Investigation of the calcium-mediated association between the carbohydrate head groups of galactosylceramide and galactosylceramide I3 sulfate by electrospray ionization mass spectrometry

Calcium has been shown previously to cause aggregation of phosphatidylcholine/cholesterol liposomes containing galactosylceramide (GalCer) with similar liposomes containing cerebroside sulfate (galactosylceramide I3 sulfate) (CBS), suggesting that it mediates a carbohydrate-carbohydrate association between these two glycolipids. In order to determine if such an association occurs, the noncovalent complexes formed on addition of calcium chloride to GalCer and CBS in methanol were examined by positive and negative ion spray mass spectrometry. Monomeric Ca2+ complexes of both lipids were observed. In addition, Ca2+ also caused oligomerization of GalCer. Oligomerization of CBS anion was not seen, but dimers would not have been observed, as they would be neutral. However, Ca2+ caused heterotypic complexation of GalCer and CBS. Although these heterotypic complexes were of low abundance in methanol compared with the other monomeric and homotypic oligomeric positive ions formed at low declustering potentials, the heterotypic dimer [GalCer.CBS.Ca2+-H]+ had the greatest stability of all oligomers formed and was the only one to survive at high declustering potentials. Na+ did not cause oligomerization of GalCer in methanol indicating that the complexes of GalCer with Ca2+ are not caused by van der Waals interactions between the lipid moieties. GalCer and CBS are present in high concentrations in myelin. This Ca2+-mediated carbohydrate-carbohydrate interaction, which can bridge apposing bilayers, may be involved in adhesion of the extracellular surfaces of the myelin sheath.     

Ex vivo generation of functional dendritic cells from mobilized CD34+ hematopoietic stem cells

Gene engineering to enhance tumour immunogenicity and elicit curative responses against established tumours and tumour recurrences has become an attractive prospect. Gene engineering enables new genes to be selectively inserted into the genome of a tumour cell, or the construction of new fusion plasmids coding tumour antigens and immunomodulatory molecules. The rationale behind current research is to enhance the immune recognition of tumour antigens through their association with the molecules on which immune recognition depends. The immunotherapy data obtained in many experimental tumour systems provide a realistic assessment of the potential and limits of this technological approach. Experimental vaccination of rodents has been shown to induce a significant immune memory, even against poorly immunogenic tumours, that can prevent tumour growth and cure initial metastases, but is poorly effective against established tumours. Its use in tumour prevention is a fresh dawning perspective.     

Methodology of serial ECG classification using an adaptation of the NOVACODE for Q wave myocardial infarction in the Bypass Angioplasty Revascularization Investigation (BARI)

Serial electrocardiographic (ECG) changes are a critical component of the diagnostic algorithm for classification of myocardial ischemic events in large-scale clinical trials. This study describes a computerized serial ECG classification program developed at the St. Louis University Core ECG Laboratory for use in the Bypass Angioplasty Revascularization Investigation (BARI) trial, in which patients with multivessel coronary artery disease were randomized to receive either coronary artery bypass grafting or percutaneous transluminal coronary angioplasty. The St. Louis University program detects and codes serial changes in Q, ST, and T wave items according to Minnesota code (MC) criteria using a modified NOVACODE hierarchical classification system. Measurements using a seven-power calibrated coding loupe are used to generate the MC from a customized software program. Significant minor or major changes are detected by the serial comparison program and referred to a physician coder for verification. Serial comparison coding rules are used to adjust for weaknesses in the standard MC classification system resulting from instability at decision boundaries. Of 4,244 BARI randomized and registry study participants with follow-up ECGs received at the Core ECG Laboratory as of March 1995, a grade 2 MC Q wave progression was noted in 568 participants (13.4%) using MC criteria alone, as compared with 367 (8.6%) after the St. Louis University coding rules were applied. The incidence of grade 1 MC Q wave progressions was 16.4% (697/4,244) versus 6.1% (259/4,244) when the St. Louis University program was applied. Intraobserver variability for grade 2 Q wave progression codes determined from a sample of 812 serial.     

Recombinant expression and characterization of the major beta-lactamase of Mycobacterium tuberculosis

New antibiotic regimens are needed for the treatment of multidrug-resistant tuberculosis. Mycobacterium tuberculosis has a thick peptidoglycan layer, and the penicillin-binding proteins involved in its biosynthesis are inhibited by clinically relevant concentrations of beta-lactam antibiotics. beta-Lactamase production appears to be the major mechanism by which M. tuberculosis expresses beta-lactam resistance. beta-Lactamases from the broth supernatant of 3- to 4-week-old cultures of M. tuberculosis H37Ra were partially purified by sequential gel filtration chromatography and chromatofocusing. Three peaks of beta-lactamase activity with pI values of 5.1, 4.9, and 4.5, respectively, and which accounted for 10, 78, and 12% of the total postchromatofocusing beta-lactamase activity, respectively, were identified. The beta-lactamases with pI values of 5.1 and 4.9 were kinetically indistinguishable and exhibited predominant penicillinase activity. In contrast, the beta-lactamase with a pI value of 4.5 showed relatively greater cephalosporinase activity. An open reading frame in cosmid Y49 of the DNA library of M. tuberculosis H37Rv with homology to known class A beta-lactamases was amplified from chromosomal DNA of M. tuberculosis H37Ra by PCR and was overexpressed in Escherichia coli. The recombinant enzyme was kinetically similar to the pI 5.1 and 4.9 enzymes purified directly from M. tuberculosis. It exhibited predominant penicillinase activity and was especially active against azlocillin. It was inhibited by clavulanic acid and m-aminophenylboronic acid but not by EDTA. We conclude that the major beta-lactamase of M. tuberculosis is a class A beta-lactamase with predominant penicillinase activity. A second, minor beta-lactamase with relatively greater cephalosporinase activity is also present.     

Attitudes toward aging and towards the needs of older people

In order to explore the underlying dimensionality of beliefs about aging, two sets of opinion statements (one dealing with general attitudes toward aging and the other with programmatic issues) were factor analyzed for two age groups: persons under 60 (N = 290) and persons 60 and older (N = 181). For the first set of social-psychological belief statements, a common factor structure was found for the two age groups. For the second set of programmatic statements, there was some communality between age groups, but most of the items loading on the factors tended to be age-specific. The belief structure of the older group was generally more complex and variegated than was the case with the younger group. Except where the items were personal relevance, positive and negative items tended to load on separate, unipolar factors.     

Changes of erythrocyte membrane lipids in ethanol induced hyperlipidemia (Zieve's syndrome) (author's transl)

In 11 patients with alcohol-induced hyperlipemia, of whom 6 showed a Zieve Syndrome increased phospholipids, triglycerides and total cholesterol were found in the red cells stromal. The gasliquid chromatographic analysis of the phospholipid fatty acids showed increased contents of saturated and monounsaturated fatty acids C 16-C 18 smaller contents of longchain highly unsaturated fatty acids. The changes in the fatty acid pattern mainly occurred in patients with Zieve Syndrome and could be important for the mechanism of the hemolytic anemia. Theses findings could be in connexion with vitamin E deficiency.     

Bubble rupture in a vibrated liquid under microgravity

The response of an air bubble surrounded by a liquid in a sealed cell submitted to vibrations was investigated experimentally under microgravity conditions and compared to experiments under normal gravity conditions. As in normal gravity [1], it was observed that the bubble split into smaller parts when the acceleration of the vibrations reached a threshold. This threshold in microgravity is substantially smaller than that in normal gravity. Experimental results are presented in terms of an acceleration based Bond number which has been found to characterize the bubble behaviour in the laboratory experiments [1].