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Biomedical subjects

E Harms

Publications and source records attributed to E Harms.

At least 109 records · Page 6Linked to original sources
PubMed1982

Monensin inhibits Semliki Forest virus penetration into culture cells.

The carboxylic ionophores monensin and nigericin, at concentrations higher than 10 and 6 muM, respectively, prevent the penetration of the Semliki Forest virus (SFV) genome into the cytosol of baby hamster kidney (BHK-21) cells and thereby inhibit viral replication. In the absence of inhibitors, the entry of SFV is known to proceed by adsorptive endocytosis in coated vesicles, followed by acid-triggered membrane fusion in intracellular vacuoles or lysosomes. The results show that binding of the virus to the cell surface, adsorptive endocytosis, and intracellular transport of viruses to the lysosomes are only marginally affected by the ionophores. No direct virucidal effect is observed, nor is the membrane fusion activity of the virus at low pH directly affected. Sequential addition of monensin and ammonium chloride (a non-related lysosomotropic inhibitor of SFV entry) indicates that both inhibitors affect the same step in the entry pathway. On the basis of these data and the known effects of carboxylic ionophores and lysosomotropic weak bases on cellular pH gradients, we conclude that monensin inhibits penetration by increasing the pH in endocytic vacuoles and lysosomes above pH 6, which is the pH threshold for the viral membrane fusion activity.

Animals↗
PubMed1981

Inhibition of in vitro biosynthesis of N-acetylneuraminic acid by N-acyl- and N-alkyl-2-amino-2-deoxyhexoses.

The biosynthesis of N-acetylneuraminic acid is markedly inhibited by 2-deoxy-2-propionamido-D-glucose (GlcNProp) and to a much lesser extent by 2-deoxy-2-propionamido-D-mannose (ManNProp), but not by 2-deoxy-2-propionamido-D-galactose and N-methylated derivatives of 2-amino-2-deoxy-D-glucose. 2-Deoxy-2-trimethylamino-D-glucose is a weak inhibitor of 2-acetamido-2-deoxy-D-mannose metabolism. When incubated in a cell-free system from rat liver, GlcNProp gives the 6-phosphate, which is converted into N-propionylneuraminic acid. Evidence is presented which shows that it is the metabolites GlcNProp-6-P and ManNProp-6-P which are the competitive inhibitors, and not GlcNProp itself.

Animals↗
PubMed1981

Properties of N-acetyl-beta-D-hexosaminidase from isolated normal and I-cell lysosomes.

Using a combination of differential centrifugation and free flow electrophoresis (Harms, E., Kern, H., and Schneider, J. A. (1980) Proc. Natl. Acad. Sci. U. S. A. 77, 6139-6143) a single population of highly purified lysosomes was obtained from normal, I-cell disease type 1, and I-cell disease type 2 cultured fibroblasts. Our findings indicate that most of the residual acid hydrolase activities remaining within the I-cell fibroblasts are localized in the lysosomes, analogous to normal cells. Characterization of the carbohydrate-dependent properties of the lysosomal N-acetyl-beta-D-hexosaminidase revealed that the I-cell and normal enzymes do not contain a significant proportion of neuraminidase-susceptible sialic acid residues, interact poorly with the beta-galactose-specific lectin Ricinus communis and are highly sensitive to endohexosaminidase H treatment, indicating that the oligosaccharide units of both the I-cell and normal lysosomal N-acetyl-beta-D-hexosaminidase are predominantly of the high mannose type. The I-cell and normal lysosomal N-acetyl-beta-D-hexosaminidase, however, differed in their endocytotic properties. In contrast to the high rate of endocytosis of the normal lysosomal enzyme (7.8%/mg/h), the I-cell type 1 lysosomal enzyme failed to be endocytosed into Sandhoff cells indicating an absent or altered phosphohexyl recognition marker on the I-cell enzyme. Examination of the normal extracellular N-acetyl-beta-D-hexosaminidase revealed the presence of predominantly high mannose-type oligosaccharide units, similar to the corresponding lysosomal enzyme, although properties typical of complex-type oligosaccharide chains were also evident. In contrast, the secreted I-cell enzyme revealed the presence of oligosaccharide units predominantly of the complex type indicating that the I-cell N-acetyl-beta-D-hexosaminidase has had high mannose-type oligosaccharide chains modified to complex-type probably in the Golgi or GERL region prior to secretion from the cell.

Acetylglucosaminidase↗
PubMed1980

Human lysosomes can be purified from diploid skin fibroblasts by free-flow electrophoresis.

Human diploid fibroblasts underwent lysis when resuspended in isotonic sucrose. After preparation of a granular fraction by differential centrifugation, lysosomes were almost completely purified by free-flow electrophoresis. Electron micrographs of the final fraction of fibroblast lysosomes (about 25-fold purified) showed mostly secondary lysosomes having an appearance identical to those in intact cells. There was no indication that the purification steps selectd for any lysosomal subpopulation. The lysomal nature of the isolated organelles was confirmed by cytochemical staining for acid beta-glycerophosphatase. As judged by a 92% structure-linked latency of beta-N-acetylglucosaminidase in the final fraction, the structural integrity of the isolated lysosomes was unaffected by the purification procedure.

Cell Fractionation↗
PubMed1979

Oculo-neural involvement in an enzymatically proven case of Niemann-Pick disease type B.

