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Biomedical subjects

G Jung

Publications and source records attributed to G Jung.

At least 433 records · Page 24Linked to original sources
PubMed1989

Enhancement of protection against Salmonella infection in mice mediated by a synthetic lipopeptide analogue of bacterial lipoprotein in S. typhimurium vaccines.

Vaccines consisting of acetone-killed Salmonella typhimurium were supplemented with a synthetically prepared lipopeptide derivative of bacterial lipoprotein, Pam3Cys-Ser-Ser-Asn-Ala. NMRI mice were immunized with these vaccines, receiving two intraperitoneal injections and were challenged intraperitoneally with graded doses of S. typhimurium C5. The protective capacity of the supplemented vaccines was compared with that of the unsupplemented bacterial vaccine, and with the effectiveness of the supplementing component alone. The LD50 served as a criterion for protective capacity. The results showed that 90% of the S. typhimurium S-form vaccine could be replaced by the adjuvant lipopeptide without a recognizable decrease in protective immunizing capacity. A similar but less pronounced enhancement of protection was obtained with a R-mutant vaccine supplemented with the lipopeptide; by supplementing the standard vaccine dose with lipopeptide an increase in protection was also achieved. Lipopeptide alone was not effective in protecting mice from infection with S. typhimurium.

Adjuvants, Immunologic↗
PubMed1989

Dictyostelium discoideum contains a gene encoding a myosin I heavy chain.

We have cloned and completely sequenced a gene encoding the heavy chain of Dictyostelium myosin I. Like the myosin I molecules from Acanthamoeba, the Dictyostelium myosin I heavy chain is composed of a globular head domain fused to a 45-kDa glycine-, proline-, and alanine-rich carboxyl-terminal domain, rather than the coiled-coil rod domain of conventional myosins. Comparisons of the Dictyostelium myosin I heavy-chain amino acid sequence with those of the Acanthamoeba myosins I reveal that they are highly similar throughout, including the unconventional carboxyl-terminal domains. The Dictyostelium myosin I gene is expressed in growing cells as a 3600-nucleotide mRNA. Measurements of the steady-state level of this mRNA at different times during starvation-induced aggregation and development are consistent with a role for myosin I in chemotaxis and aggregation. Generation of Dictyostelium cells lacking myosin I by gene disruption and/or antisense RNA production should provide a way to test directly the role of this nonfilamentous myosin in cell motility. These experiments will be simplified by the fact that Southern blot analyses of Dictyostelium genomic DNA are consistent with there being a single myosin I heavy-chain gene.

Amino Acid Sequence↗
PubMed1989

Lipopeptide derivatives of bacterial lipoprotein constitute potent immune adjuvants combined with or covalently coupled to antigen or hapten.

Lipopeptide analogues of the N-terminus of bacterial lipoprotein consisting of N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteine (Pam3Cys) attached to one to five further amino acids [Pam3Cys-Ser-Ser-Asn-Ala, Pam3Cys-Ser-(Lys)4, Pam3Cys-Ala-Gly, and Pam3Cys-Ser] were investigated for biological activity. In vitro, the compounds proved to be potent activators for Balb/c splenocytes as determined by proliferation assays. When given in vivo in combination with SRBC, Pam3Cys-Ser and Pam3Cys-Ala-Gly acted as immunoadjuvants enhancing the antigen specific IgM response after 7, and the IgG response after 14 days. In combination with dinitrophenylated bovine serum albumin (BSA(Dnp)), especially the amphiphilic and water-soluble lipohexapeptide Pam3Cys-Ser-(Lys)4 constituted a potent immune adjuvant. The lipopeptide was able to fully replace Freund's complete adjuvant (FCS) enhancing both anti-Dnp IgM and IgG in Balb/c mice. The hapten Dnp was also coupled directly--or via the spacer molecule 1,6-diaminohexane (HMD)--to the synthetic lipopeptides. The chemically defined low-molecular-mass conjugates obtained were capable of inducing anti-hapten-specific IgM and IgG without further adjuvants or carriers. The anti-hapten responses induced by these chemically uniform lipopeptide-hapten conjugates were, however, less pronounced than the response to the conventional heterogeneous hapten-protein conjugate BSA(Dnp), and only a weak boost effect was observed. Our results show that defined lipopeptides are novel immunoadjuvants either combined with or covalently linked to antigens or haptens.

Adjuvants, Immunologic↗
PubMed1989

Induction of tumor cytotoxicity in murine bone marrow-derived macrophages by two synthetic lipopeptide analogues.

