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Biomedical subjects

H Knüfermann

Publications and source records attributed to H Knüfermann.

10 recordsLinked to original sources
PubMed1978

[Progress in the therapy of medulloblastoma].

The nearly exclusive metastatic spread of the radiosensitive medulloblastoma into the fluid spaces of the liquor system allows a curative therapeutic attempt by a systemic radiation. The actual 5-years survival rate is about 40%. It should be possible to improve it to up to 50% by consequently applicating radiotherapy. A prospective study concerning the possibilities of chemotherapy presently underway, does not yet permit a definite statement. The most essential complication after radiotherapy of children concerns the symmetric reduction of growth.

Brain Neoplasms↗
PubMed1977

Abnormality of erythrocyte membrane protein in a case of congenital stomatocytosis.

A new method of membrane protein analysis was used to demonstrate an erythrocyte membrane protein anomaly. Our approach employed electrofocusing linked to sodiumdodecylsulfate polyacrylamide gel electrophoresis. We observed an aberrant protein, isoelectric at approximately pH 4.5 with an apparent molecular weight of approximately 25,000 in membrane preparations from a patient with congenital stomatocytosis. This protein has not been observed in any healthy donor examined to date.

Anemia, Hemolytic, Congenital↗
PubMed1977

Characterization of macrophage cytotoxicity factor (MCF).

Allogenetically sensitized T lymphocytes secrete in the presence of the specific antigen a factor which renders macrophages cytotoxic to target cells in vitro, macrophage cytotoxicity factor. Cytotoxicity is expressed as 51Cr release from labeled target cells. Experiments are described to characterize chemically nonspecific MCF activity. After purification on a DEAE-cellulose column, active material elutes from Sephadex G-100 in a single peak. Assaying individual fractions of this peak shows that nonspecific MCF activity is found at a mol. wt. of 28,000+/-5,000. This material is stable at -70 degrees C several months.

Animals↗
PubMed1976

The major "intrinsic" membrane protein of human erythrocytes. Preparative isolation and immunoelectrophoretic analyses.

(1) Preparative dodecyl sulfate gel electrophoresis of human erythrocyte membrane proteins has been used to isolate dodecylsulfate band 3 containing the M,N-glycoprotein and the major "intrinsic" membrane protein (Fairbanks, G., Steck, T.L. and Wallach, D.F.H. (1971) Biochemistry 10, 2606-2617; Bretscher, M.S. (1971) J. Mol. Biol. 59,351-357; Bretscher, M.S. (1971) Nat. New Biol. 231, 229-232 and Marchesi, V.T. and Andrews, E.P. (1972) Science 174, 1247-1248). Subsequent isoelectric focusing in polyacrylamide gels containing Triton X-100 separates these two entities and allows their simultaneous purification. (2) The proteins thus obtained retain their antigenic properties. They are pure according to electrophoretic and immunoelectrophoretic criteria. However, crossed immunoelectrophoresis yields evidence for molecular microheterogeneity of the major "intrinsic" protein. (3) Analyses utilizing crossed immunoelectrophoresis with antibodies absorbed with intact erythrocytes show that the major "intrinsic" protein possesses antigenic determinants on both membrane surfaces and therefore spans the erythrocyte membrane. All determinants of the M,N-glycoprotein detectable with our antibodies were found solely on the exterior membrane surface. (4) Neither the major "intrinsic" membrane protein nor the major M,N-glycoprotein bound significantly to concanavalin A in crossed immunoaffinoelectrophoresis.

Amino Acids↗
PubMed1975

Quantitative immunoelectrophoresis of proteins in human erythrocyte membranes. Analysis of protein bands obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

1. We have defined conditions that permit quantitative immunoelectrophoresis in agarose gels of dodecyl sulfate-solubilized erythrocyte membrane proteins. 2. Using human serum albumin, transferrin, MN-glycoprotein (glycophorin) and crude spectrin as test proteins, we found that accurate analyses are possible if samples and gels are 1% in non-ionic detergent (Berol EMU-043) or Triton X-100) and if no more than 100 nmol free dodecyl sulfate is applied per sample. 3. Dodecyl sulfate treated membranes analyzed by crossed immunoelectrophoresis using rabbit antibodies against membrane material yielded optimal precipitation patterns in gels containing 1% of non-ionic detergent. 4. Crossed immunoelectrophoresis in the presence of 1% of Berol revealed precipitates when 10 protein bands defined and isolated by preparative dodecyl sulfate-polyacrylamide gel electrophoresis were run against anti-membrane antibodies. Seven of these bands showed more than one precipitation arc, indicating the presence of more than one antigenic component. 5. Crossed-line immunoelectrophoresis showed that dodecyl sulfate-polyacrylamide gel electrophoresis bands 1, 2 and 2.1 shared common antigenic components. The MN-glycoprotein was present in bands 3, 4A, 4B and 5, where antigenic components of the major intrinsic erythrocyte membrane protein, band 3, were also found. 6. After absorption of the anti-membrane antibody with intact erythrocytes, immunoelectrophoresis showed the disappearance of the MN-glycoprotein precipitates. An increase in the area below the precipitate corresponding to the major intrinsic protein (band 3) was also observed, indicating exposure of some antigens of this protein on the outer surface of intact cells. 7. After absorption of the antibody preparation with washed erythrocyte membranes, immunoprecipitates were not seen in any experiments, indicating that all antigenic determinants observed are exposed at one or both surfaces of the membrane. 8. Our analyses indicate that the peptide moieties of serum lipoproteins do not constitute a significant component of erythrocyte membranes.

