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Stian Lydersen

Publications and source records attributed to Stian Lydersen.

At least 19 recordsLinked to original sources
PubMed2026

Effects of Intravenously Administered Plasma from Exercise-Trained Donors on Mitochondrial Respiration in a Rat Model of Alzheimer's Disease.

PURPOSE: Dysfunction of mitochondria is observed early in Alzheimer's disease (AD), possibly driving the pathogenesis of the disease. This study aims to assess whether plasma from exercise-trained donors can enhance mitochondrial function in a transgenic AD model and to gain insight into the proteomic profile of the donor plasma. METHODS: Male McGill-R-Thy1-APP rats (n = 3 per treatment group) were treated at either an early preplaque stage (2.2 months) or a later stage (5.2 months) with plasma from exercise-trained donors (ExPlas), sedentary donors (SedPlas), or saline. The rats received 14 transfusions over 6&#x2009;wk. Mitochondrial respiration was assessed in cornu ammonis (CA), dentate gyrus (DG), gastrocnemius, and left ventricle using high-resolution respirometry. Proteomic analyses were performed in donor blood using mass spectrometry. RESULTS: In early-stage AD rats, ExPlas improved hippocampal mitochondrial respiration. Compared with saline, CA oxidative phosphorylation (OXPHOS) capacity for complex I increased by +30.8 pmol O2&#xb7;s-1&#xb7;mg-1 (P < 0.001) and CI+II by +37.8 pmol O2&#xb7;s-1&#xb7;mg-1 (P < 0.001). Compared with SedPlas, CA OXPHOS for CI increased by +16.9 pmol O2&#xb7;s-1&#xb7;mg-1 (P = 0.01) and CI+II by +23.8 pmol O2&#xb7;s-1&#xb7;mg-1 (P = 0.007). In DG, similar improvements were only seen compared with saline. In CA, but not DG, of later-stage rats, ExPlas produced smaller but significant increases in CI and CI+II OXPHOS compared with saline, but no significant differences compared with SedPlas. No changes were observed in muscle or heart. Proteomics revealed enrichment of complement and platelet-related pathways in ExPlas. CONCLUSIONS: This proof-of-concept study shows that exercise-trained donor plasma enhances hippocampal mitochondrial respiration in early-stage AD rats and, to a lesser extent, in later-stage AD rats. The proteomic profile of the exercise-trained donor plasma indicates a role of altered complement and platelet functions.

Animals↗
PubMed2006

GeneTools--application for functional annotation and statistical hypothesis testing.

BACKGROUND: Modern biology has shifted from "one gene" approaches to methods for genomic-scale analysis like microarray technology, which allow simultaneous measurement of thousands of genes. This has created a need for tools facilitating interpretation of biological data in "batch" mode. However, such tools often leave the investigator with large volumes of apparently unorganized information. To meet this interpretation challenge, gene-set, or cluster testing has become a popular analytical tool. Many gene-set testing methods and software packages are now available, most of which use a variety of statistical tests to assess the genes in a set for biological information. However, the field is still evolving, and there is a great need for "integrated" solutions. RESULTS: GeneTools is a web-service providing access to a database that brings together information from a broad range of resources. The annotation data are updated weekly, guaranteeing that users get data most recently available. Data submitted by the user are stored in the database, where it can easily be updated, shared between users and exported in various formats. GeneTools provides three different tools: i) NMC Annotation Tool, which offers annotations from several databases like UniGene, Entrez Gene, SwissProt and GeneOntology, in both single- and batch search mode. ii) GO Annotator Tool, where users can add new gene ontology (GO) annotations to genes of interest. These user defined GO annotations can be used in further analysis or exported for public distribution. iii) eGOn, a tool for visualization and statistical hypothesis testing of GO category representation. As the first GO tool, eGOn supports hypothesis testing for three different situations (master-target situation, mutually exclusive target-target situation and intersecting target-target situation). An important additional function is an evidence-code filter that allows users, to select the GO annotations for the analysis. CONCLUSION: GeneTools is the first "all in one" annotation tool, providing users with a rapid extraction of highly relevant gene annotation data for e.g. thousands of genes or clones at once. It allows a user to define and archive new GO annotations and it supports hypothesis testing related to GO category representations. GeneTools is freely available through www.genetools.no

Algorithms↗
PubMed2006

Prevalence of haemochromatosis gene mutations in Parkinson's disease.

The aim of this study was to investigate a possible association between haemochromatosis (HFE) gene mutations and the prevalence of Parkinson's disease. The HFE gene encodes a protein that modulates iron absorption. Several studies have documented increased iron levels in the basal ganglia in patients with Parkinson's disease. In a study on patients with concurrent hereditary haemochromatosis and Parkinson's disease, abnormal deposition of iron in the basal ganglia was suggested as an inductor of Parkinson's disease. In this study, genotype frequencies of the HFE mutations C282Y, H63D and S65C were estimated in 388 patients with Parkinson's disease and compared with frequencies found in comparable studies. No significant differences were found in frequencies between the patients and comparable populations. This study does not indicate increased susceptibility to Parkinson's disease in HFE gene mutation carriers in Norway.