Lipoprotein from the outer membrane of Escherichia coli and the synthetically prepared lipopeptides Pam3Cys-Ala-Gly and Pam3Cys-Ser-[Lys]4 derived from the N-terminus of lipoprotein constitute potent macrophage and polyclonal B-lymphocyte activators. The compounds have also been shown to induce tumor cytotoxicity in murine bone marrow-derived macrophages (BMDM). Bone marrow stem cells were cultured in the presence of colony-stimulating factor 1 to yield BMDM of 98 to 99% purity at day 8. After stimulation with the lipopeptides on days 4, 6, 8 and 10 of bone marrow culture, the cytotoxic effect of BMDM on the tumor cell line L929 was determined in a [3H]thymidine release assay. Maximum tumor cytotoxicity was found on day 8 with an optimal effector/target-cell ratio of 10:1, and a duration of lipopeptide stimulation of 4 h. The supernatants of lipopeptide stimulated BMDM also showed cytotoxic activity that could be inhibited by antiserum against tumor necrosis factor alpha. The effects of the lipopeptides Pam3Cys-Ala-Gly and Pam3Cys-Ser-[Lys]4 were comparable or superior to those exerted by lipopolysaccharide. Our results demonstrate that synthetic lipopeptides are potent activators for murine BMDM and may therefore prove to be an important tool for the elucidation of the role of macrophages in the host defence mechanisms against tumor cells.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1989

Specific antibody response towards predicted epitopes of the epidermal growth factor receptor induced by a thermostable synthetic peptide adjuvant conjugate.

Applying computer-assisted epitope prediction to the amino-acid sequence of the epidermal growth factor receptor (EGFR), the extracytoplasmic domain EGFR(516-529) was selected as a putative antigenic region. EGFR(516-529) was synthesized on a solid-phase matrix and N-terminally linked to the low mol. wt adjuvant tripalmitoyl-S-glyceryl-cysteinyl-serine (Pam3 Cys-Ser). The conjugation to this B cell and macrophage-activating lipopeptide considerably enhanced the immunogenicity of the EGFR peptide. Using the conjugate Pam3 Cys-Ser-EGFR(516-529), a peptide-specific monoclonal antibody was produced. By flow cytometry and immunoprecipitation the antibody was demonstrated to recognize EGFR on A431 cells, expressing large numbers of EGFR. With this novel approach synthetic immunogens can be prepared which could serve as thermostable synthetic vaccines with great potential in countries where a functional cold chain cannot be maintained.

Adjuvants, Immunologic↗
PubMed1989

[Prevention of radiation injuries of the small intestine with pelvic exclusion by polyglactin 910 mesh. Contribution to gynecologic and digestive cancer surgery].

Used in 13 cases of advanced gynecological and gastrointestinal carcinoma, pelvic exclusion using a suspension of the small intestine above the pelvis using absorbable material. The low-level of morbidity, value in dosimetric estimation, perfect feasibility and low cost of this technique should lead to its more widespread use whilst strictly respecting its indications. Nuclear magnetic resonance has been found to be a particularity novel and valuable method of post-operative investigation in visualisation and assessment of resorption of the polyglactine 910 trellis. Results in this series are analyzed at the end of a 5 to 14 month follow-up period and compared with data from experimental and clinical studies in the recent world literature.

Adult↗
PubMed1988

Gallidermin: a new lanthionine-containing polypeptide antibiotic.

Gallidermin is a new member of the class of lanthionine-containing peptide antibiotics, which are summarized under the common name lantibiotics. The lantibiotic gallidermin is produced by Staphylococcus gallinarum (F16/P57) Tü3928, and it exhibits activities against the Propionibacteria, involved in acne disease. Gallidermin differs from the recently discovered tetracyclic 21-residue peptide antibiotic epidermin only in a Leu/Ile exchange in position 6. The isolation procedures for gallidermin included adsorption directly from the culture broth, ion-exchange chromatography of the amphiphilic and basic polypeptide followed by desalting, and final purification by reversed-phase HPLC. The structural elucidation of the polypeptide containing four thioether bridges involved mainly a combination of automated gas-phase sequencing, thermospray liquid chromatography/mass spectrometry and fast-atom-bombardment mass spectrometry.

Alanine↗
PubMed1988

Prepeptide sequence of epidermin, a ribosomally synthesized antibiotic with four sulphide-rings.

