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Biomedical subjects

S Johansen

Publications and source records attributed to S Johansen.

At least 19 recordsLinked to original sources
PubMed2001

Inter- and intratester comparison of the Rolimeter knee tester: effect of tester's experience and the examination technique.

Clinical knee examination is imperative for the prognosis, follow-up, and scientific comparison of anterior cruciate ligament surgery results. A new device, the Rolimeter knee tester was studied in this study with respect to inter- and intratester reliability. We found no significant difference in the intratester evaluation, and data were reliable between repeated measurements and between different testers with the same examination technique. The tester's experience seems to play a role using use the Rolimeter knee tester, but even an inexperienced tester can use it and obtain data that are very close to the data obtained by an experienced tester when the same technique is used. Furthermore, it was found that the manual examination of anterior translation also provides a reliable measurement, at least in the hand of experienced testers. Further advantages are that the Rolimeter knee tester is cheap, can be sterilized, and is simple to use.

Adult↗
PubMed2000

[Pregnancy associated pelvic pain. I: Prevalence and risk factors].

With this study, we wanted to determine the incidence of symptom-giving pelvic girdle relaxation during pregnancy and the prevalence post partum, identify predisposing factors, and determine the frequency of sick leave. A total of 1600 pregnant women entered the study. The incidence during pregnancy was 14%, the prevalence two, six, and twelve months post partum was 5%, 4%, and 2%, respectively. Multivariate analysis indicated that the most important predisposing factor was pelvic pain in a previous pregnancy. Other factors were uncomfortable working conditions, lack of exercise, and previous low back and low abdominal pain. At least 37% of the women with symptom-giving pelvic girdle relaxation were on sick leave during pregnancy, on average for twelve weeks. Symptom-giving pelvic girdle relaxation is a considerable problem both in pregnancy and post partum. The occupational risk can possibly be prevented. The syndrome has a great social impact because of the high frequency of sick live.

Adult↗
PubMed2000

[Pregnancy associated pelvic pain. II: Symptoms and clinical findings].

Pelvic pain in pregnancy appears to be a problem on the increase. This study was undertaken to describe and analyse the relationship between subjective symptoms, daily disability, and clinical findings in women with symptom-giving pelvic girdle relaxation in pregnancy. Out of 1600 pregnant women, 238 had pelvic pain. After a clinical examination 11 women were excluded due to low back pain. The rest, 227 women, was considered to have symptom-giving pelvic girdle relaxation during pregnancy. Symptom-giving pelvic girdle relaxation in pregnancy seriously interferes with many activities of daily living such as housekeeping, walking, working, and sexual life. The women's statements of pelvic pain are well correlated to the number of positive clinical tests. Symptom-giving pelvic girdle relaxation in pregnancy causes considerable disabilities concerning daily activities.

Adult↗
PubMed2000

Flanking sequences with an essential role in hydrolysis of a self-cleaving group I-like ribozyme.

DiGIR1 is a group I-like ribozyme derived from the mobile twin ribozyme group I intron DiSSU1 in the nuclear ribosomal DNA of the myxomycete Didymium iridis. This ribozyme is responsible for intron RNA processing in vitro and in vivo at two internal sites close to the 5'-end of the intron endo-nuclease open reading frame and is a unique example of a group I ribozyme with an evolved biological function. DiGIR1 is the smallest functional group I ribozyme known from nature and has an unusual core organization including the 6 bp P15 pseudoknot. Here we report results of functional and structural analyses that identify RNA elements critical for hydrolysis outside the DiGIR1 ribozyme core moiety. Results from deletion analysis, disruption/compensation mutagenesis and RNA structure probing analysis all support the existence of two new segments, named P2 and P2.1, involved in the hydrolysis of DiGIR1. Significant decreases in the hydrolysis rate, k (obs), were observed in disruption mutants involving both segments. These effects were restored by compensatory base pairing mutants. The possible role of P2 is to tether the ribozyme core, whereas P2.1 appears to be more directly involved in catalysis.