Niemann-Pick disease type B was diagnosed clinically and enzymatically in a 4 years old girl presenting with hepatosplenomegaly, diffuse interstitial infiltrations of both lungs on chest roentgenograms, and foam cells in the bone marrow aspirate. Intelligence and neurological examinations were normal. Spingomyelinase activity was almost totally deficient in leukocytes and cultured skin fibroblasts. Unexpectedly, fundoscopy revealed oculo-neural involvement with a reddish-brown spot of the macula comparable to but differing in some respects from the classic cherry-red spot found in neurolipidoses. By definition patients with type B Niemann-Pick disease should have no cerebral or oculo-neural involvement. Two comparable cases have been described in the literature. The prognosis of this special type is not yet known. For classification--and especially for genetic counselling--it seems important to include the possibility of oculo-neural involvement in the diagnosis of Niemann-Pick disease type B.

Child, Preschool↗
PubMed1979

Characterization of virus-like particles produced by an influenza A virus.

The influenza strain 413 1,1 segregated as a stable recombinant during passage of the isolate 19/N which was obtained after double infection of chick embryo fibroblasts by virus N and the fowl plague virus (FPV) mutant ts 19. Its gene constellation was determined by molecular hybridization. Upon infection of chick embryo cells by this recombinant strain, two particle populations of high (H) and low (L) buoyant densities were produced. By biological and biochemical parameters, the H-population (delta = 1.22 g/cm3) cannot be distinguished from standard infectious influenza virus. In contrast, the noninfectious L-particles (delta = 1.14 g/cm3) lack all virus-specific glycoproteins (HA, NA) as well as the matrix protein M and are visualized by electron microscopy as spikeless particles. Significant changes in the quantitative composition of the phospholipid bilayer are evident as compared to the H-particles. In addition to the previously characterized eight genes both populations contain a variety of smaller RNA fragments which hybridize with complementary RNA and presumably represent degradation products of full-length genes.

Animals↗
PubMed1979

[Adolescent cystinosis. Review of the literature and case report (author's transl)].

A case of adolescent cystinosis in a 17 1/2 year-old boy is reported. The metabolic disorder was diagnosed at the age of 13 years. Cystine was demonstrated in cornea and bone marrow and was increased in fibroblasts (3.64 nMol 1/2-cystine/mg protein). The renal lesions were characteristic of mesangioproliferative glomerulonephritis. The rate of detoriation in renal function increased from 1.5 to 6.6 mg/100 ml serum creatinine during the time of follow up. As well as the parents one brother (0.51 nMol 1/2-cystine/mg protein) appears to be a heterozygote carrier of the cystinosis gene. The striking features in adolescent cystinosis were shown by a review of the literature and the present case report.

Adolescent↗
PubMed1978

The structure of the Rous sarcoma virus glycoprotein complex.

The viral envelope glycoprotein gp85 is released from purified Rous sarcoma virus by treatment with 2-mercaptoethanol, while the second surface antigen gp35 remains associated with the membrane of intact virus particles. The data represented substantiate and extend previous observations on the Rous sarcoma virus glycoprotein complex.

Avian Sarcoma Viruses↗
PubMed1978

Minor nucleic acids in influenza virus.

A nucleic acid fraction consisting of RNA and DNA sequences with an apparent mol. wt. of 1.4 to 1.5 x 10(6) is present in minor amounts in purified influenza virus. The RNA is virus-specific and in the case of fowl plague virus (FPV) contains sequences of genes 2 and 7 which code for one of the proteins constituting the polymerase complex and for the matrix protein respectively.

DNA↗
PubMed1978

Bovine and ovine leukemia viruses. I. Characterization of viral antigens.

A comparative study on several virus-specific antigens of bovine and ovine leukemia viruses is presented. In addition to the major immunologically reactive, nonglycosylated antigen p21, which has a molecular weight of 21,000, both viruses share two glycoproteins of apparent molecular weights of 60,000 (gp60) and 32,000 (gp32), respectively. Immunological cross-reaction suggests that ovine and bovine leukemia viruses are genetically highly related.

Animals↗
PubMed1978

Effects of dexamethasone on the morphogenesis of two mutants of Rous sarcoma virus.

Japanese quail cells transformed by the replication-defective, Bryan high-titer strain of Rous sarcoma virus, BH RSV(-)Q, clone 3, revealed intracytoplasmic A-type particles after dexamethasone treatment. In the absence of dexamethasone, or when superinfected with a helper virus in the presence or absence of dexamethasone, no such particles were observed. Chick embryo cells (CEC) infected with a temperature-sensitive sarcoma virus mutant, LA 334, coordinately defective for transformation and viral replication, showed abnormal accumulation of viral core substances and aberrant budding at the non-permissive temperature (41 degrees). CEC infected with LA 334 and treated with dexamethasone at 41 degrees resulted in more extensive accumulation of abnormal budding without increased release of viral particles. Dexamethasone, however, did not lead to abnormal morphogenesis of virus under permissive conditions. The selective effects of dexamethasone on the morphogenesis of these two mutants of avian sarcoma virus are discussed.

Animals↗
PubMed1978

Transformation of skin fibroblast cells of a cystinotic patient by simian virus 40: evidence for an establishment of a permanent cell clone which retains the original metabolism defect.

Human skin fibroblast cells derived from a juvenile patient with nephropathic cystinosis were transformed by simian virus 40. Transformed cell clones were isolated and established in tissue culture. In comparison to the parental cystinotic cells, the newly isolated, transformed cell clones had a higher plating efficiency, a modal chromosome number of 68, grew in soft agar, and showed a nuclear immunofluorescence typical for SV 40-specific tumor (T) antigen. The content of intracellular, unbound cystine in the transformed cell clone was of the same level (6.1 nmol 1/2 cystine/mg protein) as in the parental cystinotic cells (7.4 nmol). Control cells (SV 80 and WI-38) contained normal levels of cystine (0.31 and 0.47 nmol 1/2 cystine/mg protein). The growth characteristics make the transformed cystinotic cell clone suitable for large scale preparation of cellular constituents, i.e. lysosomes which seem to be affected in cystinotic patients.

Adolescent↗