Coliform inhibition by bacteriocin-like substances in drinking water distribution systems

Bacterial isolates from an unchlorinated potable groundwater system and a chlorinated surface water system were screened by an agar overlay method for the ability to produce bacteriocin-like substances (BLS) inhibitory to the growth of Escherichia coli, Klebsiella sp., and Enterobacter aerogenes. The production of coliform-specific BLS by noncoliform bacteria varied with the site and date of isolation as well as the genus of the producer strain. A total of 448 bacterial isolates were screened from the chlorinated system, and 22.1% produced BLS specific for at least one of the three coliforms. In the unchlorinated system, 7.9% (n = 696) possessed this ability. Flavobacterium/Moraxella comprised 57.1% of all bacteria (from both systems) producing BLS. The possibility that BLS interfere with coliform detection in standard bacteriological water quality tests is discussed.     

A new suction device for microsurgery

A new suction device for microsurgical procedures is presented. This device is made of soft, compliant PVC, which enables all fluids to be evacuated from the surgical field without damaging the surrounding soft tissue. The device is designed with front and radial ports that allow placement onto the blood vessel or nerve while the anastomosis is being performed. There is a tapered end providing the surgeon with fine control of the suction. Unlike other bulky suction devices, this one readily fits into the operative field without inhibiting operative procedures. It also readily fits varying sizes of conventional Frazier-type tips. The device has been used in over 100 microsurgical procedures and it has served well.     

Network management as a strategy

Teleprocessing users require reliability, which implies network control and diagnosis. Three levels of control are identified and described: technical control, network control and network management. The advantages of the latter are discussed in terms of an integrated design strategy.     

The P9 pocket of HLA-DQ2 (non-Aspbeta57) has no particular preference for negatively charged anchor residues found in other type 1 diabetes-predisposing non-Aspbeta57 MHC class II molecules

Susceptibility and resistance to type 1 diabetes are associated with MHC class II alleles that carry non-Asp and Asp at residue 57 of their beta chain respectively. The effect of Asp or non-Aspbeta57 may relate to a differential ability of distinct class II molecules to bind specific immuno-pathogenic peptides. Recent studies in man and mouse have revealed that some type 1 diabetes-predisposing non-Aspbeta57 class II molecules (i.e. DQ8, DR4Dw15 and I-Ag7) preferentially bind peptides with a negatively charged anchor residue at P9. It has been suggested that this is a common feature of type 1 diabetes-predisposing class II molecules. The molecular explanation for such a phenomenon could be that class II beta chains with Aspbeta57 form a salt bridge between Aspbeta57 and a conserved Arg of the a chain, whereas in non-Aspbeta57 molecules the Arg is unopposed and free to interact with negatively charged P9 peptide anchor residues. We have investigated the specificity of the P9 pocket of the type 1 diabetes-associated DQ2 molecule and in particular examined for charge effects at this anchor position. Different approaches were undertaken. We analyzed binding of a high-affinity binding ligand and P9-substituted variants of this peptide, and we analyzed the binding of a set of synthetic random peptide libraries. The binding analyses were performed with wild-type DQ2 and a mutated DQ2 with Ala at beta57 substituted with Asp. Our results indicate that the wild-type DQ2 (non-Aspbeta57) prefers large hydrophobic residues at P9 and that there is no particular preference for binding peptides with negatively charged residues at this position. The specificity of the P9 pocket in the mutated DQ molecule is altered, indicating that the beta57 residue contributes to determining the specificity of the P9 pocket. Our data do not lend support to the hypothesis that all non-Asp beta57 class II molecules predispose to development of disease by binding peptides with negatively charged P9 anchor residues.     

Synthesis of 2-isoxazoline and alpha-hydroxy ketomethylene dipeptide isosteres

We have developed a simple and stereoselective method for synthesizing novel dipeptide isosteres using nitrile oxide cycloaddition as a key reaction. Employing this method, we have prepared efficiently various peptidomimetics containing 2-isoxazolines and alpha-hydroxy ketomethylene dipeptide isosteres.     

Congenital dislocation of the patella

In 8 congenital patellar dislocations, in 7 patients, the patella was permanently and laterally dislocated, and irreducible or difficult to reduce. The patella usually was hypoplastic and showed absent facets. The intercondylar groove of the femur also was underdeveloped. In all but one patient, knee function was improved by a surgical procudure which involved lateral release of ptella, medial transpositon of patellar tendon, and plication of medial capsule or advancement of vastus medialis.