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Biomedical subjects

J Brouwer

Publications and source records attributed to J Brouwer.

At least 109 records · Page 6Linked to original sources
PubMed1984

Determination of lysozyme in serum, urine, cerebrospinal fluid and feces by enzyme immunoassay.

Conjugates of human lysozyme and horseradish peroxidase (HRP) were prepared by means of the heterobifunctional reagent N-succinimidyl 3-(2-pyridyldithio) propionate. A conjugate containing 2 mol HRP/mol lysozyme was isolated by gel filtration and used as a labeled antigen in competitive enzyme immunoassays, in which anti-lysozyme rabbit IgG had been bound to wells of microtiter plates. The assay can detect as little as 1 microgram lysozyme/l. The following reference intervals have been established: 950-2450 micrograms/l for serum, 1.7-123 micrograms/l for urine, 17.6-118 micrograms/l for cerebrospinal fluid and 0.04-1.5 microgram/g for feces.

Chromatography, Gel↗
PubMed1983

Effect of pKM101 on cell killing and specificity of mutation induction by cis-diaminedichloroplatinum(II) in Escherichia coli K-12.

Cell killing and mutation induction in the lacI gene of Escherichia coli by cis-Pt(NH3)2Cl2 were studied in cells with different repair capacities, with and without pKM101. The presence of the plasmid pKM101 made repair-proficient cells more susceptible to killing by cis-Pt(NH3)2Cl2 and strongly enhanced mutation induction by that compound. Both effects were shown to be dependent upon excision repair. Characterization of the induced mutations in the lacI gene after cis-Pt(NH3)2Cl2 treatment of E. coli cells, by the LacI system, revealed that the mutagenic specificity of the Pt compound was strongly influenced by the presence of the pKM101 plasmid. With pKM101, 23% of the induced amber and ochre mutations resulted from substitutions at AT base pairs, whereas these mutations were hardly induced in cells without pKM101. These results suggest that pKM101-induced repair differs from normal SOS repair.

Cisplatin↗
PubMed1982

Influence of temperature on platinum binding to DNA, cell killing, and mutation induction in Escherichia coli K-12 cells treated with cis-diamminedichloroplatinum(II).

Cell killing and specificity of mutation induction by treatment of Escherichia coli K-12 cells with cis-Pt(NH3)2Cl2 at various temperatures have been studied. Survival experiments show that the cell killing by cis-Pt(NH3)2Cl2 is enhanced with increasing temperature. This effect is explained by an increase in the amount of platinum bound to the DNA. The binding is the same in repair-proficient and in repair-deficient cells. However, the mutation induction in the lacI gene is much more strongly enhanced than could be expected from the increased platinum binding. This phenomenon is attributed to a different distribution of the induced lesions by cis-Pt(NH3)2Cl2 at various temperatures and not to an aberrant excision repair. Analysis of the induced lacI mutants revealed an increase in the percentage of nonsense mutants at higher temperature. Among the nonsense mutations, base-pair substitutions at GAG and particularly at GCG sequences are enhanced by the increasing temperature. The results are in agreement with our hypothesis that local denaturation of DNA, known to be promoted at higher temperature, is necessary for the formation of intrastrand cross-links at two guanine bases separated by a third base.

Cell Survival↗
PubMed1981

Influence of DNA-repair deficiencies on MMS- and EMS-induced mutagenesis in Escherichia coli K-12.

The mutagenic effects of the alkylating agents, MMS and EMS, were studied by measuring the reversion of an arg (ochre) mutation in various DNA-repair-deficient strains. When compared with the wild-type strain, EMS-induced mutagenesis was reduced in the recA13 strain but not in the lexA3 strain. MMS-induced mutagenesis was reduced to background levels in the recA13 strain and reduced to intermediate levels in the lexA3 strain. The umuC36 strain showed intermediate levels of mutagenesis with both mutagens which suggests that a substantial portion of both MMS- and EMS-induced mutagenesis depends upon this component of the error-prone "SOS" repair pathway. The uvrD101, recL152 and recF143 mutations produced increased levels of MMS-induced reversion but had no effect upon the levels of EMS-induced mutagenesis, suggesting that the pathways affected by these genes may play a role in the error-free repair of MMS but not EMS damage. In contrast, a large increase in the level of mutagenesis was noted in a delta uvrB101 mutant with EMS but not MMS. This hypermutability with EMS was also seen in uvrA6, uvrB5 and uvrC34 mutant strains and suggests a role for excision in the error-free repair of ethylation but not methylation damage to DNA.

DNA Repair↗
PubMed1981

Base-pair substitution hotspots in GAG and GCG nucleotide sequences in Escherichia coli K-12 induced by cis-diamminedichloroplatinum (II).