The genetic basis for the biosynthesis of large polypeptide antibiotics such as nisin has not been explained so far. We show here that the structural gene epiA encoding the antibiotic epidermin from Staphylococcus epidermidis is located on a 54-kilobase plasmid and codes for a 52-amino-acid prepeptide, which is processed to the tetracyclic 21-peptide amide antibiotic. The mature sequence of epidermin corresponds to the C-terminal 22-peptide segment of pre-epidermin and contains the precursor amino acids Ser, Thr and Cys, from which the unusual amino-acid constituents are derived. The more lipophilic epidermin is cleaved at a hydrophilic turn between Arg-1 and Ile+1 from the N-terminal segment-30 to -1, which probably assumes a partially amphiphilic alpha-helix conformation. We propose that the N-terminus (-30 to -1) plays a cooperative role during modification reactions and prevents toxicity of the mature epidermin to the producing strain before the antibiotic is cleaved off and secreted.

Amino Acid Sequence↗
PubMed1988

Structure-function studies on Acanthamoeba myosins IA, IB, and II.

Myosins IA and IB are globular proteins with only a single, short (for myosins) heavy chain (140,000 and 125,000 daltons for IA and IB, respectively) and are unable to form bipolar filaments. The amino acid sequence of IB heavy chain shows 55% similarity to muscle myosins in the N-terminal 670 residues, which contain the active sites, and a unique 500-residue C-terminus highly enriched in proline, glycine, and alanine. The C-terminal region contains a second actin-binding site which allows myosins IA and IB to cross-link actin filaments and support contractile activity. Myosins IA and IB are regulated solely by phosphorylation of one serine on the heavy chain positioned between the catalytic site and the actin-binding site that activates ATPase. Myosin II is a more conventional myosin in composition (two heavy chains and two pairs of light chains), heavy chain sequence (globular head 45% identical to muscle myosins and a coiled-coil helical tail), and structure (bipolar filaments). The tail of myosin II is much shorter than that of other conventional myosins, and it contains a 25 amino acid sequence in which helical structure is predicted to be weak or absent. The position of this sequence corresponds to the position of a bend in the monomer. Myosin II heavy chains also have a 29-residue nonhelical tailpiece which contains three regulatory, phosphorylatable serines. Phosphorylation at the tip of the tail regulates ATPase activity in the globular head apparently through an effect on filament structure.

Acanthamoeba↗
PubMed1988

High-performance liquid chromatography of siderophores from fungi.

A reversed-phase HPLC separation of iron(III) chelates of 16 representative fungal siderophores including ferrichromes, coprogens and triacetylfusarinine C was established in order to investigate siderophore production of fungi. For comparison purposes, the widely used bacterial siderophore ferrioxamine B was included. Culture filtrates of the fungi Penicillium resticulosum, Fusarium dimerum, Aspergillus fumigatus and Neurospora crassa were quantitatively analyzed for the presence of known and unknown siderophores after growth in low-iron culture media and adsorption on XAD-2 columns using this HPLC separation system. Photodiode array detection allowed the distinction between siderophores and non-siderophores. According to their ultraviolet/visible spectra, a further classification of the siderophores into four types due to the number of anhydromevalonic acid residues per molecule (0-3) was possible.

Aspergillus fumigatus↗
PubMed1988

Characterization of ferrioxamine E as the principal siderophore of Erwinia herbicola (Enterobacter agglomerans).

Several strains of the enterobacterial group Erwinia herbicola (Enterobacter agglomerans) were screened for siderophore production. After 3 days of growth in a low-iron medium, all strains studied produced hydroxamate siderophores. The retention values of the main siderophore during thin-layer chromatography on silica gel plates and on HPLC reversed-phase columns were identical with those of an authentic sample of ferrioxamine E (norcardamine). Gas-chromatographic analysis of the HI hydrolyzate yielded succinic acid and 1,5-diaminopentane in equimolar amounts; fast-atom-bombardment (FAB) mass spectroscopy showed a molecular mass of 653 Da. Iron from 55Fe-labelled ferrioxamine E was well taken up by iron-starved cells of E. herbicola (Km = 0.1 microM, Vmax = 8 pmol mg-1 min-1). However, besides ferrioxamine E (100%), several exogenous siderophores such as enterobactin (94.5%), ferric citrate (78.5%), coprogen (63.5%) and ferrichrome (17.5%) served as siderophores, suggesting the presence of multiple siderophore receptors in the outer membrane of E. herbicola.

