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Biomedical subjects

H Steen

Publications and source records attributed to H Steen.

At least 19 recordsLinked to original sources
PubMed2001

[Complaints in orthopedics reported to the Norwegian Patient Compensation System 1993-99].

BACKGROUND: The Norwegian Patient Compensation System (NPCS) was started up in January 1988. By the end of 1999, a total of 15,552 complaints had been received. This paper reviews the outcome of the complaint procedures in the field of orthopaedics. MATERIAL AND METHODS: From 1993 to 1999, the NPCS assessed a total of 8,520 complaints of which 4,041 (47%) were in orthopaedics. On the basis of abstracts of these cases, we retrieved more detailed information. RESULTS: Over the period, 39% of orthopaedic complaints resulted in compensation, with a decline from 45% in 1993 to 32% in 1999. 328 orthopaedic patients were awarded compensation on the basis of infection; they constituted 8% of all compensated claims and 21% of all compensated orthopaedic claims. These ratios remained fairly constant throughout the period. Compensation was given to 291 patients with loosening of prostheses following use of Boneloc cement; these cases represented 7% of all orthopaedics claims and 18% of all compensated claims. Complaints were most numerous in 1996 and 1997; this reflected the use of this cement in the early 1990s. Rejected complaints were appealed with increasing frequency; in 1999, 46% of all NPCS cases were appealed, 33% of all orthopaedic cases. Rejections overruled following appeal were within a range of 16% (1994) and 11% (1995). When initial rejections overruled on appeal are included, the total compensation-to-claims ratio increases from 39% to 41%. INTERPRETATION: The high number of complaints in orthopaedics probably reflects the high frequency of musculoskeletal disorders in the population. It is to be hoped that evaluation of treatment injuries will result in a higher quality of patient treatment.

Databases, Factual↗
PubMed2001

[Analysis of 700 orthopedic complaints reported to the Norwegian Patient Compensation System].

BACKGROUND: In the 1993-99 period, the NPCS reached decisions on 4,041 orthopaedic injury cases. This paper reviews the complaints lodged. MATERIAL AND METHODS: We have analysed data from 700 randomly selected cases in order to elucidate the reasons for complaint. RESULTS: Complaints were lodged against all types of hospitals and primary health care providers. The most frequent primary diagnosis were osteoarthritis of the hip, lumbar disc herniation, and various fractures. Complaints were most commonly related to faulty treatment, continued pain, nerve injuries, reduced function, mistaken diagnosis, malposition of bone or joint, and infection. 84% of complaints were related to treatment and to operative treatment in particular. In 209 cases (30%), the complaints were heard. Of these 209, 43% were heard because of the treatment given, 21% because of infection, 18% because of diagnostic fault, and 6% because of defective follow-up. 491 complaints were rejected; in 70% of them because the injury was acceptable according to general rules, in 19% because the basic disorder had caused the injury, and in 7% because there was in fact no injury. INTERPRETATION: In our opinion, better knowledge about treatment injury cases represents valuable information that contributes to a higher quality of care.

Adolescent↗
PubMed2001

Detection of tyrosine phosphorylated peptides by precursor ion scanning quadrupole TOF mass spectrometry in positive ion mode.

Phosphorylation is a common form of protein modification. To understand its biological role, the site of phosphorylation has to be determined. Generally, only limited amounts of phosphorylated proteins are present in a cell, thus demanding highly sensitive procedures for phosphorylation site determination. Here, a novel method is introduced which enables the localization of tyrosine phosphorylation in gel-separated proteins in the femtomol range. The method utilizes the immonium ion of phosphotyrosine at m/z 216.043 for positive ion mode precursor ion scanning combined with the recently introduced Q2-pulsing function on quadrupole TOF mass spectrometers. The high resolving power of the quadrupole TOF instrument enables the selective detection of phosphotyrosine immonium ions without interference from other peptide fragments of the same nominal mass. Performing precursor ion scans in the positive ion mode facilitates sequencing, because there is a no need for polarity switching or changing pH of the spraying solvent. Similar limits of detection were obtained in this approach when compared to triple-quadrupole mass spectrometers but with significantly better selectivity, owing to the high accuracy of the fragment ion selection. Synthetic phosphopeptides could be detected at 1 fmol/microL, and 100 fmol of a tyrosine phosphorylated protein in gel was sufficient for the detection of the phosphorylated peptide in the unseparated digestion mixture and for unambiguous phosphorylation site determination. The new method can be applied to unknown protein samples, because the identification and localization of the modification is performed on the same sample.

