Method-dependent variations in the stability of apolipoprotein B in a stabilized liquid reference material

1994 ◽  
Vol 40 (5) ◽  
pp. 716-722 ◽  
Author(s):  
J V Mei ◽  
M K Powell ◽  
L O Henderson ◽  
S J Smith ◽  
G R Cooper ◽  
...  
Keyword(s):  
Reference Material ◽  
Apolipoprotein B ◽  
Clinical Chemistry ◽  
Immunological Methods ◽  
Apo B ◽  
Human Apolipoprotein ◽  
The Stability ◽  
Measured Mass ◽  
Thermal Stability Of

Abstract Using accelerated Arrhenius-type short-term and long-term temporal studies, we evaluated the storage life of a stabilized, liquid-frozen reference material (SLRM) for human apolipoprotein B (apo B) developed by the International Federation of Clinical Chemistry. As measured by our candidate reference RIA, the concentrations of immunoreactive apo B in the SLRM showed pronounced degradation with exposure to increasing temperatures over time. The SLRM was stable for as long as 1 year when stored at - 70 degrees C, but its immunoreactive apo B declined by < 10% when stored at 4 degrees C for 10 months. Using radial immunodiffusion and an ELISA to assess the equivalency of measured mass for the accelerated thermal stability of the SLRM, we found a loss of immunoreactive apo B similar to that measured by RIA. Analyzing the same samples by liquid immunoprecipitation (nephelometry) resulted in the amount of apo B present being overestimated, especially in samples held for long periods. By using different immunological methods to evaluate this thermally aged SLRM, we demonstrated that its measured behavior varies depending on the method of quantitation.

International Federation of Clinical Chemistry standardization project for measurements of apolipoproteins A-I and B. IV. Comparability of apolipoprotein B values by use of International Reference Material

1994 ◽  
Vol 40 (4) ◽  
pp. 586-592 ◽  
Author(s):  
S M Marcovina ◽  
J J Albers ◽  
H Kennedy ◽  
J V Mei ◽  
L O Henderson ◽  
...  
Keyword(s):  
Reference Material ◽  
Apolipoprotein B ◽  
Matrix Effects ◽  
Clinical Chemistry ◽  
Sodium Dodecyl ◽  
International Federation ◽  
World Health ◽  
Apo B ◽  
B Values ◽  
International Reference

Abstract We performed temporal and thermal stability studies on SP3-07, a liquid-stabilized reference material for apolipoprotein (apo) B, selected during the previous phase of the International Federation of Clinical Chemistry project on standardization of apolipoprotein measurements. Results indicate that SP3-07 stored at -70 degrees C has the long-term stability required for a reference material. We assigned an accuracy-based apo B value of 1.22 g/L to SP3-07, using a nephelometric method that was calibrated with freshly isolated low-density lipoprotein for which the apo B mass value was determined by a standardized sodium dodecyl sulfate-Lowry procedure. Using a common protocol, the study participants transferred the assigned mass value from SP3-07 to the individual calibrators of the analytical systems and measured the apo B concentration of 20 fresh-frozen samples obtained from individual donors and covering a clinically relevant range of apo B values. The among-laboratory CV on these samples, analyzed by 25 analytical systems, ranged from 3.1% to 6.7%. These results demonstrate the lack of matrix effects of SP3-07 and its ability to provide accurate and comparable apo B values in a variety of immunochemical methods. On the basis of the outcome of these studies, the World Health Organization has endorsed SP3-07 as the International Reference Material for Apolipoprotein B.

scholarly journals The mechanism by which the human apolipoprotein B gene reducer operates involves blocking of transcriptional activation by hepatocyte nuclear factor 3.

