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Biomedical subjects

S Kristjansson

Publications and source records attributed to S Kristjansson.

8 recordsLinked to original sources
PubMed2002

Stability of questionnaire items measuring behaviours, attitudes and stages of change related to sun exposure.

The use of questionnaires in epidemiological studies needs more methodological research. The time and effort spent on questionnaire design is often limited. Studies on the construction of questionnaires could lead to a higher quality of data, enhanced comparability and improved credibility of epidemiological findings. The aim of the present study was to examine the test-retest reliability of some common items measuring sun-related variables. A sample of 52 female Swedish nurses attending a postgraduate course in research methodology was chosen. They completed a questionnaire on two occasions spaced 3 weeks apart in the winter of 2000. When the results were analysed, items on sun-related behaviours and sunbed use were sufficiently reliable. The items on skin type and sunburn showed moderate stability. Stage of change related to sunlight exposure, items measuring beliefs about sunbathing along with items assessing self-efficacy and risk perception with regards to sunbathing showed lower stability. The results showed that many essential items concerning exposure to ultraviolet radiation and sunburns were sufficiently stable, but other items were less stable and could be improved upon; suggestions for improving these items are presented. The study illustrates the value of reliability testing in the process of item construction. Using methodological studies to improve the reliability and validity of data is an important step toward higher standards for questionnaire surveys.

Adult↗
PubMed2001

Tanning habits and sunburn in a Swedish population age 13-50 years.

As part of a skin cancer control programme, we studied the occurrence of self-reported outdoor tanning, sunbed use and ultraviolet (UV)-induced erythema in an urban area. A cross-sectional questionnaire study of 6000 adolescents aged 13-19 years, and 4000 adults aged 20-50 years was applied. Non-response was analysed for outdoor tanning and sunbed use. Results, in general, did not differ between responders and non-responders. Females aged 17-29 years tanned outdoors most frequently. Sunbed use and related erythema was twice as common in young females. In males, outdoor tanning was not age-related. In the past 12 months, 55% reported sunburn and/or burn from sunbed use, one-third were burned in Sweden, one-quarter on sunny resorts abroad. Sunburn occurs frequently. Compliance with recommendations for sunbed use is poor, especially among adolescents and young adults. To reduce the occurrence of erythema, the influence of risk settings upon behaviours is a critical issue for exploration.

Adolescent↗
PubMed2001

Analysis of 76Br-BrdU in DNA of brain tumors after a PET study does not support its use as a proliferation marker.

76Br-bromodeoxyuridine has previously been suggested as a PET tracer to characterize proliferation potential. However, in animal studies a large fraction of the tissue radioactivity is due to 76Br-bromide, which remains extracellular for extensive periods and contributes significantly to the level of radioactivity. The present project aimed at investigating whether in human brain tumors, sufficient amounts of 76Br-bromodeoxyuridine would be incorporated into DNA, to motivate further attempts with this tracer. Eight patients with brain tumors: 3 meningiomas, 2 astrocytoma grade IV, 1 astrocytoma oligodendroglioma grade II-IV and 2 metastases, were examined with PET and 76Br-BrdU on three occasions: immediately after injection of the tracer, at 4-6, and at 18-20 hours after administration. After the first PET study, diuresis was introduced and maintained for about 12 hours. About 20 hours after tracer administration, 200 mg/m(2) bromodeoxyuridine was administered to 7 patients median 5.8 (range 1-22) hours prior to operation allowing the immunohistochemical analysis of the proliferation potential. During the operation, tumor samples were taken and radioactivity in DNA extracted and measured. The uptake of radioactivity was higher in the tumors than in brain parenchyma. However, in the operative samples only 1-27% (average: 9%) of the radioactivity was found in the DNA fraction. The plasma radioactivity remained high throughout the study with only minimal signs of elimination by the diuresis. 76Br-BrdU is extensively metabolized to 76Br-bromide, and only a minor fraction of the radioactivity is found in the DNA fraction, making it unlikely that this tracer can be used for assessment of proliferation potential.

Aged↗
PubMed1995

Horizontal plane morphometry of normal and scoliotic vertebrae. A methodological study.

