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Biomedical subjects

R Verheijen

Publications and source records attributed to R Verheijen.

At least 19 recordsLinked to original sources
PubMed2002

Remifentanil-sevoflurane anaesthesia for laparoscopic cholecystectomy: comparison of three dose regimens.

The objective of this study was to determine a dosing regimen for remifentanil-sevoflurane anaesthesia that achieves an optimal balance between quality of anaesthesia and time to recovery. Patients undergoing elective laparoscopic cholecystectomy were randomly allocated to receive 0.4, 0.8 or 1.2 MAC (minimal alveolar concentration) of sevoflurane combined with remifentanil as required to maintain stable anaesthesia. For induction of anaesthesia, the remifentanil dose was 25 microg x kg(-1) x h(-1) and the mean propofol dose which was required to obtain loss of consciousness was 1.59 mg x kg(-1). During the maintenance phase, the mean remifentanil dose was 16.0, 14.1 and 13.0 microg x kg(-1) x h(-1) for the 0.4, 0.8 and 1.2 MAC groups, respectively. The mean sevoflurane maintenance dose was 0.91, 1.24 and 2.1% end-tidal for the 0.4, 0.8 and 1.2 MAC groups, respectively. The incidence of somatic responses was significantly higher in the 0.4 MAC sevoflurane group. Recovery times were significantly faster in the 0.4 compared to the 0.8 and 1.2 MAC groups and in the 0.8 compared to the 1.2 MAC group. The combination of 14 microg x kg(-1) x h(-1) remifentanil and 1.24% end-tidal sevoflurane achieved the optimal balance between the quality, and recovery from anaesthesia.

Adult↗
PubMed2002

Model-based administration of inhalation anaesthesia. 4. Applying the system model.

BACKGROUND: We developed and tested a simple dosing strategy for rapid induction with isoflurane followed by maintenance under minimal-flow conditions, that is 0.5 litre min(-1) total fresh gas flow (FGF). An end-expired concentration was to be achieved within 5 min in a desired therapeutic window, that is 0.8-1.1 vol%, and to be maintained within it for at least 30 min. METHODS: With our new model we computed a three-stage regimen using one fixed vaporizer setting: 3 vol% isoflurane in a FGF of 3 and 1.5 litre min(-1), each for 3 min, and 0.5 litre min thereafter. The ratio of nitrous oxide:oxygen was, consecutively, 2:1, 2:1, and 2:3. We evaluated this scheme in 58 adult patients (body mass 74 (SD 13) kg), mostly during eye and ear, nose, and throat surgery. RESULTS: Measured oxygen (33-45 vol%) and nitrous oxide concentrations (66-50 vol%) evolved in accordance with those computed. In five patients with a median of body mass 92 kg (range 76-126 kg), inspired oxygen concentrations decreased to less than 30 vol%. End-expired isoflurane concentration entered the window after 2 min (range 1.0-5.67 min) and attained its maximum, that is 0.96 vol% (0.8-1.2 vol%), after 3.45 min (1.67-6.33 min). The mean end-expired concentration was in the desired window from 3-60 min and an average of 72% of individual measurements were within the window from 3-30 min. The scheme was adapted in six patients (excluded from analysis) because of hypotension. CONCLUSION: The regimen is easily remembered, reliable, and lends itself to alternative strategies, but must be guided by the monitoring of gas and vapour concentrations and haemodynamic variables.

Adolescent↗
PubMed2001

Direct biosensor immunoassays for the detection of nonmilk proteins in milk powder.

The low prices of some nonmilk proteins make them attractive as potential adulterants in dairy products. An optical biosensor (BIACORE 3000) was used to develop a direct and combined biosensor immunoassay (BIA) for the simultaneous detection of soy, pea, and soluble wheat proteins in milk powders. Affinity-purified polyclonal antibodies raised against the three protein sources were immobilized in different flow channels (Fcs) on the biosensor chip (CM5). Dissolved milk powders were injected (20 microL injections at 20 microL min(-1)) through the serially connected Fcs, and the antibody-bound plant proteins were detected directly. The total run time between samples, including a regeneration step with 5 microL of 10 mM HCl, was 5 min. The limits of detection in milk powder were below 0.1% of plant protein in the total milk protein content. The antibodies also recognized some proteins from other plant sources, which made this BIA even more suitable as a broad screening assay for nonmilk proteins.

Animals↗
PubMed2000

[Human papillomavirus and screening for cervical cancer: state of art and prospects].

More than 99% of all cervical cancers contain high risk HPV. Only a persistent infection with high risk HPV of the cervical epithelium results in cervical cancer. Because the risk of cervical cancer is identical for all different HPV types, tests which detect all 14 high risk HPV types at one time are sufficient for clinical management. Testing for hr-HPV is mandatory for women with mild dyskaryosis and for the follow-up of women treated for CIN lesions. Based on efficiency to detect CIN3 and cervical cancer and preliminary cost benefit analysis, the combination of a high risk HPV test in conjunction with a cervical smear appears to be the best way of cervical cancer screening. A definite point of view on using high risk HPV testing for primary screening for cervical cancer will be obtained after the completion of a randomized trial of 44,000 women, in which the efficiency to detect CIN3 and cervical cancer by high risk HPV testing in conjunction with a cytomorphological smear is compared with screening by classical cytology.

Adult↗
PubMed1998

Development of a one step strip test for the detection of sulfadimidine residues.

