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Biomedical subjects

E Winter

Publications and source records attributed to E Winter.

At least 73 records · Page 4Linked to original sources
PubMed1991

Tyrosine phosphorylation of a yeast 40 kDa protein occurs in response to mating pheromone.

Tyrosine phosphorylation of proteins in the yeast Saccharomyces cerevisiae has been examined following exposure to the mating pheromone alpha-factor. When a cells are treated with alpha-factor a protein of approximately 40 kDa molecular weight is tyrosine phosphorylated. This tyrosine phosphorylation response requires an intact signal transduction pathway, is not restricted to a short interval of the cell division cycle, and requires protein synthesis for its maximal accumulation. Mating competent fus3 deletion strains fail to elaborate the phosphotyrosine response. The possibility that FUS3 encodes the 40 kDa protein is discussed.

Blotting, Western↗
PubMed1991

Effects of an extract of Ginkgo biloba on learning and memory in mice.

The effects of an extract of Ginkgo biloba (EGb 761) on acquisition, performance, and retention of mice in an appetitive operant conditioning were investigated. The animals were trained for 30 consecutive days to acquire a two-lever response sequence followed by food reward. EGb 761 was administered daily at a dose level of 100 mg/kg PO. Drug treatment started four and eight weeks before the training and was maintained until a retention test 10 weeks after it. The results indicated that EGb 761 facilitated memory processes. EGb 761 quickened the acquisition and improved the performance of the two-response sequence: The number of correct responses was increased and correct responses were performed more frequently in the most effective manner. Besides, incorrect responses were reduced sooner and faster and to a lower level in EGb 761-treated mice. With regard to the retention EGb 761 improved the retrieval of the learned response.

Animals↗
PubMed1989

A DNA binding protein that recognizes oligo(dA).oligo(dT) tracts.

Oligo(dA).oligo(dT) tracts are common intergenic sequences in many organisms. In the yeast Saccharomyces cerevisiae, these sequences have been shown to influence transcription of adjacent genes. We have purified an oligo(dA).oligo(dT)-binding protein from S. cerevisiae and cloned its gene. This protein, which has been named datin, requires at least 9-11 bp of oligo(dA).oligo(dT) DNA for high affinity binding. The gene for datin (the DAT gene) encodes a 248-residue protein which contains a number of repeated sequence motifs. Datin purified from yeast corresponds to the N-terminal half of the DAT gene product. Null mutants in the DAT gene are viable but phenotypically distinguishable from congenic wild-type strains. We discuss unusual structural features and biochemical properties of datin in relation to its possible functions.

Amino Acid Sequence↗
PubMed1987

Directed Ig class switch recombination in activated murine B cells.

Immunoglobulin class switch recombination occurs at frequencies of up to 10%/cell/generation in activated murine B-lymphocytes. We analysed cH gene rearrangements and switch recombinations from active and inactive IgH loci of B-cells activated in various ways and immortalized by cell fusion. Although about half of the IgM+ cells show rearrangement of c mu genes, the deletion of c mu is a rare event. Half of the IgG3+ and IgG1+ cells show rearrangement of c mu genes on the inactive IgH locus and the other half of the IgG+ cells have deleted c mu from both IgH loci by switch recombination. This recombination is directed to the same switch regions on both IgH loci in 60-80% of all cases. Interleukin 4 may play a critical role in programming murine B-lymphocytes for specific switch recombination.

Amino Acid Sequence↗
PubMed1986

Oncogene amplification during tumorigenesis of established rat fibroblasts reversibly transformed by activated human ras oncogenes.

Normal rat fibroblasts of the established cell line Rat 4 were cotransformed with activated human ras oncogenes and with a cloned chicken thymidine kinase (tk) gene. Linkage between tk and ras genes allowed the isolation of oncogene deletion revertants and of cell clones showing varying degrees of malignant phenotype. Southern and Northern experiments in concert with tumorigenicity assays show that the malignant transformation of these cells by mutant ras oncogenes is a gradual but reversible process that depends on the relative abundance of oncogene sequences and their corresponding transcripts. We also show that moderate amplification of a c-K-ras oncogene in these cells results in a clear increase in their tumorigenicity and that the mutant gene present in low copy numbers in cultured cells undergoes amplification in the corresponding in vivo induced tumors.

Animals↗
PubMed1985

VH-gene expression in murine lipopolysaccharide blasts distributes over the nine known VH-gene groups and may be random.

VH-gene expression in hybridomas derived from lipopolysaccharide-activated B cells was analyzed. Isolated cytoplasmic RNA was hybridized to probes representing the 9 known VH-gene groups or subjected to mRNA sequencing. In the collection of hybridomas VH genes of all 9 groups are expressed at frequencies which in most correlate reasonably well with the relative complexities of the groups. In 51 out of 54 RNA samples VH-gene transcripts could be identified and corresponded to one of the known VH-gene groups. It therefore appears that the latter essentially represent the VH-gene cluster of the mouse.

Animals↗
PubMed1985

Members of novel VH gene families are found in VDJ regions of polyclonally activated B-lymphocytes.

Four potentially productive and two non-productive VDJ gene segments were isolated from the DNA of mouse B-lymphocytes which had been polyclonally activated by bacterial lipopolysaccharide (LPS). Three VDJ regions exhibit VH genes which stem from two novel VH gene families. The complexity of these families is 5-9 genes. One of the non-productive VDJ regions exhibits a D segment which may have been generated by joining of two DSP2 segments. Both non-productive VDJ regions appear to contain rearranged pseudo VH genes. Three potential somatic mutations distributed over two productive VDJ regions are observed.

