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T Vogel

Publications and source records attributed to T Vogel.

At least 109 records · Page 6Linked to original sources
PubMed1990

Site-directed mutations of human growth hormone that selectively modify its lactogenic activity and binding properties.

Two novel analogs of human (h) GH, 1) Des-7-hGH (Arg8Met, Asp11Ala) in which the Arg8 was substituted by Met and Asp11 by Ala, and 2) bovine (b) GH/hGH hybrid II (MetAla 1-13/14-191, Ala11Asp) composed of 13 N-terminal amino acid of bGH and elongated by two amino acids (Met-Ala-1-13) and 14-191 amino acids of hGH, were constructed and expressed in Escherichia coli. CD spectra indicated that the alpha-helix content of the purified proteins was similar to that of the native hormone. Both analogs retained their full ability to stimulate the proliferation of Nb2 lymphoma cells, and their binding to the lactogen receptors in homogenate of Nb2 cells and in microsomal fraction from bovine lactating mammary gland was only slightly reduced. However, their ability to bind to the somatogen receptors in intact IM-9 lymphocytes and bovine liver was reduced by 7- to 11-fold (bGH/hGH hybrid II) and 20- to 30-fold (Des-7-hGH). Both analogs were able to down-regulate the respective lactogen and somatogen receptors in intact Nb2 and IM-9 cells. The galactopoietic activity of both analogs in the lactating bovine mammary explants bioassay was almost completely abolished, and the bGH/hGH hybrid II exhibited a remarkable antagonistic activity. These results further indicate that the lactogen receptors in different species or organs are not identical. We have shown that the new recombinant analogs of hGH that recognize both somatogen and lactogen receptors but have modified postreceptor effects are helpful in elucidating these differences.

Base Sequence↗
PubMed1989

Intravenous infusion of apolipoprotein E accelerates clearance of plasma lipoproteins in rabbits.

Plasma cholesterol levels in cholesterol-fed rabbits were markedly reduced by the intravenous infusion or bolus injection of recombinant human apo E or rabbit plasma apo E. Administration of 6-70 mg of apo E resulted in an approximately 20-40% acute reduction in plasma cholesterol levels within 2-3 h. Plasma cholesterol levels remained reduced for 4-8 h after the administration of apo E. Furthermore, the intravenous injection of apo E reduced the plasma cholesterol levels in Watanabe heritable hyperlipidemic rabbits. The addition of apo E to [14C]cholesterol-labeled canine thoracic duct lymph or [14C]cholesterol-labeled chylomicrons resulted in accelerated plasma clearance of these diet-induced lipoproteins in normal rabbits, with the uptake occurring primarily in the liver. This study suggests that the amount or availability of apo E in the plasma of cholesterol-fed rabbits may be rate limiting for the normal clearance of diet-induced remnant lipoproteins.

Animals↗
PubMed1989

The antigenic epitopes of human grown hormone as mapped by monoclonal antibodies.

The antigenic epitopes of human GH (hGH) have been investigated using monoclonal antibodies (Mabs) to hGH. A panel of 12 Mabs was incorporated into two-site binding assays in order to investigate the antigenic surface of hGH. Nine reaction patterns were observed. The Mabs were further characterized in terms of their cross-reactivity with human placental lactogen, human PRL, with recombinant hGH molecules (MetLeu8hGH, Met14hGH), and with fragments derived from enzymatic or chemical digestion of hGH. These studies provided information on the antigenic sites that are shared with human placental lactogen and on the N-terminal and C-terminal regions of the hGH molecule. Based upon these findings, we tentatively suggest the epitope model for hGH comprising at least 10 antigenic sites (epitopes) which may be grouped into five antigenic regions.

Animals↗
PubMed1989

Chimeric bovine-human growth hormone prepared by recombinant DNA technology: binding properties and biological activity.