Animals↗
PubMed2000

Expression of the Naegleria intron endonuclease is dependent on a functional group I self-cleaving ribozyme.

NaSSU1 is a complex nuclear group I intron found in several species of Naegleria, consisting of a large self-splicing group I ribozyme (NaGIR2), which itself is interrupted by a small, group I-like ribozyme (NaGIR1) and an open reading frame (ORF) coding for a homing endonuclease. The GIR1 ribozyme cleaves in vitro transcripts of NaSSU1 at two internal processing sites about 400 nt downstream of the 5' end of the intron, proximal to the endonuclease ORF. Here we demonstrate that self-cleavage of the excised intron also occurs in vivo in Naegleria gruberi, generating an ORF-containing RNA that possesses a short leader with a sequence element likely to be involved in gene expression. To assess the functional significance of self-cleavage, we constructed a genetic system in Saccharomyces cerevisiae. First, a mutant yeast strain was selected with a mutation in all the rRNA genes, rendering the rDNA resistant to cleavage by the Naegleria endonuclease. Active endonuclease, which is otherwise lethal, could be expressed readily in these cells. Endonuclease activity also could be detected in extracts of yeast harboring plasmids in which the endonuclease ORF was embedded in its native context in the intron. Analysis of the RNA from these yeast cells showed that the excised intron RNA was processed as in N. gruberi. A mutant intron constructed to prevent self-cleavage of the RNA failed to express endonuclease activity. These results support the hypothesis that the NaGIR1-catalyzed self-cleavage of the intron RNA is a key event in expression of the endonuclease.

Animals↗
PubMed2000

Orbital space-occupying lesions in Denmark 1974-1997.

PURPOSE: To determine the frequency, distribution according to diagnosis and the recurrence frequency of orbital space-occupying lesions in Denmark, to determine sex and age of the patients and to establish a national orbital data register. METHODS: All biopsied/surgically removed orbital lesions collected by Danish pathological departments during the period 1974-1997 were identified by SNOMED codes. In addition, in each case gender and age of the patients and number of recurrences were registered. RESULTS: 965 orbital lesions from 841 patients were identified during the 24-year period. The incidence of orbital lesions increased significantly over the study period and at present about 80 cases/year are registered. The ratio benign/malignant lesion per year remained constant during the observation period. Lesions in children constituted a total of 152 (16%), the percentage of lesions in children being constant during the period. Malignant tumors comprised a total of 364 (45%) in adults and 34 (22%) in children. Malignant tumors were in adults distributed with 43% primary, 48% secondary invading and 9% metastatic tumors, and in children with 65% primary, 29% secondary invading and 6% metastatic tumors. Normal tissue was only found in 6% of the cases recorded. CONCLUSION: A registration of all histologically evaluated orbital space-occupying lesions in Denmark during a period of 24 years was performed and a national orbital database established. Orbital lesions are rare and primarily benign.

Adolescent↗
PubMed2000

Functional characterization of isoschizomeric His-Cys box homing endonucleases from Naegleria.

Several species within the amoeboflagellate genus Naegleria harbor an optional ORF containing group I introns in their nuclear small subunit ribosomal DNA. The different ORFs encode homing endonucleases with 65 to 95% identity at the amino-acid level. I-NjaI, I-NanI and I-NitI, from introns in Naegleria jamiesoni, N. andersoni and N. italica, respectively, were analyzed in more detail and found to be isoschizomeric endonucleases that recognize and cleave an approximal 19-bp partially symmetrical sequence, creating a pentanucleotide 3' overhang upon cleavage. The optimal conditions for cleavage activity with respect to temperature, pH, salt and divalent metal ions were investigated. The optimal cleavage temperature for all three endonucleases was found to be 37 degrees C and the activity was dependent on the concentration of NaCl with an optimum at 200 mM. Divalent metal ions, primarily Mg2+, are essential for Naegleria endonuclease activity. Whereas both Mn2+ and Ca2+ could substitute for Mg2+, but with a slower cleavage rate, Zn2+ was unable to support cleavage. Interestingly, the pH dependence of DNA cleavage was found to vary significantly between the I-NitI and I-NjaI/I-NanI endonucleases with optimal pH values at 6.5 and 9, respectively. Site-directed mutagenesis of conserved I-NjaI residues strongly supports the hypothesis that Naegleria homing endonucleases share a similar zinc-binding structure and active site with the His-Cys box homing endonuclease I-PpoI.

