Singular Value Decomposition of the Radial Distribution Function for Hard Sphere and Square Well Potentials

We compute the singular value decomposition of the radial distribution function for hard sphere, and square well solutions. We find that decomposes into a small set of basis vectors allowing for an extremely accurate representation at all interpolated densities and potential strengths. In addition, we find that the coefficient vectors describing the magnitude of each basis vector are well described by a low-order polynomial. We provide a program to calculate in this compact representation for the investigated parameter range.     

Sequence of the halobacterial glycosaminoglycan

The cell-surface glycoprotein of halobacterium contains a sulfated repeating unit saccharide chain, similar to the mammalian glycosaminoglycans. The composition of a presumptive repeating pentasaccharide unit of this glycosaminoglycan is 1 GlcNAc, 1 GalNAc, 1 Gal, 1 GalA (where GalA represents galacturonic acid), 1 3-O-methyl-GalA, and 2 SO42-. Linkage to protein of this glycoconjugate involves the hitherto unique unit Asn-GalNAc, with the N-linked asparagine residue being the second NH2-terminal amino acid and part of the common N-linked glycosyl acceptor sequence Asn-X-Thr(Ser). Transfer of the completed, sulfated glycosaminoglycan from its lipid precursor to the protein occurs at the cell surface, and the presence of this sulfated saccharide chain in the cell-surface glycoprotein seems to be required to maintain the structural integrity of the rod-shaped halobacteria. In this paper, we report the complete saccharide structure of this N-linked glycosaminoglycan. This structure is deduced from chemical analyses of fragments that were isolated after hydrazinolysis and subsequent nitrous acid deamination or after mild acidic hydrolysis of purified Pronase-derived glycosaminoglycan-peptides. The halobacterial glycosaminoglycan consists, on the average, of 10 repeating pentasaccharide units of the following structure. (formula: see text) The reducing end N-acetylgalactosamine residue is linked directly to the asparagine, without a special saccharide linker region.     

Suppression of anti-mouse immunoglobulin antibodies in subhuman primates receiving murine monoclonal antibodies against T cell antigens

Murine monoclonal antibodies stimulate the production of human anti-mouse immunoglobulin antibodies (AMIA) when administered to patients. This limits their long-term usefulness as therapeutic and diagnostic agents. We report the use of three maneuvers to suppress AMIA against T cell-specific monoclonal antibodies in cynomolgus monkeys. Twelve monkeys received daily i.v. infusions of 1 mg each of anti-Leu-2a, -3a, and -5 on days 1 through 10. One group (control) received no suppressive regimen. The second group received cyclosporine, 12.5 mg/kg daily on days -7 to +14. The third group (PI) were passively immunized with 0.4 ml of hyperimmune monkey AMIA serum on days -7, -1, 2, 4, 6, and 8. The fourth group (TLI) received 1700 rad fractionated total lymphoid irradiation ending on day -1. The animals treated with TLI were markedly delayed in the onset of AMIA, which was suppressed to less than 1% of the control group. The AMIA specific for the constant region of animals receiving PI was also suppressed to one-third of control. The majority of the AMIA in all the animals was anti-idiotypic and wholly anti-idiotypic in the TLI animals.     

Endocytosis of a small dermatan sulphate proteoglycan. Identification of binding proteins.

Endosomal preparations from human osteosarcoma cells and from fibroblasts contain 51,000- and 26,000-Mr proteins which bind a small dermatan sulphate proteoglycan after SDS/polyacrylamide-gel electrophoresis and Western blotting. Binding can be inhibited by unlabelled proteoglycan core protein. The proteins co-precipitate with a proteoglycan core protein-antibody complex. Scatchard analysis of immobilized endosomal proteins yielded a KD of about 37 nM for the proteoglycan. In intact cells proteins of the same size can be found. They are sensitive to trypsinization. A 51,000-Mr protein is the predominant membrane protein with strong binding to immobilized dermatan sulphate proteoglycan. There are additional proteoglycan-binding proteins with Mr values of around 30,000 and 14,000 which are insensitive to trypsin treatment. In contrast with the 51,000- and 26,000-Mr proteins, they resist deoxycholate/Triton X-100 extraction several days after subcultivation.     

