Neonatal screening for hyperlipoproteinemia. Methods for direct estimation of cord serum VLDL + LDL.

The early detection of hyperlipoproteinemia in newborn infants has so far been based upon estimation of cord blood total lipids (cholesterol and triglyceride) and lipoprotein-lipids (VLDL-, LDL- and HDL-cholesterol). To be able to make a direct estimation of cord serum beta-lipoproteins (VLDL + LDL) two quite different methods were modified, one immunological and the other turbidimetric. Good correlations were found to VLDL- + LDL-cholesterol isolated in the ultracentrifuge (r = 0.848 and 0.831, respectively). If neonatal screening for hyperlipoproteinemia is considered, we recommend the very easy and inexpensive turbidimetric method. Furthermore, using cord serum, two conventional precipitation methods with heparin-CaCl2 and heparin-MnCl2 were compared by ultracentrifugation and high correlations were found (r = 0.923 and 0.899, respectively). A clamping study showed that following early clamping of the cord, the concentration of cord serum lipids and lipoproteins did not change markedly within the first five minutes. Storing experiments showed that serum should be separated within the first 12 h to avoid unpredictable changes in the concentration of cord serum lipids and lipoproteins.     

Body composition measurement by dual photon absorptiometry: comparison with body density and total body potassium measurements

Summary. Body composition was measured in 29 healthy adults (12 men and 17 women) by three different methods: Dual photon (¹⁵³Gd) absorptiometry (DPA), body density measurements (BD) and measurements of total body potassium (TBK). Correlation and regression analysis with the body fat percentage (Fat%) measured by the three different methods gave r values between 0·83 and 0·90 and SEEs between 4·0 and 6·0 (Fat%). We conclude that DPA provides a new method of measuring body composition with precision and accuracy errors in the same range as the more established methods.     

Frequency of MART-1/MelanA and gp100/PMel17-specific T cells in tumor metastases and cultured tumor-infiltrating lymphocytes

Melanoma differentiation antigens, such as MART-1/MelanA and gp100/PMel17, frequently are observed as targets of tumor infiltrating lymphocytes (TIL) originated from HLA-A*0201-expressing patients with melanoma. Furthermore, particular clinical relevance was attributed to gp100/pMel17 based on the impression that the adoptive transfer of gp100-recognizing TIL was associated with clinical responses in a small group of patients. However, the actual frequency of specific T cells for these melanoma differentiation antigens has never been directly enumerated in ex vivo or in vitro expanded TIL cultures. Here, we enumerated melanoma differentiation antigen-specific T-cell precursor frequency in TIL using tetrameric HLA/epitope complexes, functionally characterizing their responsiveness to cognate epitope by cytokine release assay. T-cell precursor frequencies were enumerated in 11 fresh-tumor preparations and 17 TIL adoptively transferred into patients bearing HLA-A*0201. MART-1 or gp100-specific T cells could be detected respectively in 5 and 2 of the 11 fresh preparations and in 5 and 2 of the 17 adoptively transferred TIL. With one exception, melanoma differentiation antigen-specific T-cell precursor frequency in fresh material and TIL ranged between 5,000 to 21,000/10(6) CD8+ T cells. T-cell precursor frequency was not significantly higher in TIL whose administration was associated with clinical response. These data provide direct enumeration of MART-1/MelanA and gp100/pMel17 reactivity ex vivo and in vitro in the context of HLA-A*0201.     

Solid-phase double-antibody radio-immunoassay for atrial natriuretic factor

A solid-phase radio-immunoassay for the determination of atrial natriuretic factor (ANF) in human plasma is described. Iodination of alpha hANF was carried out with the iodogen method. Purification of radio-iodinated alpha hANF was performed by chromatography on disposable columns of DEAE-Sephadex A-25. Studies of immunoreactivity and the elution pattern on HPLC showed perfect stability of the labelled compounds. The tracer was usable for 28 weeks after preparation, and the batch-to-batch variation in the quality of the tracer was satisfactory. Immunoreactive ANF was extracted from human plasma with Sep-Pak C18 cartridges. Recovery of alpha hANF added to whole blood was 85 +/- 12% (mean +/- SD, n = 12). The sensitivity of the radio-immunoassay was 1.6 pg/tube, equivalent to 1 pg/ml plasma when assaying the extract from 4 ml plasma. Mean plasma ANF values in normal subjects in the supine position was 23 +/- 12 pg/ml (mean +/- SD, n = 21).     

Ig RNA expression in normal B cells stimulated with anti-IgM antibody and T cell-derived growth and differentiation factors

An increase in mRNA encoding the secretory form of the mu heavy (H) chain (mus) and in the ratio of mus mRNA to the mRNA encoding the membrane form of the microH chain (micron) occurs in normal B cells stimulated with anti-IgM and BSF-p1 together with the two B cell differentiation factors B15-TRF and EL-TRF. Stimulation of cells with anti-IgM and BSF-p1 with either B15- or EL-TRF causes no change in mus levels or mus/micron ratios. The requirements for induction of high rate IgM synthesis in normal B cells stimulated with anti-IgM were precisely the same as those required for elevation of mus, mRNA levels and for increase in mus/micron mRNA ratios. A very close correlation also exists between induction of mRNA for J chain and increase in mus mRNA levels. Similarly, the increase in J chain protein concentration and percent of cells with cytoplasmic IgM were correlated to each other and to levels of mus and J chain mRNA. These results indicate that elevation of mus mRNA and mus/micron mRNA ratios occur in normal B cells only upon commitment to IgM synthesis, and reaffirm the close relation between IgM synthesis and the presence of J chain.     

Evaluation and comparison of commercially available pregnancy tests based on monoclonal antibodies to human choriogonadotropin

We evaluated eight pregnancy tests: Tandem Icon, beta-hCG Rapid, Pregnastick (immunoenzymometric assays), Neo-Pregnosticon (direct hemagglutination), Pregnospia (sol particle immunoassay), Neo-Planotest (latex agglutination), Gravindex beta-hCG, and beta-hCG Slide Test (both latex-agglutination inhibition), all of which detect human choriogonadotropin (hCG) in urine. We investigated the limits of detection and the responses to the following substances: human lutropin, protein, and blood, and high concentrations of hCG. Using 100 patients' samples, we assessed the diagnostic specificity and sensitivity as well as the accuracy of each kit. The detection limits for Tandem Icon, beta-hCG Rapid, Neo-Pregnosticon, Pregnospia, Neo-Planotest, and Gravindex beta-hCG were as stated by the manufacturers. Only Neo-Planotest gave a false-positive result for lutropin. The three immunoenzymometric assays were not affected by protein or blood, but of these only Tandem Icon did not exhibit prozoning. The five other kits gave false-positive or false-negative results for protein and blood. Tandem Icon performed best, being quick and easy to use and without susceptibility to interfering substances.     

Extracellular and intracellular killing in neutrophil granulocytes of Staphylococcus aureus with rifampicin in combination with dicloxacillin or fusidic acid

The effect of rifampicin in combination with dicloxacillin or fusidic acid on the extracellular and intracellular killing of Staphylococcus aureus in human neutrophil granulocytes in the presence of serum was studied. At the extracellular level rifampicin significantly reduced the bactericidal activity of dicloxacillin, but had an indifferent effect on the activity of fusidic acid. The combination of rifampicin with dicloxacillin or fusidic acid led to intracellular killing no different from that produced by rifampicin alone. However, owing to the high intracellular activity of rifampicin, the intracellular killing by the drug combinations was greater than that by dicloxacillin or fusidic acid alone.