[Infant nutrition in East Germany].
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Breast Feeding↗
Biomedical subjects
G Jung
Publications and source records attributed to G Jung.
Identification of the polypeptide encoded by the URF-1 gene of Neurospora crassa mtDNA.
Two peptides, potentially representing antigenic determinants of a proposed gene product, were synthesized. The peptide sequences were deduced from the nucleotide sequence of the unidentified reading frame (URF)1 of the Neurospora crassa mitochondrial genome. Specific antisera to the synthetic peptides were produced. The antibodies recognized a single polypeptide species with an apparent relative molecular mass of about 30 000. The mitochondrial origin of this polypeptide was verified by in vivo labelling experiments in the presence of cycloheximide, as well as by in vitro translation using isolated mitochondria. The chemical identification of the protein was performed by partial radiosequencing of the N-terminal portion of the immunoprecipitated URF-1 product. The amount of URF-1 polypeptide present in N. crassa mitochondria is in the range of 1-2%. The protein is a constituent of the inner envelope of the organelle and probably part of a more complex membrane unit.
Amino Acid Sequence↗
Oxygenation of phosphatidylcholine by human polymorphonuclear leukocyte 15-lipoxygenase.
A cell-free human polymorphonuclear leukocyte preparation containing both 15- and 5-lipoxygenase activities was found to oxygenate phosphatidylcholine at carbon-15 of the arachidonic acid moiety. No oxygenation at carbon-5 was found. Under similar incubation conditions, soybean and rabbit reticulocyte 15-lipoxygenases also oxygenated phosphatidylcholine, whereas rat basophilic leukemia cell 5-lipoxygenase, rabbit platelet 12-lipoxygenase and rat liver cytochrome P-450 preparations did not. Our results suggest that the oxygenation of phospholipids may be a unique property of the 15-lipoxygenases.
Animals↗
Trichotoxin A40. Purification by counter-current distribution and sequencing of isolated fragments.
The isolation of the membrane-modifying polypeptide antibiotics from the mycelium of Trichoderma viride 5242 was optimized via extraction with dichloromethane and chromatography on Sephadex LH-20. The components trichotoxin A40 and A50 were separated from each other and purified by multiplicative counter-current distribution. The sequence of proteinase-resistant trichotoxin A40 was determined by combined gas chromatography and mass spectrometry of three isolated N-acetylated dodecapeptides and two N-prolylhexapeptides obtained after selective trifluoroacetolysis. Including amino acid exchanges due to natural microheterogeneity, the sequence is Ac-Aib-Gly(LAla)-Aib-LLeu-Aib-LGln-Aib-Aib-Aib(LAla )-LAla-Aib-Aib-LPro-LLeu -Aib-DIva(Aib)-LGlu-LValol. In contrast to the eicosapeptide alamethicin, trichotoxin A40 contains only 18 residues, with a higher proportion of alpha-aminoisobutyric acid (Aib), C-terminal L-valinol (Vol), one D-isovaline (Iva) and no proline at the N-terminal part.
Amino Acid Sequence↗
Actin-associated cell-surface glycoprotein from ascites cell microvilli: a disulfide-linked multimer.
Isolated microvilli of the MAT-C1 subline of the 13762 rat mammary adenocarcinoma contain a transmembrane complex composed of a cell surface, cytoskeleton-associated glycoprotein (CAG), actin, and a 58,000-dalton polypeptide (58K). The behavior of CAG has been studied by differential centrifugation and velocity sedimentation gradient centrifugation of detergent extracts of microvilli. CAG can be pelleted along with a fraction of the microvillar actin even in the presence of ionic detergents and under microfilament-depolymerizing conditions. By velocity sedimentation analysis CAG in Triton/PBS extracts sediments as a large, heterogeneous species (sedimentation coefficient greater than 25S). In Sarkosyl and sodium dodecyl sulfate (SDS) the size and heterogeneity are somewhat reduced. In SDS CAG sediments as a 20S species in the absence of mercaptoethanol and as a 5S species in the presence of mercaptoethanol. These results indicate that CAG is a disulfide-linked multimer in the microvillus membrane. We suggest that the stable multimeric structure of CAG permits it to act as the membrane association site for several microfilaments and plays an important role in the formation and stabilization of the microvillus structure.
Actins↗
Molecular shape and dipole moment of alamethicin-like synthetic peptides.