Light- and Scanning Electron Microscopic Studies on the Development of the Mycoparasite Verticillium psalliotae Treschow on Uredospores of the Soybean Rust (Phakopsora pachyrhizi Syd.)

Abstract By light and scanning electron microscopy it is shown that a strain of Verticillium psalliotae , originally isolated from pustules of the soybean rust in Thailand, is able to infect uredospores of this rust fungus. In most cases appressoria-like structures were formed at the infection sites. However, only a part of the spores were infected. Most spores appeared heavily damaged without any visible mycelium inside. This indicates that growth of Verticillium psalliotae on uredospores of the soybean rust is probably mainly based on the production of lytic enzymes.     

F0 part of the ATP synthase from Escherichia coli. Influence of subunits a, and b, on the structure of subunit c

Four different sets of proteoliposomes were prepared from F0, subunit c, a complex of subunits a and c (ac complex) and an ac complex supplemented with subunit b. Only liposomes containing intact F0 or all subunits of F0 were active in proton translocation and F1 binding [Schneider, E. and Altendorf, K. (1985) EMBO J. 4, 515-518]. The conformation of subunit c in the different preparations was analyzed by labelling the proteoliposomes with the hydrophobic photoactivatable reagent 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID). Subsequent isolation and Edman degradation of this polypeptide revealed distinct radioactive labelling patterns over the entire amino acid sequence. In the F0 complex and in the ac complex subunit c retains a labelling pattern which is related to that found in TID-labelled membrane vesicles of Escherichia coli [Hoppe et al. (1984) Biochemistry 23, 5610-5616]. In the absence of subunit a, considerably more and different amino acid residues of subunit c are modified. The labelling data are discussed in relation to structural aspects of F0 and functional properties of proteoliposomes reconstituted with F0 or individual subunits.     

Ethanol stimulates formation of leukotriene C4 in rat gastric mucosa

Ethanol-induced gastric mucosal damage is characterized by microcirculatory changes such as statis and plasma leakage. Sluggish blood flow and statis have also been observed after administration of exogenous leukotriene (LT) C₄. The effect of ethanol on the release of LTC₄ from rat gastric mucosa was therefore investigated. It was found that intragastric instillation of ethanol increases gastric mucosal release of LTC₄ in a dose- and time-dependent manner parallel to the production of gastric lesions. The lipoxugenase inhibitor nordihydroguaiaretic acid (NDGA) and the anti-ulcer drug carbenoxolone (CX) inhibited mucosal release of LTC₄ and simultaneously protected against gastric damage caused by ethanol. It is concluded that increased formation of LTC₄ and /or other 5-lipoxygenase-derived products of arachidonate metabolism may be involved in ethanol-induced gastric damage. Furthermore, inhibition of the 5-lipoxygenase pathway may be an important mechanism of action of gastric protective drugs.     

Limited nonenzymatic glucosylation of low-density lipoprotein does not alter its catabolism in tissue culture

This study examines the effects of various degrees of chemical modification of low-density lipoprotein (LDL) on its catabolism by various cell types. Moderate glucosylation of LDL does not alter its interaction with the high-affinity receptor present on human fibroblasts at concentration of 5-2000 micrograms LDL-cholesterol/ml. Only heavily glucosylated LDL (more than 12 lysine residues glucosylated per apolipoprotein B) or LDL glucosylated in the presence of Na(CN)BH3, i.e., conditions not expected to occur in diabetes, inhibit receptor-mediated internalisation and degradation. Moderately glucosylated LDL is also readily recognized by cultured rat hepatocytes and porcine endothelial cells. Human monocyte-derived macrophages accumulate cholesteryl ester when incubated with acetylated LDL for 12 days but no enhanced cholesteryl ester formation was found when native or glucosylated LDL (3.3 lysines glucosylated per apolipoprotein B) were used.