Computed tomography (CT) scans are widely used for quantification of the morphology of the vertebral body and of the changes of the thoracic cage in the horizontal plane in scoliosis. So far, however, no method exists for precise quantification of the parameters of the posterior elements. We present a method for quantification on the basis of CT scans of different parameters of the morphology of both the vertebral body and posterior elements in the horizontal plane. The precision and accuracy of the method were estimated in a model study by CT scanning of a normal and a scoliotic vertebra in different, controlled, tilted positions. Moreover, in a clinical study CT scans of 19 thoracic vertebrae from non-scoliotic subjects and the apex vertebra from 40 scoliotic subjects were selected to test the applicability of the method to clinical studies. The intra- and interobserver variation of the measurements was analysed. The angle between the longitudinal axis of the vertebral body and that of the whole vertebra was used to evaluate the asymmetry of the vertebral body. The right to left pedicle width index, the right to left hemi-canal width index and the index of transverse process angles related to the axis of the vertebra were used to quantify the asymmetry of the posterior elements. The results indicate that, except for the pedicle width index, the variables under study were not significantly influenced by a 5 degrees or 10 degrees tilt ventrally, dorsally, or laterally of either the normal or the scoliotic vertebra. Hence, the method can be satisfactorily applied to longitudinal group comparisons.(ABSTRACT TRUNCATED AT 250 WORDS)

Anthropometry↗
PubMed1995

Electrical muscle stimulation on the spine. Three-dimensional effects in rabbits.

We investigated the 3-dimensional effect of electrostimulation of the latissimus dorsi, the erector spinae and the intercostal muscles on spinal configuration in 16 New Zealand white rabbits. Electrostimulation on the right side of the spine resulted in a left convex, hypokyphotic curve and vertebral body rotation towards the convexity of the curve in all rabbits. The Cobb angle in the coronal plane increased with stimulation of each of the muscles examined. The kyphosis decreased with stimulation of the latissimus dorsi and the erector spinae. The vertebral rotation increased with stimulation of all muscles. Stimulation of the tested muscles resulted in the simultaneous occurrence of a 3-dimensional spinal deformity with the characteristics of idiopathic scoliosis.

Animals↗
PubMed1995

Creatine supplementation in chronic heart failure increases skeletal muscle creatine phosphate and muscle performance.

BACKGROUND: Cardiac creatine levels are depressed in chronic heart failure. Oral supplementation of creatine to healthy volunteers has been shown to increase physical performance. AIM: To evaluate the effects of creatine supplementation on ejection fraction, symptom-limited physical endurance and skeletal muscle strength in patients with chronic heart failure. METHODS: With a double-blind, placebo-controlled design 17 patients (age 43-70 years, ejection fraction < 40) were supplemented with creatine 20 g daily for 10 days. Before and on the last day of supplementation ejection fraction was determined by radionuclide angiography as was symptom-limited 1-legged knee extensor and 2-legged exercise performance on the cycle ergometer. Muscle strength as unilateral concentric knee extensor performance (peak torque, Nm at 180 degrees/s) was also evaluated. Skeletal muscle biopsies were taken for the determination of energy-rich phosphagens. RESULTS: Ejection fraction at rest and at work did not change. Performance before creatine supplementation did not differ between placebo and creatine groups. While no change was seen in the placebo group compared to baseline, creatine supplementation increased skeletal muscle total creatine and creatine phosphate by 17 +/- 4% (P < 0.05) and 12 +/- 4% (P < 0.05), respectively. Increments were seen only in patients with < 140 mmol total creatine/kg d.w. (P < 0.05). One-legged performance (21%, P < 0.05), 2-legged performance (10%, P < 0.05), and peak torque, Nm (5%, P < 0.05) increased. Both peak torque and 1-legged performance increased linearly with increased skeletal muscle phosphocreatine (P < 0.05). The increments in 1-legged, 2-legged and peak torque were significant compared to the placebo group, (P < 0.05). CONCLUSIONS: One week of creatine supplementation to patients with chronic heart failure did not increase ejection fraction but increased skeletal muscle energy-rich phosphagens and performance as regards both strength and endurance. This new therapeutic approach merits further attention.

Administration, Oral↗
PubMed1994

Leukotriene B4 and C4 generation by blood leukocytes after ex vivo stimulation by Ca-ionophore and opsonized zymosan in children with atopic dermatitis.

The ex vivo release of leukotrienes B4 (LTB4) and C4 (LTC4) from the leukocytes of children with atopic dermatitis (AD) was evaluated after stimulation with Ca-ionophore and opsonized zymosan and compared with that of control children of similar ages. The blood eosinophil counts and total serum IgE levels in AD children were significantly higher than those in control children. The production of LTC4, but not LTB4, was significantly higher in AD children than in control children. There was a significant correlation between the relative blood eosinophil count and LTC4 generation after stimulation with both Ca-ionophore and opsonized zymosan in all subjects. Calculations of the amount of LTC4 produced per eosinophilic cell showed that there was no significant difference between cells from AD children and control children in terms of their ability to produce LTC4. These findings suggest that the enhanced LTC4 generation is due to increased numbers of eosinophils rather than to enhanced releasability of these cells.

Adolescent↗