Antibody Specificity↗
PubMed1975

Immunochemical analyses of membrane-bound complement. Detection of the terminal complement complex and its similarity to "intrinsic" erythrocyte membrane proteins.

(1) Membranes of sheep erythrocytes lysed with antibody and human or rabbit complement were solubilized in non-ionic detergents (Triton X-100 or Berol EMU-043) and analysed immunochemically using antisera directed against individual complement components. The precipitation behaviour of membrane-bound C3, C5, C6 and C9 components of complement was examined by immuno-double diffusion, rocket- and crossed immunoelectrophoresis performed in agarose gels containing 1% non-ionic detergent. (2) Membrane-bound C5, C6 and C9 are antigenically altered compared with the native (serum) components. (3) Immuno-double diffusion in the presence of non-ionic detergents reveals formation of C5-C6-C9 complexes on the membranes; these complexes are stable in non-ionic detergent. No complex formation was detected in serum between native C5, C6 and C9 components. There was also no evidence for complexing between membrane-bound C3, C4 or membrane proteins and the "late-reacting" complement components. (4) The extractability of complement components by various manipulations has been studied by use of quantitative rocket immunoelectrophoresis. Up to 65% of membrane-bound C3 is readily extracted by dialysis of membranes against 1mM EDTA, pH 8.0, 100 mM EDTA, pH 8.0, 1.2 NaCl plus or minus EDTA, by extraction in isotonic buffers at 37 degrees C, by heating at 45 degrees C over several hours, or by treating membranes with 1 mM p-chloromercuribenzoate sulfonate. In contrast, less than 6% of the terminal complement complex can be eluted by any of the described methods or combination of methods. (5) Our data suggest that the terminal complement complex associates with membrane "core" components through apolar interactions.

Animals↗
PubMed1975

Two-dimensional separation of erythrocyte membrane proteins.

1). Erythrocyte membrane proteins eluted with Triton X-100 or dilute EDTA have been separated two-dimensionally by isoelectric focusing in polyacrylamide gels containing 1 percent Triton X-100 plus 8 M urea, followed by electrophoresis using sodium dodecyl sulfate. Characteristic patterns, consistent among 40 healthy donors, were obtained. 2. The resulting patterns contain at least 30 components. The "spectrin" components (sodium dodecyl sulfate Bands 1 and 2) focus in the same pH range. Other membrane components giving single bands in sodium dodecyl sulfate electrophoresis appear to be heterogeneous. 3. Triton X-100, but not EDTA, extracts the principal membrane glycoproteins and the major "intrinsic" protein. Otherwise, proteins preferentially eluted by EDTA extract poorly with Triton X-100 and vice versa. 4. Membrane glycoproteins migrate anodally during electrofocusing and can be purified in a simple, one-step procedure.

Cell Membrane↗
PubMed1975

Rapid preparative isolation of major erythrocyte membrane proteins using polyacrylamide gel electrophoresis in sodium dodecylsulfate.

1. We describe a simple method for preparative, sodium dodecylsulfate/polyacrylamide gel electrophoresis of the major proteins in human erythrocyte membranes. 2. The method is based on extraction of prestained proteins from gel slabs. Three different fluorescent dyes (o-phthalaldehyde, fluorescamine and 1-dimethyl-aminonaphthalene-5-sulfonylchloride) have been used for pretaining. The method allows separation of up to 75 mg membrane protein and isolation of mg quantities of all major erythrocyte ghost proteins, while preserving the high resolution of analytical polyacrylamide gel electrophoresis. 3. Yield depends on extraction conditions and the molecular weight of the proteins being eluted. It ranges from 43-48% for protein 1 (apparent mol. wt approx. 310000) and 72-78% for protein 3(apparent mol. wt 87 000-93 000) to 87-93% for protein 6 (apparent mol. wt 35 000). 4. The labile behaviour of the high molecular "spectrin" bands (bands 1 and 2) is described. Extraction at room temperature tends to split these proteins into products of lower molecular weight. In contrast, the minor protein components 2.1 and 2.2 tend to aggregate yielding components 1 and 2. 5. N-terminal amino acid analyses have been performed on proteins 1, 2, 3, 4A, 4B, 5 and 6. Each of these bands contains several N-terminals, most of which appear constant. Some additional N-terminal amino acids vary from one donor to the next.

Amino Acid Sequence↗
PubMed1975

Escherichia coli capsule bacteriophages. IV. Free capsule depolymerase 29.

The free host capsule depolymerase, induced by Escherichia coli capsule bacteriophage no. 29, and causing the formation of haloes around its plaques, has been purified to homogeneity. As judged from the following facts, this "enzyme" consists of free phage 29 spikes. (i) Detached phage organelles and depolymerase 29 particles exhibit the same molecular weight (about 245,000, as determined from the sedimentation equilibrium), contain polypeptide chains of the same two sizes (57,000 plus or minus 3,000 and 29,500 plus or minus 2,000, as determined by SDS-PAA gel electrophoresis), and have (within experimental error) the same sedimentation coefficient, isoelectric point, and amino acid composition. (ii) Isolated depolymerase and phage spikes in situ both catalyze the hydrolysis of glucosidic bonds in host capsular polysaccharide, leading ultimately to the formation of oligosaccharide fragments of one, two, and three hexasaccharide repeating units. (iii) Depolymerase 29 and phage 29 spikes have roughly the same electron optical dimensions. As tentatively estimated from the total and the virus-associated capsule depolymerase activity in the lysates, phage 29 infection seems to produce eight to seventeen times more free than incorporated spikes.

Amino Acids↗