Amino Acid Sequence↗
PubMed2001

Molecular patterning of the oikoplastic epithelium of the larvacean tunicate Oikopleura dioica.

Appendicularia are protochordates that rely on a complex mucous secretion, the house, to filter food particles from seawater. A monolayer of cells covering the trunk of the animal, the oikoplastic epithelium, secretes the house. This epithelium contains a fixed number of cells arranged in characteristic patterns with distinct sizes and nuclear morphologies. Certain house structures appear to be spatially related to defined, underlying groups of cells in the epithelium. We show that the house is composed of at least 20 polypeptides, a number of which are highly glycosylated, with glycosidase treatments resulting in molecular mass shifts exceeding 100 kDa. Nanoelectrospray tandem mass spectrometric microsequencing of house polypeptides was used to design oligonucleotides to screen an adult Oikopleura dioica cDNA library. This resulted in the isolation of cDNAs coding for three different proteins, oikosin 1, oikosin 2, and oikosin 3. The latter two are novel proteins unrelated to any known data base entries. Oikosin 1 has 13 repeats of a Cys domain, previously identified as a subunit of repeating sequences in some vertebrate mucins. We also find one repeat of this Cys domain in human cartilage intermediate layer protein but find no evidence of this domain in any invertebrate species, including those for which entire genomes have been sequenced. The three oikosins show distinct and complementary expression patterns restricted to the oikoplastic epithelium. This easily accessible epithelium, with differential gene expression patterns in readily identifiable groups of cells with distinctive nuclear morphologies, is a highly attractive model system for molecular studies of pattern formation.

Amino Acid Sequence↗
PubMed2001

Investigation of tyrosine nitration in proteins by mass spectrometry.

In vivo nitration of tyrosine residues is a post-translational modification mediated by peroxynitrite that may be involved in a number of diseases. The aim of this study was to evaluate possibilities for site-specific detection of tyrosine nitration by mass spectrometry. Angiotensin II and bovine serum albumin (BSA) nitrated with tetranitromethane (TNM) were used as model compounds. Three strategies were investigated: (i) analysis of single peptides and protein digests by matrix-assisted laser desorption/ionization (MALDI) peptide mass mapping, (ii) peptide mass mapping by electrospray ionization (ESI) mass spectrometry and (iii) screening for nitration by selective detection of the immonium ion of nitrotyrosine by precursor ion scanning with subsequent sequencing of the modified peptides. The MALDI time-of-flight mass spectrum of nitrated angiotensin II showed an unexpected prompt fragmentation involving the nitro group, in contrast to ESI-MS, where no fragmentation of nitrated angiotensin II was observed. The ESI mass spectra showed that mono- and dinitrated angiotensin II were obtained after treatment with TNM. ESI-MS/MS revealed that the mononitrated angiotensin II was nitrated on the side-chain of tyrosine. The dinitrated angiotensin II contained two nitro groups on the tyrosine residue. Nitration of BSA was confirmed by Western blotting with an antibody against nitrotyrosine and the sites for nitration were investigated by peptide mass mapping after in-gel digestion. Direct mass mapping by ESI revealed that two peptides were nitrated. Precursor ion scanning for the immonium ion for nitrotyrosine revealed two additional partially nitrated peptides. Based on the studies with the two model compounds, we suggest that the investigation of in vivo nitration of tyrosine and identification of nitrated peptides might be performed by precursor ion scanning for the specific immonium ion at m/z 181.06 combined with ESI-MS/MS for identification of the specific nitration sites.