Amino Acid Sequence↗
PubMed1999

In vivo expression of the nucleolar group I intron-encoded I-dirI homing endonuclease involves the removal of a spliceosomal intron.

The Didymium iridis DiSSU1 intron is located in the nuclear SSU rDNA and has an unusual twin-ribozyme organization. One of the ribozymes (DiGIR2) catalyses intron excision and exon ligation. The other ribozyme (DiGIR1), which along with the endonuclease-encoding I-DirI open reading frame (ORF) is inserted in DiGIR2, carries out hydrolysis at internal processing sites (IPS1 and IPS2) located at its 3' end. Examination of the in vivo expression of DiSSU1 shows that after excision, DiSSU1 is matured further into the I-DirI mRNA by internal DiGIR1-catalysed cleavage upstream of the ORF 5' end, as well as truncation and polyadenylation downstream of the ORF 3' end. A spliceosomal intron, the first to be reported within a group I intron and the rDNA, is removed before the I-DirI mRNA associates with the polysomes. Taken together, our results imply that DiSSU1 uses a unique combination of intron-supplied ribozyme activity and adaptation to the general RNA polymerase II pathway of mRNA expression to allow a protein to be produced from the RNA polymerase I-transcribed rDNA.

Amoeba↗
PubMed1999

Sequence Characterization of a Unique Intergenic Spacer in Gadiformes Mitochondrial DNA.

: The nucleotide sequences of intergenic spacers located between the tRNA(Thr) and tRNA(Pro) genes in mitochondrial DNA of cod fishes (order Godiformes) were determined. Spacers from eight species representing two families of cod fishes were analyzed and found to vary in size from 25 to 99 bp. Each spacer sequence contains one or two copies of a conserved 17-bp motif. Four to five central nucleotides of this motif constitute a substitutional hot spot as observed from interspecific and intraspecific comparisons. The substitution rate of the spacer is approximately twice that of the variable part I of the mitochondrial DNA control region, making this sequence region interesting as a molecular marker in population studies or stock assessments of cod fishes. We propose that the spacer originated in a duplication event and evolved into a functional domain, perhaps by binding regulatory proteins.

Journal Article↗
PubMed1999

Complex group-I introns in nuclear SSU rDNA of red and green algae: evidence of homing-endonuclease pseudogenes in the Bangiophyceae.

The green alga Scenedesmus pupukensis and the red alga Porphyra spiralis contain large group-IC1 introns in their nuclear small subunit ribosomal RNA genes due to the presence of open reading frames at the 5' end of the introns. The putative 555 amino-acid Scenedesmus-encoded protein harbors a sequence motif resembling the bacterial S9 ribosomal proteins. The Porphyra intron self-splices in vitro, and generates both ligated exons and a full-length intron RNA circle. The Porphyra intron has an unusual structural organization by encoding a potential 149 amino-acid homing-endonuclease-like protein on the complementary strand. A comparison between related group-I introns in the Bangiophyceae revealed homing-endonuclease-like pseudogenes due to frame-shifts and deletions in Porphyra and Bangia. The Scenedesmus and Porphyra introns provide new insights into the evolution and possible novel functions of nuclear group-I intron proteins.

Amino Acid Motifs↗
PubMed1999

I-NjaI, a nuclear intron-encoded homing endonuclease from Naegleria, generates a pentanucleotide 3' cleavage-overhang within a 19 base-pair partially symmetric DNA recognition site.