1993 ◽  
Vol 13 (3) ◽  
pp. 1534-1546 ◽  
Author(s):  
B Paulweber ◽  
F Sandhofer ◽  
B Levy-Wilson
Keyword(s):  
Binding Site ◽  
Transcriptional Activation ◽  
Apolipoprotein B ◽  
Regulatory Protein ◽  
Nuclear Factor ◽  
Hepatocyte Nuclear Factor ◽  
Apo B ◽  
Human Apolipoprotein ◽  
Colon Carcinoma Cells ◽  
Mediator Protein

Previously, we showed that when a DNA fragment extending from -3067 to -2734 of the human apolipoprotein B (apo-B) gene is inserted immediately upstream of an apo-B promoter segment (-139 to +121), transcription from this promoter is reduced by about 10-fold in cultured colon carcinoma cells (CaCo-2) but not in cultured hepatoma cells (HepG2). We postulated that this reducer operates by a mechanism involving active repression of a transcriptional activator that binds to the segment from -111 to -88 of the apo-B promoter (B. Paulweber and B. Levy-Wilson, J. Biol. Chem. 266:24161-24168 1991). In the current study, the reducer element has been localized to a 24-bp sequence from -2801 to -2778 of the apo-B gene that contains a binding site for the negative regulatory protein ARP-1. Furthermore, we have demonstrated that the transcription factor hepatocyte nuclear factor 3 alpha (HNF-3 alpha) binds to the sequence 5'-TGTTTGCTTTTC-3' from -95 to -106 of the apo-B promoter, to stimulate transcription. Transcriptional activation by HNF-3 is repressed when the reducer sequence is inserted immediately upstream of the HNF-3 binding site, suggesting a mechanism by which the reducer-bound protein blocks the activation promoted by HNF-3. Data from cotransfection experiments in which ARP-1 is overexpressed in the absence of its binding site suggest that ARP-1 interacts either directly or via a mediator protein with proteins recognizing the HNF-3 site and that this interaction is sufficient to repress transcriptional activation by HNF-3. Because transcriptional activation by Sp1 is not affected by the reducer, it is unlikely that the reducer interacts directly with basic components of the transcriptional machinery.

scholarly journals DNase I- and micrococcal nuclease-hypersensitive sites in the human apolipoprotein B gene are tissue specific.

1988 ◽  
Vol 8 (1) ◽  
pp. 71-80 ◽  
Author(s):  
B Levy-Wilson ◽  
C Fortier ◽  
B D Blackhart ◽  
B J McCarthy
Keyword(s):  
Hela Cells ◽  
Apolipoprotein B ◽  
Hepg2 Cells ◽  
Transcriptional Start Site ◽  
Dnase I ◽  
Micrococcal Nuclease ◽  
Apo B ◽  
Human Apolipoprotein ◽  
Hypersensitive Sites ◽  
High Degree

We have mapped the DNase I- and micrococcal nuclease-hypersensitive sites present in the 5' end of the human apolipoprotein B (apo-B) gene in nuclei from cells expressing or not expressing the gene. Four DNase I-hypersensitive sites were found in nuclei from liver-derived HepG2 cells and intestine-derived CaCo-2 cells, which express the apo-B gene, but not in HeLa cells, which do not. These sites are located near positions -120, -440, -700, and +760 base pairs relative to the transcriptional start site. Undifferentiated CaCo-2 cells exhibited another site, near position -540. Six micrococcal nuclease-hypersensitive sites were found in nuclei from HepG2 and CaCo-2 cells, but not in HeLa cells or free DNA. These sites are located near positions -120, -390, -530, -700, -850, and +210. HepG2 cells exhibited another site, near position +460. Comparison of the DNA sequence of the 5' flanking regions of the human and mouse apo-B genes revealed a high degree of evolutionary conservation of short stretches of sequences in the immediate vicinity of each of the DNase I- and most of the micrococcal nuclease-hypersensitive sites.

The Thermal Stability of a Single-Grain Mg-Zn-Y Icosahedral Quasicrystal

2000 ◽  
Vol 643 ◽  
Author(s):  
Z.P. Luo ◽  
Y.L. Tang ◽  
D.J. Miller ◽  
M.J. Kramer ◽  
I.R. Fisher ◽  
...  
Keyword(s):  
Golden Ratio ◽  
Lattice Parameter ◽  
Icosahedral Quasicrystal ◽  
Face Centered Cubic ◽  
Single Grain ◽  
Face Centered ◽  
The Stability ◽  
Mg Content ◽  
Thermal Stability Of