The one step strip test described is a competitive immunoassay in which the detector reagent consists of colloidal gold particles coated with affinity purified polyclonal anti-sulfadimidine (SDD) antibodies. The capture reagent in the assay is an SDD-ovalbumin conjugate which is immobilised on the lateral flow membrane of the test device. In the test procedure, 150 microliters (four drops) of a liquid sample (buffer, urine or milk) are brought into the sample well of the test device and allowed to migrate over the membrane. The more analyte present in the sample, the more effectively it will compete with the SDD immobilised on the membrane for binding to the limited amount of antibodies of the detector reagent. A sufficient amount of SDD in the sample will therefore prevent the binding of the detector reagent to the SDD immobilised on the membrane. Therefore, a positive sample will not show a test line in the read-out zone. With spiked buffer or calf urine this was obtained at a level of > 10 ng ml-1 of SDD and with spiked (diluted) fresh cow milk at a level > 20 ng ml-1 of SDD. At these levels, the test is applicable only as a qualitative assay. The presence or absence of a test line indicates lower or higher levels of SDD, respectively. The major advantages of the one step strip test are that results can be obtained within 10 min and that all reagents are included in the test device.

Animals↗
PubMed1996

[Intrathecal administration of morphine and bupivacaine in the treatment of severe pain in chronic pancreatitis].

A 25-year-old male with idiopathic chronic pancreatitis suffered from severe pain not reacting to medical therapy. Intractable pain persisted after the following procedures: subtotal resection of the pancreas, interpleural administration of bupivacaine, epidural administration of bupivacaine, and thoracoscopic sympathectomy. Eventually, adequate pain relief was achieved with intrathecal administration of morphine and bupivacaine. An infusion pump, externally controlled by radiotelemetry, was implanted subcutaneously for intrathecal drug administration. With this pump the patient was fully ambulant. Intrathecal administration of morphine and bupivacaine through an implanted pump is a possible new technique for pain management in chronic pancreatitis.

Adult↗
PubMed1994

Screening for autoantibodies to the nucleolar U3- and Th(7-2) ribonucleoproteins in patients' sera using antisense riboprobes.

In this study we report the detection of autoantibodies to the nucleolar U3- and Th(7-2) ribonucleoprotein (RNP) particles in sera from patients with connective tissue diseases. The method described employs radioactively labelled antisense U3- and Th RNA which are hybridized to immunoprecipitated U3- or Th RNA from a HeLa cell extract. Of the 66 sera that were screened with this method seven sera (11%) precipitated only Th RNP, 16 sera (24%) precipitated only U3 RNP and 4 sera (6%) precipitated both U3- and Th RNP. Both anti-U3 RNP and anti-Th RNP activity appeared to be mostly associated with scleroderma or scleroderma-associated diseases. Using this method we also showed that some of the Th RNP particles in a cell extract are associated with the La autoantigen. We conclude that for the identification of immunoprecipitated RNAs this method is very sensitive and provides unambiguous data.

Antibodies, Antinuclear↗
PubMed1994

Multimedia as part of the HELIOS SEE.

This paper discusses the approach taken in HELIOS towards defining a distributed multimedia component as part of the HELIOS Software Engineering Environment (SEE). A user requirements study, performed at the beginning of this project, led to a functional distinction between permanent kernel components and optional service components. The multimedia components cover audio and video capture, replay and synchronization. Medical imaging is considered as a separate service, developed by the German partner of the HELIOS consortium.

Computer Graphics↗
PubMed1992

Analysis of an immunodominant epitope of topoisomerase I in patients with systemic sclerosis.

In this paper an immunodominant epitope of Topoisomerase I is described. An epitope expression sublibrary was constructed from Topoisomerase I cDNA. The subclones were screened with an antiserum from a patient with systemic sclerosis (SSc). The positive clones defined one immunodominant B cell epitope (epitope III), which was located at the carboxyterminal part of the protein. The epitope, 52 amino acids in length, neither contains the p30gag sequence nor the suggested active site Tyr-723, both presumed antibody recognition sites. More than 70% of our anti-TopoI sera recognize this epitope III, indicating that it is a major recognition site of the anti-TopoI autoantibodies in SSc sera. DNA relaxation experiments show that all sera that recognize epitope III and most sera with antibodies to other epitopes inhibit Topoisomerase I activity.

Autoantibodies↗
PubMed1992

Molecular cloning of a major CENP-B epitope and its use for the detection of anticentromere autoantibodies.

An enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of anticentromere autoantibodies in sera of patients with suspected or manifest rheumatic diseases. The antigen source used in this assay consists of the recombinant protein of glutathione S-transferase (GST) fused to the last 60 C-terminal amino acid residues of the major centromere protein CENP-B. Although this CENP-B segment is only a small part of the complete polypeptide, we show that it constitutes an important autoimmune antigenic domain which is recognized by all patient sera in which ACA can be detected using the immunoblotting technique with a HeLa S3 nuclear protein extract as antigen source.

Amino Acid Sequence↗
PubMed1992

A recombinant topoisomerase I ELISA: screening for IgG, IgM and IgA anti-topo I autoantibodies in human sera.

An ELISA for the detection of anti-topoisomerase I autoantibodies in sera from patients with suspected or manifest rheumatic diseases is described. The antigen source used in this assay consists of a recombinant protein containing the last 695 C-terminal amino acid residues of human topoisomerase I (topo I). The sensitivity of the assay was 61%, while the specificity was more than 98%. Using this ELISA, 47 sera from scleroderma patients and immunopositive for anti-topo I antibodies, were screened for the presence of the isotypes IgG, IgA and IgM to topo I. Our finding that relatively high levels of IgA antibodies to topo I are present in most of the sera tested is consistent with the results of Hildebrandt et al. [1]. In addition, it is demonstrated that the IgG and IgA antibodies in a serum may recognize different epitope regions on the topo I polypeptide.

Autoantibodies↗
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↗