Affinity Labels↗
PubMed2001

Quadrupole time-of-flight versus triple-quadrupole mass spectrometry for the determination of phosphopeptides by precursor ion scanning.

An API 3000 triple-quadrupole instrument and a QSTAR Pulsar quadrupole time-of-flight (TOF) mass spectrometer were compared for the determination of phosphopeptides by precursor ion scanning in both the positive and negative nanoelectrospray ionization modes. The limits of detection for synthetic phosphopeptides were similar (500 amol microl(-1)) for both types of instruments when monitoring precursors of -79 Da (PO(3)(-)). However, the quadrupole TOF system was approximately fivefold more sensitive (1 fmol microl(-1)) than the triple-quadrupole instrument (5 fmol microl(-1)) when monitoring precursors of 216 Da (immonium ion of phosphotyrosine). The recently introduced Q(2)-pulsing function, which enhances the transmission of fragment ions of a selected m/z window from the collision cell into the TOF part, improved the sensitivity of precursor ion scans on a quadrupole TOF instrument. The selectivity of precursor ion scans is much better on quadrupole TOF systems than on triple quadrupoles because the high resolving power of the reflectron-TOF mass analyzer permits high-accuracy fragment ion selection at no expense of sensitivity. This minimizes interferences from other peptide fragment ions (a-, b-, and y- type) of the same nominal mass but with sufficient differences in their exact masses. As a result, the characteristic immonium ion of phosphotyrosine at m/z 216.043 can be utilized for the selective detection of tyrosine phosphorylated peptides. Our data suggest that, in addition to their superior performance for peptide sequencing, quadrupole TOF instruments also offer a very viable alternative to triple quadrupoles for precursor ion scanning, thus combining high sensitivity and selectivity for both MS and MS/MS experiments in one instrument.

Amino Acid Sequence↗
PubMed2001

The normal development of tibial torsion.

OBJECTIVE: Pathological rotation of the leg is a well-known problem in paediatric orthopaedics. In this study the normal development of tibial torsion during growth was evaluated by computed tomography (CT). DESIGN: Seventy-eight normal individuals (52 children, 26 adults) aged 3-51 years were examined with CT. In axial scans the angle between a line tangential to the posterior part of the femoral condyles and the intermalleolar line, a line through the centre of the lateral and medial malleolus, was measured. The radiation exposure was evaluated and accepted by The National Department for Radiation and the Regional Committee for Ethics in Science. RESULTS: CT showed that the average lateral torsion of the leg at the age of 4 years was 28 degrees with an individual variation of 20 degrees-37 degrees. Later the increase in tibial torsion was on average 1 degrees/year until 10 years of age and, thereafter, 4 degrees until maturity when the mean lateral torsion was 38 degrees (18 degrees-47 degrees). CONCLUSION: Tibial torsion in children mainly develops during the first 4 years of life. After this the increase was of less clinical significance.

Adolescent↗
PubMed2001

Deformation across the zone of callotasis during loading. radiostereometric analysis in a patient with achondroplasia.

The present study demonstrates that high-resolution radiostereometric analysis (RSA) can be used to assess global longitudinal compressive deformation across the callotasis zone during loading. In an achondroplastic patient operated with bifocal lengthening of the tibia by use of the Ilizarov external fixator, the axial compressive intersegmental strain in the proximal lengthening zone under a load of 71% of body weight was 7.7 mm. The proximal lengthening zone was 51.0 mm, and accordingly the overall linear strain across the callotasis was 15.1%. This large strain value found in distraction osteogenesis 6 weeks after end of distraction is not consistent with classical theory of the magnitude of micromotion needed for adequate stimulation of bone formation in fracture healing. The increased axial displacement did not stimulate bone healing and delayed union was observed. This one single observation does not allow for any conclusions to be drawn about the relationship of strain to fracture healing, but further and refined use of the RSA method will certainly improve our understanding of the role of axial strains in distraction osteogenesis.

