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R Verheijen

Publications and source records attributed to R Verheijen.

29 records · Page 2Linked to original sources
PubMed1991

The mutations in the fibronectin gene described in Japanese patients with systemic sclerosis are not present in Dutch patients.

Recently, a mutant fibronectin gene was identified in skin fibroblasts obtained from sclerotic lesions of 7 Japanese patients with systemic sclerosis (SSc). Two point mutations were found adjacent to the cell-attachment tetrapeptide DNA sequence in exon 7 of the fibronectin gene. In the present study, we investigated whether these point mutations are present in the fibronectin gene of Dutch patients with SSc. We were unable to demonstrate the point mutations in the Dutch SSc patients studied.

Base Sequence↗
PubMed1990

A recombinant topoisomerase I used for autoantibody detection in sera from patients with systemic sclerosis.

We report the expression of a cDNA clone encoding 695 carboxyl-terminal amino acids of human DNA topoisomerase I (topoI) in Escherichia coli. More than 96% of the anti-HeLa topoI-positive sera from patients with a connective tissue disease displayed also an immunoreactivity with this recombinant protein (the HTopoA protein). Sera from patients with a definite diagnosis systemic sclerosis and reacting with HeLa topoI, all reacted with the HTopoA protein as well. Sera from patients with systemic sclerosis that did not contain anti-topoI antibodies (about 30% of the systemic sclerosis sera), as concluded from HeLa immunoblot, displayed also no immunoreactivity with our recombinant antigen. By expressing different fragments of HTopoA, we were able to assign at least three different autoimmune epitope regions on the HTopoA protein and we show that over a period of 5 years the amount of anti-topoI antibodies against these regions may fluctuate.

Amino Acid Sequence↗
PubMed1989

Assignment of the gene(s) involved in the expression of the proliferation-related Ki-67 antigen to human chromosome 10.

The antigen recognized by the monoclonal antibody Ki-67 is a proliferation-related nucleolus-associated constituent used as a marker for cycling cells in tumor diagnosis. Antibody Ki-67 reacts with human proliferating cells, but not with hamster and mouse cells. Expression of the Ki-67 antigen was studied in a panel of human-rodent somatic cell hybrids. The results indicate that a gene involved in the expression of the antigen is located on chromosome 10.

Animals↗
PubMed1989

Ki-67 detects a nuclear matrix-associated proliferation-related antigen. I. Intracellular localization during interphase.

Ki-67 is a commercially available mouse monoclonal antibody, which reacts with a nuclear antigen in proliferating cells. The antibody can be used to determine the growth fraction of human tumours in situ and has been shown to be of prognostic importance. In this study it is shown that in interphase cells Ki-67 reacts with an antigen, mainly present in the nucleoli. Confocal scanning laser microscopy and immunoelectron microscopy on human MR65 monolayer cells revealed that this nucleolar antigen is predominantly localized in the nucleolar cortex and in the dense fibrillar components. The Ki-67 antigen appeared to be preserved in nuclear matrix preparations obtained after in situ fractionation of MR65 cells. Despite many efforts, we could not identify the antigen in immunoblotting or immunoprecipitation assays. Testing of cell cultures of different species by means of indirect immunofluorescence revealed that the antibody reacted with human cells and with the Rhesus monkey kidney-derived cell line LLC-MK2.

Antibodies, Monoclonal↗
PubMed1989

Ki-67 detects a nuclear matrix-associated proliferation-related antigen. II. Localization in mitotic cells and association with chromosomes.

In interphase cells the proliferation-associated antigen recognized by monoclonal antibody Ki-67 is almost exclusively located in the nucleoli. When cells at several stages of mitosis were examined for the localization of the Ki-67 antigen, a striking redistribution could be observed. During prophase the distinct nucleolar Ki-67 fluorescence changed to a bright irregular meshwork throughout the nucleoplasm. At metaphase the antigen appeared to be distributed in a reticulate structure surrounding the condensed chromosomes, while at late telophase a punctated staining of the entire nucleoplasm was observed, which preceded the typical nucleolar localization pattern in each of the two daughter cells. Immunolabelling with Ki-67 of metaphase chromosome spreads revealed a circumferential staining of the individual chromosomes. The Ki-67 antigen is preserved in nuclear matrix preparations obtained after in situ fractionation of interphase cells. When mitotic cells were exposed to such treatments, the obtained fluorescence data suggested that the antigen may be part of the chromosome scaffold. Quantification of the Ki-67 fluorescence signal using flow cytometry revealed the highest staining intensities in mitotic cells. Furthermore, it was shown that nutritionally deprived cells became negative for Ki-67.

Antibodies, Monoclonal↗
PubMed1986

Protein composition of nuclear matrix preparations from HeLa cells: an immunochemical approach.