A chimeric bovine GH (amino acids Met-Asp-Gln-greater than 1-23) and human GH (hGH) (amino acids 24-191) plasmid was constructed and expressed in Escherichia coli. The purified protein (chimeric GH) exhibited a 2-3 order of magnitude lower affinity toward lactogenic receptors in Nb2 lymphoma cells, microsomal fractions from bovine mammary gland and male rat liver. The affinity towards somatogenic receptors in IM-9 human lymphocytes and male rat liver was decreased to a much lesser degree. This diminished affinity towards lactogenic receptors was accompanied by a parallel decrease in the ability of the chimeric GH to stimulate proliferation of Nb2-11C lymphoma cells and the lipogenesis in bovine mammary gland. This implies that occupation of the respective receptors by either chimeric GH or hGH leads to identical postreceptoral effects. The chimeric GH was also capable of down-regulating the lactogenic receptors in Nb2 lymphoma cells and was recognized by three anti-hGH monoclonal antibodies. These and previously published results indicate that the N-terminal part of hGH is essential for the high affinity binding to lactogenic receptors and subsequent biological effect. Removal or replacement by a corresponding part of bovine GH converts the hormone, respectively to weak antagonist or agonists. Analysis of our data, based on hydropathy index leads us to suggest that the high affinity binding site of the hGH towards lactogenic receptors is mainly confined to amino acids nos. 8-18.

Animals↗
PubMed1987

Comparative study of in vitro and in vivo modulation of lactogenic and somatotropic receptors by native human growth hormone and its modified analog prepared by recombinant deoxyribonucleic acid technology.

A modified analog of human GH (hGH), prepared by recombinant DNA technology, that lacks 13 amino acids at the amino terminus (Met14hGH), was able to compete with [125I]hGH for binding to lactogenic receptors in Nb2-11C rat lymphoma cells, to somatotropic receptors in IM-9 human lymphocytes, and to both lactogenic and somatotropic receptors in the microsomal fraction of virgin female rat liver. Exposure of intact Nb2 or IM-9 cells to Met14hGH did not reduce the number of surface or intracellular receptors, as compared to the control without hormone. A parallel exposure to 500-fold lower concentrations of hGH resulted in 77-93% reduction in both surface and intracellular receptors. In contrast to [125I]hGH, [125I]Met14hGH was not taken up by the intact Nb2 lymphoma cells. Infusion of anesthetized female virgin rats for 3 h with hGH down-regulated both lactogenic and somatotropic receptors in the liver. A similar infusion with up to 200-fold higher amounts of Met14hGH did not lower the number of total receptors, indicating lack of down-regulation. Some decrease in the binding to free receptors was observed, suggesting that Met14hGH is capable of binding to liver receptors in vivo.

Animals↗
PubMed1986

Inhibition of lactogenic activities of ovine prolactin and human growth hormone (hGH) by a novel form of a modified recombinant hGH.

A recombinant analog of human GH (hGH) lacking 13 amino acids at the amino-terminus (Met14hGH) inhibited the hGH- or ovine PRL (oPRL)-stimulated proliferation of Nb2 lymphoma cells and bovine PRL-stimulated fat synthesis and alpha-lactalbumin secretion in explants from bovine lactating mammary gland. The inhibition was competitive in nature, and in Nb2 cells could be abolished by an excess of hGH or oPRL. Inhibition of oPRL-stimulated proliferation of Nb2 cells by Met14hGH could also be specifically abolished by anti-hGH monoclonal antibodies. Met14hGH had no growth-stimulating activity in Nb2 cells and was not cytotoxic. It also did not affect glucose uptake by the mammary gland explants. Met14hGH competed with [125I]hGH for binding to intact Nb2 cells, IM-9 lymphocytes, solubilized microsomal fraction from lactating bovine mammary gland, and microsomal fraction from the liver of female virgin rats, but its affinity for those receptors was 2 orders of magnitude lower than the affinity of hGH. Since Met14hGH used in most experiments contained about 25% impurities and degradation products, a small amount of it was further purified by immunoaffinity chromatography. Two purified fractions, one consisting of a single 20K protein and the other accompanied by a small amount of 25K protein, were obtained. Both fractions exhibited increased inhibition of hGH- or oPRL-stimulated proliferation of Nb2 cells, thus indicating that the inhibitory activity results from the intact Met14hGH molecule. To the best of our knowledge, this is the first report describing the inhibition of lactogenic hormone activities by a modified hGH.

Animals↗
PubMed1985

Human apolipoprotein E expression in Escherichia coli: structural and functional identity of the bacterially produced protein with plasma apolipoprotein E.