Achondroplasia↗
PubMed2001

GPMAW--a software tool for analyzing proteins and peptides.

General Protein/Mass Analysis for Windows (GPMAW) is a valuable piece of software for any molecular biologist, biochemist or mass spectrometrist wishing to analyze protein or peptide sequences. All steps from the acquisition of protein sequence from a built-in web interface, to proteolytic digests, theoretical peptide fragmentation, detailed annotation of sequences and secondary structure prediction, can be performed rapidly and intuitively without first having to spend days reading manuals.

Amino Acid Sequence↗
PubMed2001

Similarity between condensed phase and gas phase chemistry: fragmentation of peptides containing oxidized cysteine residues and its implications for proteomics.

Amino acid residues containing thioethers are easily oxidized during protein purification, derivatization, and/or digestion. For instance, oxidation of methionine residues in proteins during SDS-PAGE is commonly observed. Under low energy collision induced dissociation this gives rise to a second series of fragment ion of lower abundance that are shifted by -64 Da when compared to the oxidized methionine-containing fragments. We report here that alkylated cysteine residues can be found in their oxidized form too, indicating that the oxidation of thioethers can occur during and following protein digestion and not only during SDS-PAGE or reduction and alkylation. Collision induced dissociation experiments on the singly- and multiply-charged species reveals that these peptides preferentially undergo elimination reactions that forms a dehydroalanine from the oxidized, alkylated cysteine residue. This contrasts to the less abundant elimination reaction of peptides containing oxidized methionines which cannot form an alpha,beta-unsaturated compound, but parallels the condensed phased chemistry of sulfoxides. The masses of both precursor and product ions are shifted such that these peptides cannot be identified in database searches with current algorithms. Incorporation of this fragmentation pattern is important for the isotope-coded affinity tag approach since this method is based on peptides containing cysteine residues.

Cysteine↗
PubMed2001

Reduced tibial torsion in congenital clubfoot: CT measurements in 24 patients.

We determined leg torsion with CT scans through the femoral condyles and the ankle joints in 24 children (17 boys) with congenital clubfoot. In 16 cases, there was a bilateral clubfoot, in 5 cases it was left-sided and in 3 cases, it was on the right side. These children were compared to 17 healthy boys and 7 girls. The ages of all children ranged between 3 and 12 years. The average external torsion of the leg in the patients with clubfoot was 20 (15) versus 31 (7) degrees in the healthy children (p = 0.002). This study shows that there are great variations in leg torsion in children with congenital clubfoot and, on average, the external torsion is significantly lower than in healthy subjects.

Bone Diseases↗
PubMed2001

Mass spectrometric analysis of a UV-cross-linked protein-DNA complex: tryptophans 54 and 88 of E. coli SSB cross-link to DNA.

Protein-nucleic acid complexes are commonly studied by photochemical cross-linking. UV-induced cross-linking of protein to nucleic acid may be followed by structural analysis of the conjugated protein to localize the cross-linked amino acids and thereby identify the nucleic acid binding site. Mass spectrometry is becoming increasingly popular for characterization of purified peptide-nucleic acid heteroconjugates derived from UV cross-linked protein-nucleic acid complexes. The efficiency of mass spectrometry-based methods is, however, hampered by the contrasting physico-chemical properties of nucleic acid and peptide entities present in such heteroconjugates. Sample preparation of the peptide-nucleic acid heteroconjugates is, therefore, a crucial step in any mass spectrometry-based analytical procedure. This study demonstrates the performance of four different MS-based strategies to characterize E. coli single-stranded DNA binding protein (SSB) that was UV-cross-linked to a 5-iodouracil containing DNA oligomer. Two methods were optimized to circumvent the need for standard liquid chromatography and gel electrophoresis, thereby dramatically increasing the overall sensitivity of the analysis. Enzymatic degradation of protein and oligonucleotide was combined with miniaturized sample preparation methods for enrichment and desalting of cross-linked peptide-nucleic acid heteroconjugates from complex mixtures prior to mass spectrometric analysis. Detailed characterization of the peptidic component of two different peptide-DNA heteroconjugates was accomplished by matrix-assisted laser desorption/ionization mass spectrometry and allowed assignment of tryptophan-54 and tryptophan-88 as candidate cross-linked residues. Sequencing of those peptide-DNA heteroconjugates by nanoelectrospray quadrupole time-of-flight tandem mass spectrometry identified tryptophan-54 and tryptophan-88 as the sites of cross-linking. Although the UV-cross-linking yield of the protein-DNA complex did not exceed 15%, less than 100 pmole of SSB protein was required for detailed structural analysis by mass spectrometry.