AbstractThe stability of the Mg-Zn-Y icosahedral quasicrystal (IQC) has been studied by long-term annealing of a single grain IQC in quartz tubes. Decomposition of the IQC was observed after annealing at high temperatures (T≥773 K) sealed in Ar. During the decomposition process, the quasilattice parameter aR was found to decrease, associated with a decrease in Mg content of the IQC phase as confirmed by quantitative x-ray energy dispersive spectroscopy analyses. In addition, a new cubic approximant has been found in the annealed samples. This cubic approximant has a face-centered cubic (fcc) structure with lattice parameter of a = 1.276 nm, which is about (1/τ) times smaller than that of the fcc W'-(MgZnY) with a = 2.05 nm reported previously (where τ is the golden ratio).

SANS study on the stability of oxide nanoparticles in long-term thermally aged 9Cr-ODS steel

2021 ◽  
Author(s):  
Peng-Lin Gao ◽  
Jian Gong ◽  
Qiang Tian ◽  
Gung-Ai Sun ◽  
Hai-Yang Yan ◽  
...  
Keyword(s):  
Oxide Dispersion Strengthened ◽  
Oxide Nanoparticles ◽  
Electron Backscattered Diffraction ◽  
Excellent Thermal Stability ◽  
Ods Steel ◽  
Transmission Electron ◽  
Hardness Tests ◽  
The Stability ◽  
Thermal Stability Of

Abstract A 9Cr-oxide dispersion strengthened (ODS) steel was thermally aged at 873 K for up to 5000 hours. The size distribution and chemical composition of the dispersed oxide nanoparticles were analyzed by small angle neutron scattering (SANS) method under magnetic field. Combined with transmission electron microscopy (TEM), Vickers micro-hardness tests and electron backscattered diffraction (EBSD) measurements, all the results showed that the thermal treatment had little or no effect on the size distributions and volume fractions of the oxide nanoparticles in the ferromagnetic matrix, which suggested excellent thermal stability of the 9Cr-ODS steel.

The mechanism by which the human apolipoprotein B gene reducer operates involves blocking of transcriptional activation by hepatocyte nuclear factor 3

1993 ◽  
Vol 13 (3) ◽  
pp. 1534-1546
Author(s):  
B Paulweber ◽  
F Sandhofer ◽  
B Levy-Wilson
Keyword(s):  
Binding Site ◽  
Transcriptional Activation ◽  
Apolipoprotein B ◽  
Regulatory Protein ◽  
Nuclear Factor ◽  
Hepatocyte Nuclear Factor ◽  
Apo B ◽  
Human Apolipoprotein ◽  
Colon Carcinoma Cells ◽  
Mediator Protein

Previously, we showed that when a DNA fragment extending from -3067 to -2734 of the human apolipoprotein B (apo-B) gene is inserted immediately upstream of an apo-B promoter segment (-139 to +121), transcription from this promoter is reduced by about 10-fold in cultured colon carcinoma cells (CaCo-2) but not in cultured hepatoma cells (HepG2). We postulated that this reducer operates by a mechanism involving active repression of a transcriptional activator that binds to the segment from -111 to -88 of the apo-B promoter (B. Paulweber and B. Levy-Wilson, J. Biol. Chem. 266:24161-24168 1991). In the current study, the reducer element has been localized to a 24-bp sequence from -2801 to -2778 of the apo-B gene that contains a binding site for the negative regulatory protein ARP-1. Furthermore, we have demonstrated that the transcription factor hepatocyte nuclear factor 3 alpha (HNF-3 alpha) binds to the sequence 5'-TGTTTGCTTTTC-3' from -95 to -106 of the apo-B promoter, to stimulate transcription. Transcriptional activation by HNF-3 is repressed when the reducer sequence is inserted immediately upstream of the HNF-3 binding site, suggesting a mechanism by which the reducer-bound protein blocks the activation promoted by HNF-3. Data from cotransfection experiments in which ARP-1 is overexpressed in the absence of its binding site suggest that ARP-1 interacts either directly or via a mediator protein with proteins recognizing the HNF-3 site and that this interaction is sufficient to repress transcriptional activation by HNF-3. Because transcriptional activation by Sp1 is not affected by the reducer, it is unlikely that the reducer interacts directly with basic components of the transcriptional machinery.

