PubMed · 4155075
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M Heidelberger. Problems in immunology.. https://pubmed.ncbi.nlm.nih.gov/4155075/
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F2-Isoprostanes are stable lipid peroxidation products of arachidonic acid, the quantification of which provides an index of oxidative stress in vivo. We describe a method for analysing isoprostaglandin F2alpha type III (15-F2t-IsoP) in biological fluids. The method involves solid-phase extraction on octadecyl endcapped and aminopropyl cartridges. After conversion to trimethylsilyl ester trimethylsilyl ether derivatives, isoprostaglandin F2alpha type III is analysed by mass spectrometry, operated in electronic impact selected ion monitoring mode. We have compared enzyme immunoassay (EIA; Cayman, Ann Arbor, MI, USA) to this method with 30 human urine aliquots following the same extraction procedure in order to determine the agreement between both methods. Isoprostaglandin F2alpha type III concentrations determined with gas chromatography-mass spectrometry (GC-MS) did not agree with those determined with EIA. Our results suggest that GC-MS and EIA do not measure the same compounds. As a consequence, comparison of clinical results using GC-MS and EIA should be avoided.
Homology between the 120 envelope glycoprotein of HIV-1 virus and alpha-lactalbumin (a milk protein) stimulated interest in analysis of antibody in HIV-1 positive plasma to cow's milk. Western blots of a two-dimensional (2-D) separation of milk were assayed with nine HIV-1 positive plasmas and nine control sera. The control sera from reference labs represented various disease problems. All nine HIV-1 positive plasma had antibody to between two and five milk proteins. All nine HIV-1 positive plasma had antibody to albumin and immunoglobulin (IgG); in addition, seven reacted with butyrophilin, five with alpha-lactalbumin, six with casein. Four of the control sera had no antibody to milk proteins; three had minor reactivity to casein and two, one diagnosed as an IgM Lyme positive, one diagnosed with Helicobacter pylori detected three and four milk proteins. None of the control sera had antibody to albumin or alpha-lactalbumin. Bovine and human albumin have almost identical sequence, and antibody generated to bovine serum albumin could react with human serum albumin. To look at this, three of the HIV-1 positive plasmas were assayed with 2-D Western blots of human milk and did have reactivity with albumin and IgG. Also, the protein butyrophilin is highly immunogenic and has significant homology with human neural and cellular proteins. Whether these antibodies can be causing allergy or autoimmune disease is speculative, but they indicate an immune system which is highly activated.
We evaluated a new point-of-care (POC) device for urine drugs of abuse (DOA) screening including appropriate clinical interpretation and potential benefits in a large academic medical center. Two hundred consecutive urine samples were tested using Syva Rapid Test (SRT) and existing laboratory methods (Syva EMIT II). Agreement between methods was acceptable with some considerations. Threshold concentration differences, drug interferences, and cross-reactivity profiles of the class-specific assays resulted in performance differences between the POC and central laboratory methods. Clinical interpretation of POC results requires an understanding of these issues as well as the limitations of urine testing. While urine-based screening is used in workplace testing and in a variety of clinical applications, quantitative blood measurements of some drugs (e.g. ethanol, acetaminophen, salicylate, +/-tricyclic antidepressants) will remain important in the emergent setting. Performance of the SRT method takes approximately 10 min. Consequently, the major advantage over laboratory methods is rapid turnaround time. At the Massachusetts General Hospital, the most important application is for samples from the emergency department (about 1700/year). Each institution should assess its own needs and capabilities with regard to POC versus laboratory-based testing for DOA.