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Biomedical subjects

C Mulder

Publications and source records attributed to C Mulder.

80 records · Page 5Linked to original sources
PubMed1973

Cleavage of adenovirus type 2 DNA into six unique fragments by endonuclease R-RI.

The DNA of adenovirus type 2 was cleaved by restriction endonuclease R.RI into six fragments. These fragments were separated by electrophoresis on composite agarose-polyacrylamide gels. Their molecular weights ranged from 1.1 x 10(6) to 13.6 x 10(6), as measured by electron microscopy. Each fragment represented a unique segment of adenovirus type 2 DNA since: (i) the fragments were obtained in equimolar amounts; (ii) the sum of their molecular weights was equal to the molecular weight of complete adenovirus DNA; and (iii) each fragment exhibited a rate of renaturation that was inversely proportional to its size.

Adenoviridae↗
PubMed1972

Specificity of the break produced by restricting endonuclease R 1 in Simian virus 40 DNA, as revealed by partial denaturation mapping.

Superhelical circular (form I) SV40 DNA was converted to linear molecules by the action of a partially purified restriction enzyme of Resistance Transfer Factor-R(1) of Escherichia coli. The resulting linear DNA molecules are full length, as judged by their sedimentation through alkaline sucrose gradient and by direct observation in an electron microscope. Nicked circular (form II) DNA was found as an intermediate in the conversion of form I DNA to linear DNA. Analysis of partial denaturation maps obtained by alkaline denaturation of the unitlength linear molecules showed that the break in SV40 DNA occurred at a specific site on the DNA.

Centrifugation, Density Gradient↗
PubMedDate not supplied

Restrictions upon Epstein-Barr virus infection of the leukemic cell are demonstrated in patients with hairy cell leukemia.

We tested the hypothesis that Epstein-Barr virus (EBV) might actually infect leukemic hairy cells in vivo by examining those cells for the EBV-receptor, EBV nuclear antigen (EBNA) and membrane antigen (MA), for spontaneous transformation and rescue of infectious virus and for presence of EBV genome. EBV-receptors were found on subpopulations of leukemic cells from each of 7 patients with hairy cell leukemia (HCL) tested. MA was present on low numbers (1-5 per cent) of fresh leukemic cells of 7 patients and in some instances occurred with a greater frequency after 3 to 5 days in culture, with or without 12-O-tetradecanoylphorbol-13-acetate. In 11 fresh leukemic cell preparations from 8 HCL patients, no EBNA was demonstrated. However, 2 samples after 4 days in culture expressed low frequencies of EBNA-positive cells. Spontaneous, EBV-positive cell lines were established with a high transformation efficiency from 3 HCL blood samples but not from 8 other specimens. Infectious EBV could be rescued from some hairy leukemic cell preparations by co-cultivation with cord blood lymphocytes. These results demonstrated that leukemic cell populations harbored infectious EBV, that the leukemic cells expressed virus receptors and suggested that a small subpopulation of leukemic cells might become infected in vivo at least transiently and possibly transformed in vitro by EBV. To test for the extent of occult in vivo infection of leukemic cells with EBV, Southern type hybridization studies were performed with a probe for EBV genome (Bam HI W). At a sensitivity level of 0.1 genome per cell, EBV genome was not detected in the leukemic cell populations of 7 patients. We conclude that host defence mechanisms protecting these individuals from EBV also prevent infections of the leukemic cell and/or most hairy leukemic cells are not suitable targets for both infection and transformation.

Antigens, Viral↗
PubMedDate not supplied

Determining reference ('normal') limits in medicine: an application.

We provide an account of a study to assess reference limits for eight routine laboratory determinations at the Academic Hospital of the Free University, Amsterdam and emphasize methodological issues rather than results. We argue that reference limits have use mainly in the first phase of the diagnostic process. Reference and target populations should be grossly comparable, and therefore patients (after slight selection) could well serve as references. However, we found major differences between in- and out-patients, so we suggest that this factor, together with age and sex, be taken into account. To arrive at reliable limits, the size of the reference sample should be at least 100. Laboratory reports should provide percentiles, which enable a more flexible decision than do fixed limits.

Adult↗
PubMedDate not supplied

The beta-core fragment of human chorionic gonadotropin: biochemical background and clinical application.

In this review an overview is given of the possible applications and usefulness of the beta-core fragment of hCG (beta cf-hCG) as an urinary tumor marker. Expression of human Chorionic Gonadotropin (hCG) is an important indicator of malignant transformation. The biochemical background of this glycoprotein hormone and the degradation pathway towards beta cf-hCG is described. There are two main pathways: peripheral degradation in the serum and the renal parenchymal degradation. HCG and its subunits show immunoreactivity and cross-reactivity with other glycoprotein hormones and their subunits. The different "in house" methods to determine beta cf-hCG developed and used by various research institutes are described. In various types of cancer, concentrations of hCG as well as its beta-subunit may be elevated, allowing the clinical use of these substances as a tumor marker. The relation between laboratory outcome and clinical status is assessed, with emphasis on the beta cf-hCG in gynecological malignancies. The limitations of the use of beta cf-hCG as a tumor marker are discussed. The stability of beta cf-hCG may allow distant follow-up in samples sent to the laboratory by mail.

Biomarkers, Tumor↗