A Highly Sensitive Assay for Quantitation of Apolipoprotein B48 Using an Antibody to Human Apolipoprotein B and Enhanced Chemiluminescence

1997 ◽  
Vol 34 (2) ◽  
pp. 185-189 ◽  
Author(s):  
Darrin Smith ◽  
Spencer D Proctor ◽  
John C L Mamo
Keyword(s):  
Apolipoprotein B ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Apo B ◽  
Human Apolipoprotein ◽  
Enhanced Chemiluminescence ◽  
Coomassie Blue ◽  
Sds Page ◽  
One Step ◽  
Apolipoprotein B48

We describe a method for the rapid quantification of serum apolipoprotein B48 using a commercially available anti-apolipoprotein (apo)B antiserum and compare it to analytical sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) with coomassie blue R250 staining. The method described here eliminates the need for de-lipidation of samples and only requires a one-step overnight ultracentrifugation. Western-blotting and enhanced chemiluminescence (ECL) visualization of proteins was approximately 10 times more sensitive than coomassie staining and generally took no longer to complete than staining/destaining of SDS-PAGE gels. The sensitivity of the antiserum/ECL technique enabled quantitation of fasting apolipoprotein B48 which could not be resolved by SDS-PAGE and Coomassie staining.

Thermal Stability of Ti-6Al-4V Alloy with Carbon Content

2015 ◽  
Vol 226 ◽  
pp. 23-28
Author(s):  
Agnieszka Szkliniarz
Keyword(s):  
Carbon Content ◽  
Operating Temperature ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Hardness Test ◽  
Two Phase ◽  
Microstructure Stability ◽  
The Stability ◽  
Thermal Stability Of

In the paper, the effect of long-term annealing (to 500 h) on the microstructure and hardness of two-phase titanium alloy which represent group of α+β (Ti-6Al-4V) with 0.7 wt. % carbon content was present. The stability of microstructure after long-term annealing was conducted to alloys in hardening state (after solution treatment and aging). Annealing was carried out at a temperature above the operating temperature of commercial titanium alloys without carbon content. The analysis of changes in the microstructure at research range of annealing time indicates its stability, which was confirmed by hardness test of investigated alloys. For comparison to Ti-6Al-4V-0.7C alloy, the microstructure stability research at 420oC was conducted for classical alloy contain no carbon. This alloy was previously subject solution and aging treatment under the same conditions as tested alloy.

International Federation of Clinical Chemistry standardization project for measurements of apolipoproteins A-I and B

1991 ◽  
Vol 37 (10) ◽  
pp. 1676-1682 ◽  
Author(s):  
S M Marcovina ◽  
J J Albers ◽  
F Dati ◽  
T B Ledue ◽  
R F Ritchie
Keyword(s):  
Reference Material ◽  
Reference Materials ◽  
Clinical Chemistry ◽  
Collaborative Study ◽  
International Federation ◽  
Apo B ◽  
Suitable Candidate ◽  
Candidate Reference Material ◽  
Test Systems ◽  
Suitable Reference

Abstract To minimize differences in apolipoprotein measurements among laboratories and methods, a standardization program involving common suitable reference material is needed. The Committee on Apolipoproteins of the International Federation of Clinical Chemistry initiated a collaborative study for the standardization of test systems for measuring apolipoproteins (apo) A-I and B, with 25 company laboratories and three research laboratories involved in apolipoprotein analysis to: (a) evaluate calibration differences among the test systems; (b) evaluate whether comparability of the data can be achieved with the use of frozen serum pools to recalibrate the different systems; and (c) evaluate and select suitable candidate reference material. We used 26 test systems for apo A-I and 28 for apo B. Relatively modest differences were found in calibration for apo A-I, but very wide differences were observed for apo B methods. After uniform calibration, the overall among-laboratory CV for apo B decreased from 19% to 6%. Three lyophilized serum preparations for apo A-I and three liquid-stabilized serum preparations for apo B were selected for further evaluation as candidate international reference materials.

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