The peptides Boc-(L-Ala-Aib-L-Ala-Aib-L-Ala)n-OMe, with n = 2 (P10) and n = 4 (P20), have been synthesized as purely hydrophobic models of the antibiotic alamethicin, which is known to be a voltage-dependent pore former in membranes and is apparently alpha-helical in lipophilic media. These peptides were investigated in 1-octanol, a solvent which resembles the membrane environment. From dielectric dispersion studies quantitative information on the molecular shape and dipole moments could be derived. Further independent data concerning conformation and extent of aggregation of the peptides were obtained by circular dichroism and ultracentrifuge measurements. The results suggest that the peptides assume the form of elongated particles having a significant amount of ordered secondary structure and carrying a dipole parallel to the long axis. Apparently the monomeric peptide molecules undergo, to some extent, a head-to-tail aggregation which is slightly enhanced at lower temperatures. Based on the high-frequency parts of the dielectric dispersion curves the lengths, diameters, and dipole moments of the monomer particles have been determined as 22.5A, 10A, 36 D (P10) and 28.5A, 12A, 64D (P20).
Alamethicin↗
Isolation of microvillar microfilaments and associated transmembrane complex from ascites tumor cell microvilli.
The association of microvillar microfilaments with the microvillar membrane actin-containing transmembrane complex of MAT-C1 13762 ascites tumor cell microvilli has been investigated by differential centrifugation, gel electrophoresis and electron microscopy of detergent extracts of the isolated microvilli. Several methods have been used to reduce breakdown and solubilization of the microfilament core actin during the detergent extractions for preparation of microvillar core microfilaments. Gel electrophoresis of differential centrifugation fractions demonstrated that over 70% of the total microvillus actin could be pelleted with microfilament cores at 10 000 g under extraction conditions which reduce filament breakdown. Transmission electron microscopy (TEM) of all of the core preparations showed arrays of microfilaments and small microfilament bundles. The major protein components of the microfilament cores, observed by sodium dodecyl sulfate (SDS) electrophoresis, were actin and alpha-actinin. Among the less prominent polypeptide components was a 58 000 Dalton polypeptide (58 K), previously identified as a member of the MAT-Cl transmembrane complex. This three-component complex contains, in addition to 58 K, actin associated directly and stably with a cell surface glycoprotein (Carraway, CAC, Jung, G & Carraway, K L, Proc. natl acad. sci. US 80 (1983) 430). Evidence that the apparent association of complex with the microfilament core was not due simply to co-sedimentation was provided by myosin affinity precipitation. These results provide further evidence that the transmembrane complex is a site for the interaction of microfilaments with the microvillar plasma membrane.
Actins↗
Specific antibodies elicited by antigen covalently linked to a synthetic adjuvant.
S-(2,3-Bis(palmitoyloxy)-(2RS)-propyl)-N-palmitoyl-(R)-cysteinyl-( S)-serine (Tripam-Cys-Ser), a synthetic analogue of the N-terminal part of bacterial lipoprotein, constitutes a potent B-lymphocyte activator, inducing mitosis and immunoglobulin production, and is an adjuvant of the humoral immune response. The product was covalently coupled to a nonimmunogenic oligopeptide, representing an extracytoplasmic sequence of the receptor for the epidermal growth factor (EGF-R amino acids 516-529: Asn-Leu-Leu-Glu-Gly-Glu-Pro-Arg-Glu-Phe-Val-Glu-Asn-Ser). The resulting conjugate was able to induce a specific antibody response 2 wk after a single i.p. administration in mice, as measured by ELISA assays. Controls performed by injecting either adjuvant or oligopeptide alone, or a mixture of both compounds, elicited only a marginal stimulation of the specific antibody response. The conjugate was also immunogenic in vitro. Synthetically derived lipopeptides, thus, constitute powerful agents for turning substances of low immunogenicity into potent immunogens, after conjugating them covalently to the adjuvants. This technique should have a wide application in the preparation of conventional and monoclonal antibodies, as well as for the design of synthetic vaccines.
Adjuvants, Immunologic↗
Disialoganglioside GD3 on human melanoma serves as a relevant target antigen for monoclonal antibody-mediated tumor cytolysis.
Monoclonal antibody MB3.6 (IgG3) recognizes disialoganglioside GD3, which represents a major surface marker on most human melanoma cells. We demonstrate that this antibody effectively lyses four human melanoma cell lines expressing significant levels of GD3 on their surface by either of two mechanisms: antibody-dependent cellular cytotoxicity (ADCC) or complement-mediated cytotoxicity. However, a melanoma cell line that expresses minimal levels of GD3 on 13% of the cells shows insignificant lysis by MB3.6 by either of these two mechanisms, suggesting that a threshold level of antigen expression may be required for effective in vitro cytolysis. In addition, monoclonal antibody (MAb) MB3.6 effectively inhibits establishment and growth of human melanoma tumors in the nude mouse when injected 24 hr after subcutaneous inoculation of tumor cells. Furthermore, MB3.6 produces specific regression of established melanoma tumors when injected 7 days after the subcutaneous inoculation of tumor cells. In contrast, tumor growth in animals injected with the melanoma cell line expressing minimal levels of GD3 was not affected by MAb MB3.6. These data indicate that once appropriate levels of the GD3 ganglioside are expressed on human melanoma cells, MAb MB3.6 can mediate tumor cell killing in vitro and in vivo and, thus, may prove useful for effective immunotherapy of human malignant melanoma.