Amino Acids↗
PubMed2001

Cardiac troponin T in ST-segment elevation acute myocardial infarction revisited.

Cardiac troponins not only allow for risk stratification and guidance of therapy in unstable angina and non-Q-wave acute myocardial infarction but also may be useful in the diagnostic workup and monitoring of patients with ST-segment elevation myocardial infarction. In clinical practice, troponins are used for confirmation and monitoring of myocardial infarction, noninvasive prediction of reperfusion success after thrombolytic therapy, and noninvasive estimation of infarct size. Accumulating evidence suggests that the measurement of cardiac troponins on admission may represent a relatively novel application that is useful for early risk stratification and prediction of reperfusion success after thrombolysis or primary percutaneous coronary interventions. Potential mechanisms of the predictive power of cardiac troponins are discussed.

Acute Disease↗
PubMed2000

Identification of a novel immunoreceptor tyrosine-based activation motif-containing molecule, STAM2, by mass spectrometry and its involvement in growth factor and cytokine receptor signaling pathways.

In an effort to clone novel tyrosine-phosphorylated substrates of the epidermal growth factor receptor, we have initiated an approach coupling affinity purification using anti-phosphotyrosine antibodies to mass spectrometry-based identification. Here, we report the identification of a signaling molecule containing a Src homology 3 domain as well as an immunoreceptor tyrosine-based activation motif (ITAM). This molecule is 55% identical to a previously isolated molecule designated signal transducing adaptor molecule (STAM) that was identified as an interleukin (IL)-2-induced phosphoprotein and is therefore designated STAM2. Tyrosine phosphorylation of STAM2 is induced by growth factors such as epidermal growth factor and platelet-derived growth factor as well as by cytokines like IL-3. Several of the deletion mutants tested except the one containing only the amino-terminal region underwent tyrosine phosphorylation upon growth factor stimulation, implying that STAM2 is phosphorylated on several tyrosine residues. STAM2 is downstream of the Jak family of kinases since coexpression of STAM2 with Jak1 or Jak2 but not an unrelated Tec family kinase, Etk, resulted in its tyrosine phosphorylation. In contrast to epidermal growth factor receptor-induced phosphorylation, this required the ITAM domain since mutants lacking this region did not undergo tyrosine phosphorylation. Finally, overexpression of wild type STAM2 led to an increase in IL-2-mediated induction of c-Myc promoter activation indicating that it potentiates cytokine receptor signaling.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Minimal influence of facet joint anesthesia on isokinetic muscle performance in patients with chronic degenerative low back disorders.

