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At least 19 recordsLinked to original sources
PubMed1990

[National Institute of Hygienic Sciences Standard (the Japanese Pharmacopoeia Standard) "Endotoxin Reference Standard" (Control 891)].

The second "Endotoxin Reference Standard" (Control 891) of the National Hygienic Sciences (Japanese Pharmacopoeia Standard) was prepared. As a result of the test of its potency against the preceding lot of the Reference Standard (Control 881), the second "Endotoxin Reference Standard" (Control 891) containing 16000 endotoxin units per vial was authorized.

Endotoxins↗
PubMed1991

The heterogeneity of human chorionic gonadotropin (hCG). II. Characteristics and origins of nicks in hCG reference standards.

hCG, the hormone produced by the trophoblast throughout pregnancy, has peptide bond cleavages, or nicks, in the beta-subunit. We sought to compare the nature of these nicks in standard reference preparations of hCG, to determine the enzymes that may be responsible for generating the peptide bond cleavages, and to devise means of separating nicked from intact hormone. The standard reference preparations of hCG, which are purified from a commercial product made from large pools of pregnancy urine, were found to have varying concentrations of nicked hormone. The preceding report showed that 11 of 13 hCG preparations isolated from individual pregnancy urine samples were nicked at the beta 47-48 bond, with 2 of 13 having a second nick at beta 44-45. As shown here, all of the hCG reference standards are nicked to similar extents at both the beta 47-48 bond and the beta 44-45 bond. The percentage of peptide bond nicking in the various hCG standard preparations ranged from 10-20% and appeared higher in the more recent preparations. We showed that human leukocyte elastase is capable of specifically cleaving the beta 44-45 bond, and in extended digests it can also cleave the beta 48-49 and beta 51-52 peptide bonds. Thus, human leukocyte elastase may be the origin of some of these cleavages in the individual samples and the reference standards. Furthermore, we report that a monoclonal antibody directed to hCG alpha-beta dimer binds preferentially to nonnicked hCG and much less to nicked hCG.

Amino Acid Sequence↗
PubMed1998

[Retinol Acetate Reference Standard (Control 971) and Retinol Palmitate Reference Standard (Control 971) of National Institute of Health Sciences].

The "Retinol Acetate Reference Standard (Control 971)" and "Retinol Palmitate Reference Standard (Control 971)" of National Institute of Health Sciences using the assay of vitamin A ester were prepared. The proposed materials were evaluated in collaboration with four laboratories. Analytical data obtained were as follows. 1) The purities of retinol acetate and retinol palmitate measured by HPLC were 99.9 +/- 0.06% and 94.5 +/- 0.06%, respectively. 2) ultraviolet spectrum of retinol acetate and retinol palmitate showed the lambda max at 326-327 nm. 3) The difference in relative extinction of retinol acetate and retinol palmitate at 300 nm, 310 nm, 320 nm, 330 nm, 340 nm and 350 nm are within the range provided in JPXIII. 4) The contents of retinol acetate and retinol palmitate were 52,000 IU/g and 52,200 IU/g, respectively. Based on the above results, these proposed materials were authorized to be the Reference Standards of the National Institute of Health Sciences.

Diterpenes↗
PubMed1993

Separation of nicked human chorionic gonadotropin (hCG), intact hCG, and hCG beta fragment from standard reference preparations and raw urine samples.

hCG is found in pregnancy urine and in urine from some cancer patients in a variety of forms whose concentrations have clinical importance. Recently, concerns about accurate measurement of these forms have been raised because of the finding that hCG with peptide bond cleavages within the beta-subunit is not recognized by commonly used antibodies. Such nicked forms of hCG are biologically inactive or of very low activity. They are present in normal pregnancy urine and to varying extents in the urine of patients with trophoblastic disease. International reference preparations of hCG contain nicked forms of hCG. Previously, it was not possible to separate nicked hormone from the intact form of hCG. This was a serious impediment to producing improved reference standards from natural pregnancy hormone. We now report that a simple hydrophobic purification scheme separates intact hCG from nicked hCG as well as from hCG beta core fragment. This scheme is a modification of the method of Hiyama et al. The order of elution from low to high hydrophobicity is hCG beta core fragment, nicked hCG, and lastly, intact hCG. Nicking of the putative amphipathic helix loop, hCG beta 38-57, apparently renders the hormone significantly less hydrophobic despite the equal molar content of sialic acid. The hCG CR 127 nicked preparation was only 10% as potent as the reference preparation in a heterodimer-directed assay. The nicked-depleted hCG CR 127 was 30% more potent in this assay. Improved hCG reference standards should display similar increases in immunopotency (20-30%) with most antiheterodimeric antibodies and similar increases in bio-potency assays. It should now be possible to make reference preparations of these forms of hCG directly from the raw urine of normal pregnant patients and those with trophoblastic disease.

Amino Acid Sequence↗
PubMedDate not supplied

Preparation and examination of proposed consensus reference standards for fiber-counting.

This study provided standard reference materials for fiber-counting by phase-contrast microscopy (PCM). PCM is subject to many sources of variation, including those dependent on the microscopist, so reference standards cannot be produced that are traceable to national or international standard units. Consensus standards using a "true value" agreed on by a number of laboratories may be acceptable. Reference slides for fiber-counting can be prepared using a proprietary process of grid overlay in which the fields of view defined by the grids are identifiable and relocatable. Multiple microscopists then can examine exactly the same areas of samples, reducing one source of potential variation. Twelve slides prepared from proficiency test samples of the American Industrial Hygiene Association (AIHA) Industrial Hygiene Laboratory Quality Program were used in this study, four each of chrysotile asbestos, amosite asbestos, and man-made mineral fibers. Five microscopists from AIHA-accredited laboratories, plus the inventor of the grid process, examined the slides in a blind study. This group represented commercial analytical companies, in-house corporate laboratories, research institutions, and universities. The six microscopists met to obtain consensus agreement on the fibers in each designated field classified as countable under National Institute for Occupational Safety and Health Method 7400. Slides and documentation were forwarded to AIHA for training or other purposes. Examination of the results by statistical methods showed that some microscopists' results were significantly different from others, even though all analysts would have been considered proficient with respect to the final consensus values. Although the reasons for the outliers are complex, this procedure may have value in selecting reference laboratories in proficiency test schemes, possibly leading to more defensible "true" values and tighter limits of variation.

Air Pollution, Indoor↗