Human apolipoprotein E (apoE) was produced in Escherichia coli by transforming cells with an expression vector containing a reconstructed apoE cDNA, a lambda PL promoter regulated by the thermolabile cI repressor, and a ribosomal binding site derived from the lambda cII or the E. coli beta-lactamase gene. Transformed cells induced at 42 degrees C for short periods of time (less than 20 min) produced apoE, which accumulated in the cells at levels of approximately equal to 1% of the total soluble cellular protein. Longer induction periods resulted in cell lysis and the proteolytic destruction of apoE. The bacterially produced apoE was purified by heparin-Sepharose affinity chromatography, Sephacryl S-300 gel filtration, and preparative Immobiline isoelectric focusing. The final yield was approximately equal to 20% of the initial apoE present in the cells. Except for an additional methionine at the amino terminus, the bacterially produced apoE was indistinguishable from authentic human plasma apoE as determined by NaDodSO4 and isoelectric focusing gel electrophoresis, amino acid composition of the total protein as well as its cyanogen bromide fragments, and partial amino acid sequence analysis (residues 1-17 and 109-164). Both the bacterially produced and authentic plasma apoE bound similarly to apolipoprotein B,E(low density lipoprotein) receptors of human fibroblasts and to hepatic apoE receptors. Intravenous injection resulted in similar rates of clearance for both the bacterially produced and authentic apoE from rabbit and rat plasma (approximately equal to 50% removed in 20 min). The ability to synthesize a bacterially produced human apolipoprotein with biological properties indistinguishable from those of the native protein will allow the production of large quantities of apoE for use in further investigations of the biological and physiological properties of this apolipoprotein.

Amino Acid Sequence↗
PubMed1979

Altered restriction endonuclease cleavage pattern of simian virus 40 DNA.

Three different groups of temperature-sensitive mutants of simian virus 40, isolated and characterized by Chou and Martin (J. Virol. 13:1101--1109, 1974), have been analyzed by using restriction endonucleases. Differences between the restriction endonuclease cleavage pattern of these mutants and that of the standard simian virus 40 strain have been mapped. These include the following observations: (i) tsD202 carries a defective HaeIII cleavage site at position 0.9 map units; (ii) tsB204 exhibits a defective HaIII site at position 0.21 and a defective HinIII site at 0.655 map units, and (iii) tsC219 carries a new HinIII site at position 0.15. We have isolated a few wild-type revertants from each of the temperature-sensitive mutant strains; each displays the endonuclease cleavage pattern of its parental temperature-sensitive strain.

DNA Restriction Enzymes↗
PubMed1977

Recombination between endogenous and exogenous simian virus 40 genes. II. Biochemical evidence for genetic exchange.

The genome of the simian virus 40 (SV40) temperature-sensitive (ts) mutant tsD202 rescued by passage on transformed permissive monkey lines (see accompanying paper [Y. Gluzman et al., J. Virol. 24:534-540, 1977]) was analyzed by restriction endonuclease cleavage mapping to obtain biochemical evidence that the rescue of the ts phenotype results from recombination with the resident SV40 genome of the transformed cell. It was demonstrated that the endonuclease R. HaeIII cleavage site, which is located at 0.9 map unit in the standard viral genome (and which is in the proximity of the known map position of the tsD lesion), is missing in the DNAs of the parental tsD202 virus and of three independent revertants of tsD202. In contrast, this cleavage site was shown to be present in the DNAs of four out of five independently derived rescued D202 populations and in the DNA of the SV40 strain, 777, used to transform the monkey cells. Comparison of the endonuclease R. Hin(II + III) cleavage patterns of SV40 strain 777 DNA and tsD202 DNA revealed differences in the electrophoretic mobilities of Hin fragments A, B, and F. However, the corresponding Hin fragments from all four rescued D202 genomes were identical in their mobilities to those of tsD202 DNA, indicating that these regions of the rescued D202 genome are characteristic of the tsD202 parent. We conclude, therefore, that the genome of the rescued D202 virus is a true recombinant, since it contains restriction endonuclease cleavage sites characteristic of both parents, the endogenous resident SV40 genome of the transformed monkey cells and the exogenous tsD202 mutant.

