[Medical decision in a very elderly patient: a case report of application of the Leonetti law in emergency medicine]. / Décision médicale chez la personne très âgée: à propos d'un cas d'application de la loi Leonetti en médecine d'urgence.

Advanced care decision in emergency medicine is difficult for the elderly. How to be fair, avoiding an unreasonable obstinacy? Based on the case of very old person, we show how an optimal management can be decided in accordance with the spirit of the law.

Stability of pressure-extruded liposomes made from archaeobacterial ether lipids.

Ether lipids were obtained from a wide range of archaeobacteria grown at extremes of pH, temperature, and salt concentration. With the exception of Sulfolobus acidocaldarius, unilamellar and/or multilamellar liposomes could be prepared from emulsions of total polar lipid extracts by pressure extrusion through filters of various pore sizes. Dynamic light scattering, and electron microscopy revealed homogeneous liposome populations with sizes varying from 40 to 230 nm, depending on both the lipid source and the pore size of the filters. Leakage rates of entrapped fluorescent or radioactive compounds established that those archaeobacterial liposomes that contained tetraether lipids were the most stable to high temperatures, alkaline pH, and serum proteins. Most ether liposomes were stable to phospholipase A2, phospholipase B and pancreatic lipase. These properties of archaeobacterial liposomes make them attractive for applications in biotechnology.

Use of natural mRNAs in the cell-free protein-synthesizing systems of the moderate halophile Vibrio costicola.

In vitro protein synthesis was studied in extracts of the moderate halophile Vibrio costicola by using as mRNAs the endogenous mRNA of V. costicola and the RNA of the R17 bacteriophage of Escherichia coli. Protein synthesis (amino acid incorporation) was dependent on the messenger, ribosomes, soluble cytoplasmic factors, energy source, and tRNA(FMet) (in the R17 RNA system) and was inhibited by certain antibiotics. These properties indicated de novo protein synthesis. In the V. costicola system directed by R17 RNA, a protein of the same electrophoretic mobility as the major coat protein of the R17 phage was synthesized. Antibiotic action and the response to added tRNA(FMet) showed that protein synthesis in the R17 RNA system, but not in the endogenous messenger system, absolutely depended on initiation. Optimal activity of both systems was observed in 250 to 300 mM NH4+ (as glutamate). Higher salt concentrations, especially those with Cl- as anion, were generally inhibitory. The R17 RNA-directed system was more sensitive to Cl- ions than the endogenous system was. Glycine betaine stimulated both systems and partly overcame the toxic effects of Cl- ions. Both systems required Mg2+, but in lower concentrations than the polyuridylic acid-directed system previously studied. Initiation factors were removed from ribosomes by washing with 3.0 to 3.5 M NH4Cl, concentrations about three times as high as that needed to remove initiation factors from E. coli ribosomes. Washing with 4.0 M NH4Cl damaged V. costicola ribosomes, although the initiation factors still functioned. Cl- ions inhibited the attachment of initiation factors to tRNA(FMet) but had little effect on binding of initiation factors to R17 RNA.

In vitro protein synthesis by the moderate halophile Vibrio costicola: site of action of Cl- ions.

In vitro protein synthesis in Vibrio costicola [poly(U)-directed incorporation of phenylalanine] was studied. The extent of protein synthesis was limited by the number of ribosomes present. Density gradient centrifugation experiments suggested that, after runoff of ribosomes from the artificial messenger, the 50S subunit was unable to attach to the 30S-messenger complex. As shown previously (M. Kamekura and D. J. Kushner, J. Bacteriol. 160:385-390, 1984), Cl- ions inhibited protein synthesis; indeed, the highest rate of synthesis took place in the lowest attainable Cl- concentration (37 mM). The inhibitory effects were partly reversed by glutamate and betaine, both of which are concentrated within cells of V. costicola. The strongest reversal was seen when both glutamate and betaine were present. Cl- ions can prevent binding of ribosomes to poly(U) and displace ribosomes already bound to this artificial messenger. The effects of Cl- ions on binding were also reversed by glutamate and betaine. Cl- ions did not affect accuracy of translation; they were shown previously (Kamekura and Kushner, J. Bacteriol. 160:385-390, 1984) not to affect phenylalanyl-tRNA synthetase. It was also found that washing ribosomes with inhibitory NaCl concentrations did not interfere with their ability to carry out protein synthesis later in optimal (low) salt concentrations. On the contrary, these ribosomes were more active than before they were washed. We conclude that the main site of action of Cl- in the system studied is on the binding of ribosomes to the mRNA.

In vitro depletion of clonogenic cells in adult acute lymphoblastic leukemia with a CD10 (anti-cALLA) monoclonal antibody.