Biological Transport, Active↗
PubMed1988

Distinction between HIV-1 and HIV-2 infection using novel synthetic lipopeptide conjugates as antigens in enzyme immunoassays.

A novel immunoassay technique using synthetic lipopeptide (Pam3Cys-Ser) linked to immunodominant peptide domains of HIV-1 and HIV-2 envelope proteins as an antigen adsorbent has been developed. Attachment of peptides to microtiter plates can be considerably improved with this method by employing the hydrophobic properties of lipopeptide. From the sera of 121 HIV-1 infected patients 117 reacted with Pam3Cys-Ser-[HIV-1(598-609)cyclic disulfide]. Five of 5 HIV-2 positive sera were positive with Pam3Cys-Ser-[HIV-2(593-603)cyclic disulfide]. Control sera failed to react with these conjugates.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Stimulation of human and murine adherent cells by bacterial lipoprotein and synthetic lipopeptide analogues.

Lipoprotein from the outer membrane of Escherichia coli and its synthetically prepared N-terminal lipopeptide segments Pam3Cys-Ser-Ser-Asn-Ala and Pam3Cys-Ser, as well as lipoprotein from other Enterobacteriaceae, constitute potent polyclonal B lymphocyte activators. Here, we demonstrate that these compounds were also able to stimulate human and murine leukocytes: in murine macrophages, we could show the induction of interleukin 1 release by the mitogens, as measured in the thymocyte proliferation assay. Moreover, murine peritoneal exudate cells were stimulated to secrete prostaglandins E2 (PGE2) and F2 alpha (PGF2 alpha). The effect of Pam3Cys-Ser on the murine macrophage cell line P388D1 was also tested: the compound induced an increase in proliferation, as measured by a thymidine incorporation assay. In addition, the cell line could be induced to release IL 1 into the supernatant. Correspondingly, induction of IL 1 release could also be demonstrated in human mononuclear cells. Our results demonstrate that the two novel synthetic lipopeptides are potent stimulators for human monocytes and murine macrophages. These findings may be important for the elucidation of the role of these bacterial surface components in the course of bacterial infections.

Animals↗
PubMed1988

Phosphatidylinositol metabolism and protein kinase C activation in leukocytes by lipopeptides.

The synthetic lipopeptide Pam3Cys-Ser-Ser-Asn-Ala, an analogue of the N-terminal part of bacterial lipoprotein, constitutes a potent macrophage and B lymphocyte activator. In the macrophage cell-line P388D1 Pam3Cys-Ser-Ser-Asn-Ala stimulated phosphoinositol turnover, whereas in small resting lymphocytes no enhanced turnover was observed. Upon lipopeptide stimulation, a translocation of PKC from the cytosol to the plasma membrane was found in the cell line P388D1 but not in lymphocytes. Substituting lipopeptide for diacylglycerol shows that Pam3Cys-Ser-Ser-Asn-Ala leads to an activation of protein kinase C at Ca2+ concentrations of 0.5 mM. Thus, mitogenic lipopeptides constitute novel tools for investigating the molecular mechanism of transmembrane signaling in leukocyte activation.

Animals↗
PubMed1988

Structural fluctuations of a helical polypeptide traversing a lipid bilayer.

Time-resolved fluorescence anisotropy (FA) measurements are reported for five helical bilayer-spanning henicosapeptides, each containing one tryptophan at sequence position 1, 6, 11, 16, or 21. The FA decay reflects two molecular processes in all cases: local internal fluctuations of the tryptophan side chain with a relaxation time of 200-500 ps, and motions of the whole polypeptide molecule with a relaxation time of 9-10 ns. The amplitudes of the fast fluctuation are largest at the helix ends and decrease toward the center of the helix. A similar observation was made for the helical polypeptides dissolved in organic solvents showing that the mobility gradient along the polypeptide sequence is an inherent property of the polypeptide helix and not due to the lipid bilayer. However, the amplitudes of the fast fluctuations can be modulated by the physical state of the lipid bilayer. With decreasing temperature, the internal mobility of the tryptophan in all positions decreases with an abrupt change at the lipid-phase transition. Concomitant molecular dynamics calculations indicate a correlation between the fast FA decay and conformational fluctuations within the helix. According to the simulation, the conformation of the polypeptide is on average predominantly helical, but actually the molecule can fluctuate between a variety of different substructures. The conformational fluctuations are largest at the helix ends and provide the free space required for rotation of the indole ring around the tryptophan side chain bonds.

Amino Acid Sequence↗