Procedures for the isolation of HeLa S3 nuclear matrices were re-examined with special emphasis on the use of various nucleases and detergents as well as on the ionic strength of the final salt extraction. The protein composition of the resulting nuclear matrix preparations was analysed by one- and two-dimensional gel electrophoresis and found to be extremely reproducible. By means of co-electrophoresis several typical cytoskeletal proteins (actin, vimentin and cytokeratins) and heterogeneous nuclear RNA (hnRNA)-associated core proteins (hnRNP) were shown to be present in such nuclear matrix preparations. The nature of some other protein components was elucidated using two-dimensional immunoblotting and immunofluorescence. For this purpose mouse monoclonal antibodies to cytoskeletal components (vimentin, cytokeratins), small nuclear RNP (70 X 10(3) Mr protein of U1-RNP), hnRNP (C1/C2) and the pore-complex lamina (lamins A, B and C) were used next to human autoimmune sera obtained from patients with connective tissue diseases and directed against the residual nucleoli and the internal fibrillar mass. These antibodies enabled us to identify a number of proteins present specifically in the nuclear matrix and to show that part of the cytoskeletal proteins are still present in the isolated structures.

Cell Nucleus↗
PubMed1986

Distribution of the 70K U1 RNA-associated protein during interphase and mitosis. Correlation with other U RNP particles and proteins of the nuclear matrix.

Earlier studies suggested that the 70K (70 X 10(3) Mr) polypeptide is a nuclear matrix (associated) protein since it is the only U1 RNP-associated antigen that is not released from the nucleus after treatment of the cell with, successively, detergents, DNase I and/or RNase A and high salt. The possibility that the 70K protein functions in the binding of U1 RNP to the nuclear matrix is now further substantiated by the finding that U1 RNP particles that did or did not contain the 70K protein could be isolated, depending on the method of isolation. When U1 RNP particles were obtained by means of sonic disruption of the nucleus they contained the 70K polypeptide, whereas particles that were isolated by extraction at room temperature and a slightly alkaline pH lacked the 70K protein but contained the intact U1 RNA and the other U1 RNA-associated proteins. During interphase the localization of the 70K protein is restricted to the nucleus, giving a dot-like distribution pattern with exclusion of the nucleoli. During prophase to late anaphase the protein is dispersed throughout the entire cytoplasm with the exception of the chromatin regions. Immunofluorescence studies, using a monoclonal anti-70K antibody in combination with human autoimmune sera that react with U1 RNA-associated proteins, demonstrate that the 70K protein is localized in those areas of the cell where other U RNP proteins occur, also during mitosis. Topoisomerase I and nuclear lamins, typical nuclear matrix proteins, show completely different distribution patterns in all phases of the cell cycle. Assembly of the nuclear envelope is attended by the re-formation of the clustered appearance of the 70K antigen. These results suggest that, although associated with the nuclear matrix fraction in interphase cells, the 70K protein remains associated with the U1 RNP particles during cell division.

Animals↗
PubMed1983

In-use evaluation of the Omnicon automated tumor colony counter.

The reproducibility and accuracy of the Omnicon (Bausch and Lomb Inc., Rochester, NY) automated tumor colony counter for counting tumor colonies growing in double layer soft agar is evaluated and the reproducibility is compared with manual tumor colony counting. Replicate within day run-to-run colony counts of the Omnicon show a median correlation coefficient (r) of greater than 0.985, and day-to-day median r of greater than 0.980. In contrast, for manual colony counting, the best intra-observer reproducibility achieved is a r of 0.943 and the best inter-observer reproducibility is a r of 0.831. Analysis of results from individual culture plates counted by the Omnicon on 5 separate days shows a median coefficient of variation of 10% with 77% of the culture dishes showing coefficients of variation of colony counts over 5 days of less than 20%. Counting of culture plates during incubation shows that the Omnicon is counting tumor colonies developing after plating of a single cell suspension.

Animals↗
PubMedDate not supplied

The PENCAN 25-gauge needle: a new pencil-point needle for spinal anesthesia tested in 1,193 patients.

BACKGROUND AND OBJECTIVES: The PENCAN 25-gauge spinal needle is a new pencil-point needle with an inner diameter of 0.32 mm resulting in a relatively high cerebrospinal fluid (CSF) flow. The PENCAN 25-gauge needle was tested for ease of identification of a successful dural puncture, the failure rate of spinal anesthesia, and the incidence of postdural puncture headache (PDPH). METHODS: In a multicenter trial, the needle was tested in patients undergoing spinal anesthesia. A questionnaire evaluated the characteristics of the dural puncture. A second questionnaire was used to assess postspinal side effects (PDPH, atypical headache, audiovisual disturbances). RESULTS: In 1,193 patients, dural puncture was evaluated as easy in 85.2%, as moderate in 6.2%, as difficult in 6.7%, and as impossible in 1.9%. Needle performance was assessed as excellent or satisfactory in 96.9%. In 95.9% of patients, CSF appeared within 2 seconds. A perceptible "click" was noticed in 78.4% of patients. In 1.9%, CSF could not be obtained, because of spine deformities, obesity, or bending of the needle. In 1,166 patients, postpuncture complaints were evaluated, involving 635 women (54.5%), 773 patients (66.3%) under the age of 50 years old, and 170 (14.6%) cesarean deliveries. The overall incidence of PDPH was 1.3% (n = 15). A bloodpatch was needed in five patients. After cesarean delivery the incidence of PDPH was 3.4%, all responding to conservative treatment. Atypical headache and isolated audiovisual disturbances occurred in 7.5% and 1.5% of patients, respectively. CONCLUSIONS: A failure rate of 1.9% together with a 1.3% incidence of PDPH were comparable to other 25-gauge pencil-point needles. The rapid appearance of CSF and a perceptible "click" made prompt recognition of successful dural puncture possible.

Anesthesia, Spinal↗