecessor SRM 1974a, Organics in Mussel Tissue, for which the supply is depleted. Similarly, SRMs 2977 and 2978 were developed to replace a previously available (supply depleted) freeze-dried version of SRM 1974a, SRM 2974, Organics in Freeze-Dried Mussel Tissue. SRM 1974b is the third in a series of fresh frozen mussel tissue homogenate SRMs prepared from mussels collected in Boston Harbor starting in 1988. SRM 1974b has certified concentration values for 22 polycyclic aromatic hydrocarbons (PAHs), 31 polychlorinated biphenyl congeners (PCBs), and 7 chlorinated pesticides. Reference values are provided for additional constituents: 16 PAHs, 8 PCBs plus total PCBs, 6 pesticides, total extractable organics, methylmercury, and 11 trace elements. PAH concentrations range from about 2 ng g(-1 )dry mass (cyclopenta[ cd]pyrene) to 180 ng g(-1 )dry mass (pyrene). PCB concentrations range from about 2 ng g(-1 )dry mass (PCB 157) to 120 ng g(-1 )dry mass (PCB 153). The reference value for total PCBs in SRM 1974b is (2020 +/- 420) ng g(-1 )dry mass. Pesticide concentrations range from about 4 ng g(-1 )dry mass (4,4'-DDT) to 40 ng g(-1 )dry mass (4,4'-DDE). SRM 2977 has certified values for 14 PAHs, 25 PCB congeners, 7 pesticides, 6 trace elements, and methylmercury. Reference values for 16 additional PAHs and 9 inorganic constituents are provided, and information values are given for 23 additional trace elements. SRM 2978 has certified and reference concentrations for 41 and 22 organic compounds, respectively, and contains contaminant levels similar to those of SRM 1974b. Organic contaminant levels in SRM 2977 (mussels from Guanabara Bay, Brazil) are typically a factor of 2 to 4 lower than those in SRM 1974b and SRM 2978. The organic contaminant concentrations in each new mussel tissue SRM are presented and compared in this paper. In addition, a chronological review of contaminant concentrations associated with mussels collected in Boston Harbor is discussed as well as a stability assessment of SRM 1974a.

Animals↗
PubMed2007

Event-specific quantitative detection of nine genetically modified maizes using one novel standard reference molecule.

With the development of genetically modified organism (GMO) detection techniques, the Polymerase Chain Reaction (PCR) technique has been the mainstay for GMO detection, and real-time PCR is the most effective and important method for GMO quantification. An event-specific detection strategy based on the unique and specific integration junction sequences between the host plant genome DNA and the integrated gene is being developed for its high specificity. This study establishes the event-specific detection methods for TC1507 and CBH351 maizes. In addition, the event-specific TaqMan real-time PCR detection methods for another seven GM maize events (Bt11, Bt176, GA21, MON810, MON863, NK603, and T25) were systematically optimized and developed. In these PCR assays, the fluorescent quencher, TAMRA, was dyed on the T-base of the probe at the internal position to improve the intensity of the fluorescent signal. To overcome the difficulties in obtaining the certified reference materials of these GM maizes, one novel standard reference molecule containing all nine specific integration junction sequences of these GM maizes and the maize endogenous reference gene, zSSIIb, was constructed and used for quantitative analysis. The limits of detection of these methods were 20 copies for these different GM maizes, the limits of quantitation were about 20 copies, and the dynamic ranges for quantification were from 0.05 to 100% in 100 ng of DNA template. Furthermore, nine groups of the mixed maize samples of these nine GM maize events were quantitatively analyzed to evaluate the accuracy and precision. The accuracy expressed as bias varied from 0.67 to 28.00% for the nine tested groups of GM maize samples, and the precision expressed as relative standard deviations was from 0.83 to 26.20%. All of these indicated that the established event-specific real-time PCR detection systems and the reference molecule in this study are suitable for the identification and quantification of these GM maizes.

Base Sequence↗
PubMed2006

Advances in Huntington's disease diagnostics: development of a standard reference material.

Huntington's disease (HD) is a neurodegenerative disease that affects four to seven individuals per 100,000. The onset of symptoms usually begins in middle age, although approximately 5% become symptomatic as juveniles. Death occurs approximately 15 years following the onset of symptoms, which include choreic movements, cognitive decline and psychiatric changes. HD is an autosomal dominant inherited disease that is associated with an expansion of a trinucleotide (CAG) repeat located on chromosome 4. Physicians rely on a positive family history, and diagnostic and genetic tests to detect the expansion in the number of CAG trinucleotide repeats in the HD gene to confirm the diagnosis. More than 99% of HD patients have 40 or more CAG triplet repeats and, therefore, targeted mutational analysis is greater than 99% sensitive. Individuals with 26 triplet repeats or less are normal, and while those with 27-35 repeats may not demonstrate symptoms themselves, their offspring may have the disease. Individuals with 36-39 repeats may or may not exhibit symptoms. The College of American Pathology/American College of Medical Genetics Biochemical and Molecular Genetics Resource Committee has emphasized the need to standardize the methodology for the determination of the accurate number of CAG repeats. This will prevent false-positive or -negative results when conducting predictive or prenatal testing of at-risk individuals. The National Institute of Standards and Technology is developing a standard reference material to provide these positive and negative controls needed by clinical testing laboratories. The use of a HD standard reference material will provide the quality control and assurance that data from different laboratories are both comparable and accurate.

Alleles↗
PubMed1992

[Tocopherol acetate reference standard (Control 911) of the National Institute of Hygienic Sciences].

The raw material for tocopherol acetate was tested for preparation of the "Tocopherol Acetate Reference Standard (Control 911)". Analytical data obtained were as follows: infrared spectrum, same as Tocopherol Acetate Reference Standard (Control 881); absorptivity, E1cm1% (284nm) = 43.5; thin-layer chromatography, no impurities were detected up to 50.0 micrograms; high performance liquid chromatography (HPLC), two impurities were detected; assay, 100.3% by HPLC. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Standard (Control 911).

Chromatography, High Pressure Liquid↗