Cell Line↗
PubMed1976

H5 Histone and DNA-relaxing enzyme of chicken erythrocytes. Interaction with superhelical DNA.

The interaction of closed circular duplex DNA with the lysine-rich H5 histone fraction of avian erythrocytes has been studied. H5, like H1 histone, interacts preferentially with superhelical DNA. The extent of interaction increases with increasing negative or positive superhelicity. Salt-extracted lysine-rich histones show the same specificity for interaction with superhelices as do acid-extracted preparations. Chicken erythrocyte nuclei contain DNA-relaxing enzyme. This enzyme is extracted from the nuclei at lower salt concentrations than those required to extract H1 and H5 histones and is, therefore, probably a function of a protein distinct from H1 and H5 histones.

Animals↗
PubMed1976

The effect of superhelicity on the interaction of histone f1 with closed circular duplex DNA.

A set of covalently closed circular duplex simian virus 40 DNA preparations of varying superhelical densities was prepared by closure of nicked duplex DNA with polynucleotide ligase in the presence of varying amounts of ethidium. The resulting molecules were tested for complex formation with the lysine-rich histone f1. The results confirmed earlier experiments in demonstrating that f1 histone reacts preferentially with superhelical DNA compared to relaxed circular DNA. Furthermore, the extent of the reaction is demonstrated to depend on the superhelical density. At the relatively low ratios of histone to DNA used in these experiments, the product of the interaction of f1 histone with superhelical DNA does not precipitate. At higher ratios of histone to DNA, an insoluble aggregate is formed.

DNA, Circular↗
PubMed1975

The interaction of histones with simian virus 40 supercoiled circular deoxyribonucleic acid in vitro.

The interaction of supercoiled, circular SV40 DNA with calf thymus histone fractions has been studied. Five- to ten-fold less f1 histone is required to complex a given amount of DNA compared to the other histones. When the supercoiled DNA is converted to either the relaxed circular form, or full length linear molecules, or gragmented linear or denatured stands, the efficiency of complex formation with f1 histone markedly decreases. We conclude that f1 histone has a special ability to interact with supercoiled DNA. This conclusion is supported by the fact that supercoiled circular Col E1 DNA interacts with f1 as efficiently as does SV40 DNA.

Animals↗
PubMed1975

Interaction of f1 histone with superhelical DNA.

The superhelicity of double-stranded, closed circular SV40 DNA was altered by the addition of various amounts of ethidium bromide. The interaction of f1 histone with the series of molecules of various superhelicities was studied. The extent of interaction increases with increasing superhelicity regardless of whether it is of the positive or negative sense. The interaction of f1 histone with superhelical DNA is shown to be reversible.

Binding Sites↗
PubMed1975

Specific binding of the first enzyme for histidine biosynthesis to the DNA of histidine operon.

Studies were done to examine direct binding of the first enzyme of the histidine biosynthetic pathway (phosphoribosyltransferase) to 32P-labeled phi80dhis DNA and competition of this binding by unlabeled homologous DNA and by various preparations of unlabeled heterologous DNA, including that from a defective phi80 bacteriophage carrying the histidine operon with a deletion of part of its operator region. Our findings show that phosphoribosyltransferase binds specifically to site in or near the regulatory region of the histidine operon. The stability of the complex formed by interaction of the enzyme with the DNA was markedly decreased by the substrates of the enzyme and was slightly increased by the allosteric inhibitor, histidine. These findings are consistent with previous data that indicate that phosphoribosyltransferase plays a role in regulating expression of the histidine operon.

ATP Phosphoribosyltransferase↗
PubMed1975

[Pathogenetic model-theories of endogenous psychoses (author's transl)].

The multiplicity of frequently conflicting views in the psychiatry of today inspires the wish for a uniform way thinking about the thorough knowledge and the many hypotheses that have become almost boundlessly vast. Such ideas of models as have played a part for quite some time in the mathematical and natural sciences, and of late in the sociology, are also to be found in the field of psychiatry, without however always being called so expressis verbis. Guided by the historical development an attempt has been made to expose model-like ideas about the etiology and pathogenesis of endogenic psychoses, first of all of schizophrenia, as they have become decisive for modern psychiatry. It appears that in the abbreviation of the "model" the basis for a discussion already overdue is to be found.

Anthropology↗