Different species of the amoebo-flagellate Naegleria harbor optional group I introns in the nuclear ribosomal DNA that contain open reading frames. Intron proteins from Naegleria jamiesoni, Naegleria andersoni, and Naegleria italica (named I-NjaI, I-NanI and I-NitI, respectively) were expressed in Escherichia coli and found to be isoschizomeric homing endonucleases that specifically recognize and cleave intron-lacking homologous alleles of ribosomal DNA. The I-NjaI endonuclease was affinity purified, characterized in more detail, and found to generate five-nucleotide 3' staggered ends at the intron insertion site which differs from the ends generated by all other known homing endonucleases. The recognition site was delimited and found to cover an approximately 19 base-pair partially symmetric sequence spanning both the cleavage site and the intron insertion site. The palindromic feature was supported by mutational analysis of the target DNA. All single-site substitutions within the recognition sequence were cleaved by the purified I-NjaI endonuclease, but at different efficiencies. The center of symmetry and cleavage was found to be completely degenerate in specificity, which resembles that of the subclass IIW bacterial restriction enzymes.

Amino Acid Sequence↗
PubMed1999

Structural characteristics and possible horizontal transfer of group I introns between closely related plant pathogenic fungi.

We have characterized structural features and the distribution pattern of nuclear group I introns found in ribosomal DNA (rDNA) of closely related plant pathogenic fungi of the family Sclerotiniaceae. Sixteen introns, at two distinct positions in the small-subunit (SSU) and large-subunit (LSU) rDNA, were sequenced and analyzed among the 29 taxa included in the initial screening. Genera found to contain introns were Botrytis, Dumontinia, Encoelia, Grovesinia, Myriosclerotinia, and Sclerotinia. Secondary-structure analyses of the group I introns concluded that all belong to the common IC1 subclass. Interestingly, the SSU rDNA intron from Myriosclerotinia caricisampullacea contains an insertion-like sequence extension which may be a relic of an open reading frame. Incongruent branching patterns of intron-based and rDNA-based (internal transcribed spacer) phylogenetic trees suggest that the fungal host genomes and the group I introns do not share a common evolutionary history. A model to explain how horizontal intron transfers may have occurred among the closely related fungal taxa is proposed.

Amino Acid Sequence↗
PubMed1999

Symptom-giving pelvic girdle relaxation in pregnancy. I: Prevalence and risk factors.

BACKGROUND: Previous studies concerning symptom-giving pelvic girdle relaxation in pregnancy have to our knowledge been retrospective. We wanted to 1) determine the incidence during pregnancy and the prevalence two, six, and twelve months post partum, 2) identify possible predisposing factors, and 3) determine the frequency and duration of sicklisting, prospectively. MATERIAL AND METHODS: A cohort of 1600 consecutive pregnant women filled in a questionnaire. At the routine prenatal examinations they were asked about pelvic pain. Those who fulfilled the inclusion criteria were examined by a rheumatologist to confirm the diagnosis. The affected women were seen again two, six, and twelve months post partum. All participants were asked about sicklisting in pregnancy. RESULTS: The incidence during pregnancy was 14%, the prevalence two, six, and twelve months post partum were 5%, 4%, and 2% respectively. Multivariate analysis indicates that the most important predisposing factor is pelvic pain in a previous pregnancy. Other factors were uncomfortable working conditions, lack of exercise, and previous low back pain and low abdominal pain. At least 37% of the women with symptom-giving pelvic girdle relaxation had been sicklisted in pregnancy due to pelvic pain, on average for twelve weeks. CONCLUSION: Symptom-giving pelvic girdle relaxation is a considerable problem both in pregnancy and post partum. The occupational risk can possibly be prevented. The syndrome has a great social impact because of the frequent sicklisting.

Adult↗
PubMed1999

Symptom-giving pelvic girdle relaxation in pregnancy. II: Symptoms and clinical signs.