Animals↗
Survival of bacteria and fungi in relation to water activity and the solvent properties of water in biopolymer gels.
Survival of bacteria (Rhizobium, Agrobacterium, and Arthrobacter spp.), fungal spores (Penicillium sp.), and yeasts (Saccharomyces sp.) was studied in relation to water activity (a(w)) and the presence of nutritive solutes. The cells were entrapped in polysaccharide gels, as is done to immobilize cells or enzymes, and then dehydrated. The number of living cells (10 g of dry polymer) remained constant for periods of storage of >3 years at 28 degrees C when the inocula were kept at an a(w) of <0.069. At a(w) values between 0.069 and 0.83 the number of survivors diminished more and more rapidly as the a(w) was raised. For a given a(w) and organism, there were large differences in survival rate as a function of the nutritive solutes used to culture the microorganisms. Low-molecular-weight compounds (with three or five carbon atoms) had a deleterious effect on survival, whereas compounds of higher molecular weight (C(6) to C(12)) had a protecting effect. Thus, the a(w) alone was not a sufficient explanation for the deterioration of the inocula. Survival seemed to be more directly related to some properties of the water in the biopolymer. New concepts such as the discontinuity of properties of water and the point of mobilization of solutes, already proposed by Duckworth and Kelly (J. Food Technol. 8:105-113, 1973) and Seow (J. Sci. Food Agric., 26:535-536, 1975), have been taken into consideration to explain the interactions of water with the biopolymer and their specific effects on the microorganisms.
Journal Article↗
Metabolic products from microorganisms. 230. Amiclenomycin-peptides, new antimetabolites of biotin. Taxonomy, fermentation and biological properties.
Four new and two known peptide antibiotics containing amiclenomycin (Acm) have been isolated from a culture of Streptomyces venezuelae Tü 2460: L-MeIle-L-Acm (1), L-Ile-L-Acm (2), L-MeVal-L-Acm (3), L-MeIle-L-Acm-L-Gln (4), L-Ile-L-Acm-L-Gln (5) and L-Val-L-Acm-L-Gln (6). These di- and tripeptides exhibited antimicrobial activity on a minimal medium against Gram-negative bacteria, which could be reversed by biotin. It was shown that the antibiotics were decomposed by peptidases to provide amiclenomycin (7) after their uptake into cells of Escherichia coli via peptide-permeases. The antimicrobial activity of the amiclenomycin-peptides was the inhibition of DAPA-aminotransferase by the amiclenomycin-warhead, however, amiclenomycin itself was hardly transported into the cells. Since the amiclenomycin peptides misuse general transport systems, they are presented here as examples for the illicit transport concept.
Aminobutyrates↗
Synthetic lipopeptide analogs of bacterial lipoprotein are potent polyclonal activators for murine B lymphocytes.
The lipoprotein from the outer membrane of Escherichia coli and other Enterobacteriaceae is a potent polyclonal activator for B lymphocytes. To determine the molecular structure responsible for the biologic activity of lipoprotein, a well-defined series of analogs of its N-terminal part was synthesized: S-(2,3-bis(palmitoyloxy)-(2-RS)-propyl)-N-palmitoyl-(R)-cysteine, -cysteine methyl ester, -cysteinyl-serine, -cysteinyl-seryl-serine, -cysteinyl-seryl-seryl-asparagine, and -cysteinyl-seryl-seryl-asparaginyl-alanine. All compounds were tested for mitogenic activity toward spleen cells from BALB/c, LPS-non-responder C3H/HeJ, and congenitally athymic C3H/Tif/Bom/nu/nu mice, measuring the incorporation of [3H]thymidine into DNA. Lymphocyte activation was confirmed by determination of the incorporation of [3H]uridine into RNA and [3H]leucine into protein. The synthetic lipopeptides were also investigated for their ability to stimulate B lymphocytes into immunoglobulin secretion, as shown by a hemolytic plaque assay. Throughout our studies, the compounds carrying two to five amino acids exhibited strong stimulation activity toward B lymphocytes comparable to native lipoprotein. In contrast, products containing only one amino acid, cysteine or cysteine methyl ester, were only marginally active, indicating that to obtain full biologic activity the presence of the hydrophilic dipeptide structure is necessary. All compounds exhibited only a marginal effect on thymocytes. Thus, a series of defined synthetic fragments of a bacterial outer membrane component exhibits a pronounced mitogenic and polyclonally stimulating activity towards B lymphocytes. The substances will be valuable tools for more detailed investigations on the molecular mechanisms of B cell activation.