STUDY DESIGN: Experimental design. OBJECTIVES: To examine the influence of pain reduction after facet joint injections on isokinetic back muscle performance. SUMMARY OF BACKGROUND DATA: Methods for evaluating the effect of facet joint injections vary. Recent studies base their results solely on the patient's subjective opinion and suggest a need for more objective, concrete, and reliable measurements. METHODS: Eighty-seven patients with a degenerative low back disorder (49 women and 38 men; mean age, 48 years; range, 22-79) who had facet joint injections as a part of preoperative evaluation participated. The mean duration of symptoms was 12.3 years (range, 1-45). The patients underwent isokinetic trunk flexor and extensor muscle strength testing at angular velocities of 60 deg/sec and 120 deg/sec. They performed two tests before the facet joint injections (to eliminate learning effect). All patients had bilateral facet joint injections at L5-S1. Those who did not report pain relief had additional injections at L4-L5. The flexion-extension test was repeated 15 minutes after each injection. Pain and fear were registered on visual analog scales. RESULTS: All 87 patients could perform the isokinetic tests. For extension at 60 deg/sec, a significant improvement was found between the two pretests (P < 0.05). Pain increased significantly from the first to the second pretest (P = 0.02), and a significant decrease in pain was found after the first injection (P = 0.0001). Fear decreased between each test, with a significant decrease after the first injection. No significant change was found for the muscle strength measurements after facet joint anesthesia. There were only weak correlations between decrease in pain and alteration in muscle performance, ranging from 0.06 to 0.37. CONCLUSION: Pain reduction after facet joint injections did not influence isokinetic muscle performance in patients with degenerative low back disorders.

Adult↗
PubMed2000

Detection and quantification of neurotensin in human brain tissue by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A method was developed for mass spectrometric detection of neurotensin (NT)-like immunoreactivity and quantification of NT in human brain tissue. The method is based on immunoprecipitation followed by analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The identity of the major component of the immunoprecipitates as neurotensin was confirmed by fragment ion analysis on an electrospray ionization quadrupole time-of-flight instrument. MALDI-TOF-MS quantification of NT was achieved using stable-isotope-labeled NT as the internal standard, yielding an error of less than 5%. The method allowed detection of low-femtomole amounts of NT, staring from low-milligram amounts of lyophilized brain tissue. In addition to NT, several other peptides were detected in the purified samples, most of which, according to their molecular masses, corresponded to fragments of NT. The method is demonstrated with quantification of NT from human hypothalamus tissue, and a comparison is made with results obtained from competitive radioimmunoassay.

Brain Chemistry↗
PubMed2000

Reliability of goniometric measurements and visual estimates of hip ROM in patients with osteoarthrosis.

BACKGROUND AND PURPOSE: Range of motion (ROM) measurements have been included in several hip scores evaluating the results after hip surgery. The clinical procedures of performing these measurements vary and disagreement exists about the accuracy of visual estimatess compared to goniometer measurements. The purpose of this study was to study the reliability of goniometric measurements and visual estimates of hip ROM in patients with osteoarthrosis. METHOD: Hip ROM measurements (abduction, adduction, extension, flexion and internal/external rotation) were recorded by four different teams on the same day and were repeated one week later. Teams 1, 2 and 3 consisted of physiotherapists using standardized goniometric measurements. Team 4 involved an experienced orthopaedic surgeon making the assessments from visual estimates only. Twenty-five patients (6 M, 19 F; mean age 68.5 years, range 46-76 years) with osteoarthrosis of the hip, verified both clinically and radiologically, participated in the study. RESULTS: With the exception of abduction (p = 0.03), there were no significant differences between the measurements recorded on the first and the second occasions for the same teams. The coefficient of variance was 5.5% for flexion (lowest) and 26.1% for extension (highest). Reproducibility was best for flexion. There was also high reliability when all the arcs of motion were summed up (abuction + adduction + extension + flexion + internal/external rotation). With the exception of internal rotation, there were highly significant differences between the teams when two people performed the measurements compared to the values measured by a single individual. Concordance, expressed as the standardized agreement index, between visual estimates made by one individual (the orthopaedic surgeon) and goniometric measurements made by two experienced physiotherapists, were 0.77-0.83 which indicates good agreement. CONCLUSION: The reproducibility of hip ROM measurements was highest for flexion. There was also high reliability when all the six arcs of motion were summed up. Concordance between visual estimates and goniometric measurements indicates good agreement.

Aged↗