Cell killing and mutation induction by cis- and trans-Pt(NH3)2Cl2 in Escherichia coli were examined by studying forward mutagenesis in the lacI gene in cells with different repair capacities. Survival experiments showed that repair-proficient cells were slightly more sensitive for the cis isomer than for the trans isomer, whereas repair-deficient RecA and UvrB cells were extremely sensitive only for the cis compound. cis-Pt(NH3)2Cl2 induced mutagenesis in both wild-type cells and RecA cells but not in UvrB cells; whereas no detectable mutagenesis was induced by treatment with the trans compound. Examination of the nature of the mutations induced by cis-Pt(NH3)2Cl2, by using the LacI system, revealed that base-pair substitutions leading to nonsense mutants are only induced in wild-type cells, suggesting that the intact products of both the uvrB and the recA gene are necessary for the repair responsible for this type of mutagenesis. Investigation of the nonsense mutants reveals that 70% of these mutations result from GC leads to TA or GC leads to AT substitutions at sites where the guanine is part of a GAG or GCG sequence. These results are discussed in relation to existing theories on the interaction between Pt compounds and DNA. A model for Pt--DNA adducts, leading to base-pair substitutions, is proposed.

Base Composition↗
PubMed1980

Analysis of the origin of charge heterogeneity of Rauscher murine leukaemia virus p30.

Preparations of the 30 X 10(3) mol. wt. protein (p30) of Rauscher murine leukaemia virus (R-MuLV) which had been purified to homogeneity as judged by gel electrophoresis in the presence of SDS and by amino-terminal amino acid analysis, showed considerable isoelectric heterogeneity. It was found that R-MuLV p30 polypeptide chains are easily converted in vitro into chains with more acidic isoelectric points. R-MuLV p30 polypeptides with different isoelectric points displayed the same set of 125I-labelled tryptic peptides. It is concluded that the charge heterogeneity of R-MuLV p30, as revealed in isoelectric focusing experiments, is not caused by genetic heterogeneity of the virus genome but by post-translational modification.

Animals↗
PubMed1980

Detection of antibodies cross-reactive with type C RNA tumor viral p30 protein in human sera and exudate fluids.

Human sera and human exudate fluids were surveyed for the presence of antibodies cross-reacting with a type C viral protein with a molecular weight of 30,000 (p30). Antibodies cross-reactive with type C viral p30 were concentrated by means of affinity chromatography using Sepharose beads to which disrupted Simian sarcoma virus or Rauscher murine leukemia virus p30 had been coupled. Eluates obtained from the affinity beads were tested for activity against Rauscher murine leukemia virus p30, Simian sarcoma virus p30, and endogenous feline virus RD-114 p30 by radioimmunoprecipitation. Of 57 eluates tested, 29 showed activity against type C viral p30. A number of eluates were also tested for anti-p30 activity by a visual microcytotoxicity assay. Of 11 eluates positive in the radioimmunoprecipitation assay, five were also positive in the microcytotoxicity assay.

Animals↗
PubMed1979

The quantitation of cell surface antigens by antibody-complement mediated cytotoxicity: application to murine leukemia virus-infected mouse cells.

51Cr-antibody-complement mediated cytotoxicity (ACC) can be used to quantify nanogram amounts of cell surface antigens. When pure antigen is available for calibration, inhibition of ACC by known amounts of antigen and by whole cells yields an estimate of the number of antigenic equivalents per cell. ACC is more suitable for this purpose than radioimmunoprecipitation assay. By ACC the number of antigenic equivalents of the oncornaviral proteins gp70 and p30 has been determined on the surface of various cells infected with Rauscher and Gross murine leukemia viruses.

AKR murine leukemia virus↗
PubMed1979

Chemical characterization of Rauscher leukaemia virus proteins.

The proteins of Rauscher murine leukaemia virus (R-MuLV) were characterized by amino acid analyses and by determination of their mol. wt. by gel filtration on cross-linked Sepharose 6B in 6M-guanidine hydrochloride (GuHCl). Molecular weights of 56,000, 29,000, 15,000, 10,500 and 7,600 were found for gp70, p30, p15, p12 and p10 respectively. The amino acid compositions of these proteins and of p12E have been determined. The amino acid compositions of the p10 polypeptides of Rauscher-MuLV and Moloney-MuLV are very similar as are those of the p30 polypeptides, whereas the amino acid compositions of the p12 polypeptides differ considerably. P12E contains the highest percentage of hydrophobic amino acid residues. Among the gag-gene coded proteins, p15 contains the highest percentage of hydrophobic amino acid residues while p12 and p10 contain the lowest.

Amino Acids↗
PubMed1979

Messenger ribonucleoprotein complexes in human KB cells infected with adenovirus type 5 contain tightly bound viral-coded '100K' proteins.

Late after infection of KB cells with adenovirus 5 an extra protein becomes associated with messenger ribonucleoprotein particles present in the polysomes. This protein has a molecular weight of 100000 and is identical to the virus coded '100K' protein found previously. The extra protein is firmly attached to the messenger ribonucleoprotein complexes. Its binding resists exposure to high salt concentrations as used in puromycin/high-salt dissociation and equilibrium centrifugation in Cs2SO4 gradients. In this respect it resembles the binding of two other proteins of Mr 74000 and 48000 which are commonly found in messenger ribonucleoprotein particles of various eukaryotic cells. The identity between the messenger ribonucleoprotein protein of Mr 100000 and the "100K' protein present in the soluble part of the cytoplasm was established by sodium dodecylsulphate/polyacrylamide gel electrophoresis, isoelectric focusing and peptide mapping after limited proteolysis with Staphylococcus aureus protease.

Adenoviruses, Human↗
PubMed1976

Condyloma-like penis carcinoma.

A squamous cell carcinoma is described which showed clinical and histological features of condyloma acuminatum on the glans penis of a 43-year-old man.

Adult↗