Animals↗
PubMed1985

A method to detect and characterize point mutations in transcribed genes: amplification and overexpression of the mutant c-Ki-ras allele in human tumor cells.

A significant percentage of human tumors contain activated ras oncogenes that have acquired oncogenic potential as a result of somatic point mutations at codon 12 or 61 of the encoded ras gene product. We report here a method to detect and characterize mutations in ras genes that is based on the ability of pancreatic ribonuclease (RNase A; EC 3.1.27.5) to cleave RNA heteroduplexes containing single-base mismatches. Using this method, we show that certain human tumor cells contain mutant c-Ki-ras genes, and we define the nature and position of these mutations. At the same time, we describe the presence and estimate the expression of both normal and mutant c-Ki-ras alleles in the same tumor cells. This method should be useful for the diagnostic detection and characterization of single point mutations in expressed genes.

Alleles↗
PubMed1985

Changes in the H-1 histone complement during myogenesis. I. Establishment by differential coupling of H-1 species synthesis to DNA replication.

Proportions of the four major chicken H-1 histones (referred to as H-1's a-d) change during in vitro skeletal myogenesis. As myoblasts fuse and differentiate into myotubes, the relative amount of H-1c increases dramatically. The change occurs primarily because synthesis of the H-1 species is coupled to DNA synthesis to different extents. H-1c synthesis is least tightly coupled to DNA replication in precursor myoblasts and in differentiated myotubes. Thus H-1c synthesis predominates after dividing myoblasts fuse into postmitotic myotubes. This results in the replacement of pre-existing H-1 and therefore increases the relative amount of H-1c. Differences in the stability of the H-1's are also involved in changing H-1 proportions. The results show that changes in H-1 proportions during myogenesis are a consequence of withdrawal from the cell cycle. The data provides a general mechanistic explanation of how tissue-specific H-1 proportions are established.

Animals↗
PubMed1985

Changes in the H-1 histone complement during myogenesis. II. Regulation by differential coupling of H-1 variant mRNA accumulation to DNA replication.

We have shown that changes in proportions of the four chicken H-1's during in vitro myogenesis are primarily the result of differential coupling of their synthesis to DNA replication (see the previous paper). We show here that the four major chicken H-1's are encoded by distinct mRNAs which specify primary amino acid sequence variants. Accumulation of the H-1-variant mRNAs is coupled to DNA replication to different extents. The level of mRNA encoding H-1c (the H-1 variant that increases relative to the other H-1's in nondividing muscle cells) is completely uncoupled. In contrast, the level of mRNAs encoding H-1's a, b, and d (which have levels that decrease in nondividing muscle cells) are more tightly coupled. Polyadenylation is not involved in uncoupling H-1c mRNA accumulation from DNA replication.

Amino Acid Sequence↗
PubMed1983

Effects of synthesis inhibition and nervous activity on concentrations of neuronal substance P.

1. When dorsal root ganglia were incubated in vitro with a range of concentrations of anisomycin, incorporation of [ 3H ]lysine into protein and synthesis of substance P(SP) were inhibited to a similar extent confirming that SP is synthesised by a conventional ribosomal mechanism. 2. Doses of anisomycin sufficient to inhibit protein synthesis in mouse CNS in vivo by greater than 95% did not cause a significant fall in the SP content of any of five brain areas, spinal cord, dorsal root ganglia or cornea over an 8 h period. 3. Electrical stimulation of the hind limbs however, produced a 25% fall in the SP content of the dorsal spinal cord of these animals. 4. These findings suggest that the turnover-time of neuronal SP is much longer than that of non-peptide neurotransmitters.

Animals↗
PubMed1982

Biosynthesis, axonal transport and turnover of neuronal substance P.

In dorsal root ganglia substance P is synthesized ribosomally, probably via a precursor. A second peptide, apparently a modified form of substance P (8-11), is cosynthesized with substance P and transported with it down both dorsal roots and peripheral branches. Four times as much substance P-like immunoreactivity is transported peripherally as centrally. Only 30% of axonal substance P-like immunoreactivity is available for rapid axonal transport and this is transported at a rate of 4.9 mm h-1. Axonal transport is not necessary for substance P synthesis. Doses of anisomycin which inhibit CNS protein synthesis by more than 95% do not cause any fall in substance P levels over an eight-hour period in ganglia, spinal cord or brain, suggesting that turnover is slower than that of conventional transmitters. However, stimulation of the hindlimbs of these animals reduces substance P levels in the dorsal horn. The turnover rate of spinal cord substance P, estimated either by relating the amount transported down dorsal roots to that in terminals or by measuring the decline of substance P levels after intrathecal colchicine, is four to five days. The functional organization of the substance P neuron is discussed with particular reference to the maintenance of peptide levels in terminals.

Amino Acids↗
PubMed1979

[Treatment of acute schizophrenic stupor: the effect of biperiden (author's transl)].

The study reports about the intravenous application of Biperiden at patients with acute hypokinetic reaction suffering from schizophrenia of the paranoid-hallucinatory type. In all of the six cases examined a fast abolition of the stupor could be observed. The pathophysiological mechanisms deriving from our clinical experiences are discussed. Furthermore, a therapeutic procedure is suggested to treat acute schizophrenic stupor merely with drugs.

Acute Disease↗