BACKGROUND: Pelvic pain in pregnancy appears to be a problem that is increasing. This study was undertaken to describe and analyze the relationship between subjective symptoms, daily disability, and clinical findings in women with symptom-giving pelvic girdle relaxation in pregnancy MATERIALS AND METHODS: Out of 1600 pregnant women 238 had pelvic pain. After a clinical examination 11 women were excluded due to low back pain. The rest, 227 women, was considered having symptom-giving pelvic girdle relaxation during pregnancy. RESULTS: Symptom-giving pelvic girdle relaxation in pregnancy seriously interferes with many activities of daily living such as housekeeping, walking, working, and sexual life. The women's statements of pelvic pain are well correlated to the number of positive clinical tests. CONCLUSION: Symptom-giving pelvic girdle relaxation in pregnancy causes considerable disabilities concerning daily activities.

Activities of Daily Living↗
PubMed1998

Group I twintrons: genetic elements in myxomycete and schizopyrenid amoeboflagellate ribosomal DNAs.

Protists are unicellular eukaryotes which represent a significant fraction of the global biodiversity. The myxomycete Didymium and the schizopyrenid amoeboflagellate Naegleria are distantly related protists. However, we have noted several striking similarities in life cycle, cell morphology, and ribosomal DNA organization between these organisms. Both have multicopy nuclear extrachromosomal ribosomal DNAs. Here the small subunit ribosomal RNA genes are interrupted by an optional group I twintron, a novel category among the group I introns. Group I twintrons are mobile self-splicing introns of 1.3-1.4 kb in size, with a complex organization at the RNA level. A group I twintron consists of two distinct ribozymes (catalytic RNAs) with different functions in RNA processing, and an open reading frame encoding a functional homing endonuclease--all with prospects of application as molecular tools in biotechnology. Updated RNA secondary structure models of group I twintrons, as well as an example of in vitro ribozyme activity, are presented. We suggest that the group I twintrons have been independently established in myxomycetes and schizopyrenid amoeboflagellates by horizontal gene transfer due to a combination of the phagocytotic behavior in natural environments and the extrachromosomal multicopy nature of ribosomal DNA.

Animals↗
PubMed1998

Junctioning of lateral and anterior fields in head and neck cancer: a dosimetric assessment of the monoisocentric technique (including reproducibility).

PURPOSE: The matching or junctioning of two lateral fields with an anterior field is commonly performed in the treatment of head and neck cancer. A monoisocentric technique utilising asymmetric collimation is potentially associated with improved dosimetry in the plane of the junction due to decreased reliance on operator skill and the avoidance of couch movement. The aim of this study was not only to assess the average dose delivered in the plane of the junction, but also the reproducibility of this dose for the monoisocentric technique and two other commonly used techniques. METHODS AND MATERIALS: An anthropomorphic head and neck wax phantom was fashioned to allow the placement of 22 TLD chips in a 2-mm thick transverse plane positioned superior to the potential site of the larynx. Three different treatment techniques were used with the phantom being treated by four different operators a minimum of 20 times for each technique: (1) "straight fields"--using isocentric laterals with an anterior field junctioned in the midline. This technique makes no allowance for divergence; (2) "angled fields"--couch and gantry rotation are used to account for divergence; (3) "monoisocentric"--using asymmetric collimators to create a single isocenter. RESULTS: For an applied dose of 1 Gy the monoisocentric technique produced a mean dose measured of 1.01 Gy compared with 1.23 and 0.92 Gy for techniques 1 and 2. The reproducibility of the mean dose measured was better for the monoisocentric technique by a factor of 2. The superior reproducibility of the monoisocentric technique was not found to be operator dependent. CONCLUSIONS: A monoisocentric technique for the treatment of two laterals and an anterior field in head and neck cancer is likely to be associated with more accurate and reproducible dosimetry in the plane of the junction. Our center has subsequently adopted this technique for matching such fields.

Head and Neck Neoplasms↗