Animals↗
[Basic principles of infant nutrition].
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Breast Feeding↗
[Platelet volume in myeloid splenomegaly].
A comparative study of the heterogeneity of the platelets volumes has been carried out in 9 patients with primary myeloid splenomegaly on their admission to hospital and during the evolution of their disease and in 40 healthy controls. The measurements were performed using a Coulter S-Plus system and different indexes have been calculated to better define the distribution of platelet volume. Platelet size distribution measurements demonstrated a double peculiarity in myeloid splenomegaly: an excessive microcytosis associated with a semi-linear and non log-normal distribution of macrothrombocyte volume. These data may be used as a good marker for the diagnosis of primary myeloid splenomegaly.
Aged↗
The mitogenic principle of Escherichia coli lipoprotein: B-lymphocyte mitogenicity of the synthetic analogue palmitoyl-tetrapeptide (Pam-Ser-Ser-Asn-Ala).
N-Palmitoyl-(S)-seryl-(S)-seryl-(S)-asparaginyl-(S)-alanine (Palmitoyl-tetrapeptide) is an analogue of the N-terminal part of the lipoprotein from the outer membrane of Escherichia coli. It was prepared by chemical synthesis and tested for biological activity in in vitro lymphocyte culture systems. In spleen cells of the inbred mouse strains C3H/HeJ, C3H/He/Bom/ nunu , and Balb/c, the compound exhibited stimulatory activity towards B-lymphocytes comparable to the effect of native lipoprotein, as measured by the incorporation of 3H-thymidine and 3H-uridine, and by a hemolytic plaque assay. The B-lymphocyte tumor cell line BCL1 was also activated by the compound. The results demonstrate, that the N-terminal tetrapeptide moiety of lipoprotein, linked to a lipophilic molecule, constitutes by itself a novel B-lymphocyte mitogen.
Animals↗
[Detection of rotavirus in patients with malabsorption].
Investigations were carried out to evaluate frequency and pathogenic effects of rotaviruses. For this purpose 53 biopsy specimens were taken from the jejunum, especially of children at an age up to 15. Because of their malabsorption the patients have undergone a special gastroenterological treatment for years or they only recently began with it, being suspected of suffering from this disease. Rotavirus antigen was indicated in 43% of the cases by means of immunohistology, at which only less part of the patients (sucklings and infants) showed a corresponding symptomatology. The greater part of the patients was without findings in the relevant sense.
Antigens, Viral↗
Mechanism of concanavalin A-induced anchorage of the major cell surface glycoproteins to the submembrane cytoskeleton in 13762 ascites mammary adenocarcinoma cells.
Concanavalin A (Con A)-induced anchorage of the major cell surface sialoglycoprotein component complex (ASGP-1/ASGP-2) was studied in 13762 rat mammary adenocarcinoma sublines with mobile (MAT-B1 subline) and immobile (MAT-C1 subline) cell surface Con A receptors. Treatment of cells, isolated microvilli, or microvillar membranes with Con A resulted in marked retention of ASGP-1 and ASGP-2, a Con A-binding protein, in cytoskeletal residues of both sublines obtained by extraction with Triton X-100 in PBS. When Con A-treated microvillar membranes were extracted with a buffer containing Triton X-100, the sialoglycoprotein complex was found associated in the residues with a transmembrane complex composed of actin, a 58,000-dalton polypeptide, and a cytoskeleton-associated glycoprotein (CAG), also a Con A-binding protein, in MAT-C1 membranes, and of actin and CAG in MAT-B1 membranes. Untreated membrane Triton residues retained very little ASGP-1/ASGP-2 complex. Association of the sialoglycomembrane complex and the transmembrane complex was also demonstrated in Con A-treated, but not untreated, microvilli by their comigration on CsCl gradients. Association of both complexes with the cytoskeleton of microvilli was shown by sucrose density gradient centrifugation. A fraction of the polymerized actin comigrated with the transmembrane complex alone in the absence of Con A and with both the transmembrane complex and the sialoglycoprotein complex in the presence of Con A. From these results we propose that anchorage of the sialoglycoprotein complex to the cytoskeleton on Con A treatment occurs by cross-linking ASGP-2, the major cell surface Con A-binding component, to CAG of the transmembrane complex, which is natively linked to the cytoskeleton via its actin component. Since Con A-induced anchorage occurs in sublines with mobile and immobile receptors, the anchorage process cannot be responsible for the differences in receptor mobility between the sublines.
Actins↗