A semi-solid medium colony assay was used in common acute lymphoblastic leukemia (cALL) to test growth inhibition of leukemic progenitors (CFU-L) after exposure to monoclonal antibodies (MoAbs) directed against CD10 and CD9 antigens. Peripheral or bone marrow cells from 15 patients were plated after exposure to various concentrations of ALB2, a CD10 cytotoxic MoAb, followed by complement lysis. CFU-L inhibition was complete (no residual colony) in 5 cases (33%), marked (greater than or equal to 95%) in 4 cases (27%), but only moderate (64% +/- 28) in 6 cases (40%). This inhibition was not related to the percentage of cALLA positive cells before exposure to MoAb. In addition, cells of 5 patients were exposed to BA1 (CD24) + complement. In these cases, the proportion of CFU-L inhibition was equal to or higher than with ALB2. In 3 cases, cells were exposed to an association of ALB2 and SB4 (CD19) MoAbs followed by complement lysis, with a marked inhibition (greater than or equal to 99%) in 2/3 cases. These observations give supplementary support to the use of several MoAbs directed against various antigens present at early stages of B differentiation.

Merocyanine 540 staining of human leukemic cells: relation to stage of disease.

Previous work based on fluorescence microscopic observation has indicated that leukemic leukocytes and immature hematopoietic precursor cells show a greater permeability to the membrane stain, merocyanine 540 (MC) than normal, mature cells and that changes in MC permeability seem to be correlated with failure in membrane maturation during leukemic cell differentiation. In the interest of addressing questions concerning the efficacy of the MC staining reaction as a diagnostic tool in clinical contexts relevant to leukemia, we have looked for any correlations which might exist between the MC staining patterns displayed by circulating leukocytes, cellular morphology and the clinical status of 53 patients with leukemia and non-Hodgkin's lymphoma, using fluorescence activated cell sorting. In 85% of cases, MC staining was found to be correlated with blood status while in 15% of the cases discrepancies were found. These results are discussed in light of changes in the hematologic profiles of the patients during the clinical course.

Decrease in human lymphocyte surface glycoconjugates in leukemia as demonstrated by lectin binding.

Qualitative variations in the glycoconjugates which make up the lectin receptor sites on the membranes of leukemic lymphocytes, compared with those of normal cells, have been studied by the use of three tritiated lectins: Robinia pseudoacacia lectin, Concanavalin A and Ricinus communis (var. Sanquineus) agglutinin (RCA 120). The binding specificity of these lectins has been demonstrated using specific determinants: alpha-methylmannoside and galactose for Concanavalin A and Ricinus communis agglutinin respectively. For the Robinia lectin this specificity was determined by saturation of the receptor sites with the unlabeled Robinia lectin before the addition of isotopically labeled Robinia lectin. The results show a decrease in the number of receptor sites on the leukemia cells, especially in chronic lymphoid leukemia, relative to that on normal cells. The apparent affinity constants of leukemic cells in all cases remain higher than those of normal cells.

Application of colored image analysis to bone marrow cell recognition.

A color processing procedure bases on the essential features of human perception of colors is presented. It allows the computation of colors in terms of the luminance, the hue and the saturation at every point of an image. Such color processing was used for segmentation and feature extraction of human bone marrow cell images acquired through successive red, green and blue broad-band filters. The efficiency of the luminance, saturation and hue parameters in discriminating cell types is illustrated and discussed.

Modifications of lectin binding on human leukemic cells after neuraminidase treatment.

Cell surface modifications after vibrio cholerae neuraminidase treatment were investigated using three different tritiated lectins: Concanavalin A, Ricinus sanguineus agglutinin (R.S.A.) and Robinia pseudoacacia lectin. Lectin binding measurements were performed on untreated and enzyme treated cells. The cells used were from chronic and acute leukemic donors. After neuraminidase treatment, a significant increase in the number of receptor sites, from 1 to 3 times, was found in all cases tested and for all three lectins utilized with only one exception. The affinity constant was generally decreased after neuraminidase treatment. The increase in number lectin binding sites, indicating extensive modification of the cell surface, is completely consistant with the known importance of sialic acid in determining immunogenicity.

Quantitative variations of three different lectin receptors as a function of establishment and metabolism of normal and leukaemic human cell lines.

Lectin binding on the cell surface was measured by the method of Kornfeld [16] using three tritiated lectins: Robinia pseudo acacia, Concanavalin A and Ricinus. It has been shown that the number of binding sites for Robinia and Con A decreases after the establishment of a leukaemic cell line, whereas the affinity constant increases for Robinia. The relationship between lectin binding and cell growth was carried out on 5 cell lines, 3 of leukaemic and 2 of normal origin. In all cases the maximum number of sites was determined at the time of doubling for the cell population; the affinity constant reciprocally decreases at this moment. For Robinia, a difference was found in both cell growth and the number of sites between an Epstein-Barr virus (EBV) negative leukaemic cell line and the other EBV positive cell lines. Lectins offer a quantitative method for measuring membrane structure variations during and after establishment of cell lines.