Basal Ganglia↗
PubMed2006

International comparison of the relationship of chronic kidney disease prevalence and ESRD risk.

ESRD incidence is much lower in Europe compared with the United States. This study investigated whether this reflects a difference in the prevalence of earlier stages of chronic kidney disease (CKD) or other mechanisms. CKD prevalence in Norway was estimated from the population-based Health Survey of Nord-Trondelag County (HUNT II), which included 65,181 adults in 1995 through 1997 (participation rate 70.4%). Data were analyzed using the same methods as two US National Health and Nutrition Examination Surveys in 1988 through 1994 (n = 15,488) and 1999 through 2000 (n = 4101). The primary analysis used gender-specific cutoffs in estimating persistent albuminuria for CKD stages 1 and 2. ESRD rates and other relevant data were extracted from national registries. Total CKD prevalence in Norway was 10.2% (SE 0.5): CKD stage 1 (GFR >90 ml/min per 1.73 m2 and albuminuria), 2.7% (SE 0.3); stage 2 (GFR 60 to 89 ml/min per 1.73 m2 and albuminuria), 3.2% (SE 0.4); stage 3 (GFR 30 to 59 ml/min per 1.73 m2), 4.2% (SE 0.1); and stage 4 (GFR 15 to 29 ml/min per 1.73 m2), 0.2% (SE 0.01). This closely approximates reported US CKD prevalence (11.0% in 1988 through 1994 and 11.7% in 1999 through 2000). The relative risk for progression from CKD stages 3 or 4 to ESRD in US white patients compared with Norwegian patients was 2.5. This was only modestly modified by adjustment for age, gender, and diabetes. Age and GFR at start of dialysis were similar, hypertension and cardiovascular mortality in the populations were comparable, but US white patients were referred later to a nephrologist and had higher prevalence of obesity and diabetes. In conclusion, CKD prevalence in Norway was similar to that in the United States, suggesting that lower progression to ESRD rather than a smaller pool of individuals at risk accounts for the lower incidence of ESRD in Norway.

Age Distribution↗
PubMed2006

Estimating glomerular filtration rate in the general population: the second Health Survey of Nord-Trondelag (HUNT II).

BACKGROUND: Guidelines recommend the modification of diet in the renal disease (MDRD) formula or the Cockcroft-Gault formula for estimating the glomerular filtration rate (GFR). However, there is an ongoing discussion whether the MDRD formula should be used in the general population as several studies have found a large underestimation of its GFR estimates. METHODS: In this study, 1,029 low-risk subjects, eligible for kidney donation according to internationally accepted criteria were selected from the population-based second Health Survey of Nord-Trondelag (HUNT II). Serum creatinine values traceable to isotope dilution mass spectrometry were used with the re-expressed MDRD formula recently published. The 2.5th, 50th and 97.5th percentiles of GFR by age were calculated and compared to reference values from the literature, which are based on GFR measured with gold standard methods in potential kidney donors. RESULTS: The difference between the 50th percentiles for MDRD estimates and measured GFR in the literature was small and constant over age: +0.5 ml/min/1.73 m(2) at age 20 and -2.0 ml/min/1.73 m(2) at age 80. Bias for Cockcroft-Gault estimates varied from 0.0 ml/min/1.73 m(2) to -21.4 ml/min/1.73 m(2). Other formulae also had a too steep age correction, and bias among the elderly varied from -10 to -30 ml/min/1.73 m(2). Hence, 30-80% of the general population above age 60 had GFR estimates below their age-specific 2.5th percentile of normal kidney function, while the MDRD formula was much more conservative (13.3%). CONCLUSION: The MDRD formula gave nearly unbiased estimates for normal GFR. All other formulae tested had, especially in the elderly, a much larger negative bias and cannot be recommended for use in the general population.

Adult↗
PubMed2006

[Use of estrogen replacement therapy and alternative therapies among Norwegian women aged 50-69].

BACKGROUND: Several large studies have showed higher risk and less benefit from hormone replacement therapy (HRT) than assumed, and sales figures have been reduced by almost a half. Several non-hormonal treatment alternatives for climacteric complaints are available. The object of this study was to determine the occurrence of climacteric complaints, and to study the use and efficacy of hormonal and alternative therapies among Norwegian women. MATERIAL AND METHODS: 150 participants in the Norwegian Mammography Screening Programme in Trondheim were interviewed about climacteric symptoms, use of HRT, and of alternative therapies. RESULTS: 81% of the participants had experienced vasomotor symptoms. The prevalence was highest among women aged 55-59 years. 23% of the women were current users of HRT, 27% were past users. 75% of the HRT users reported good effect. 25% of the participants were current users of alternative therapies, while 17% were past users. Soy was most frequently used as an alternative therapy. 42% of the alternative therapies were reported to be effective. INTERPRETATION: Half of the participants had used HRT, and most of these reported good effect. A corresponding number of women had used various alternative therapies, but the perceived efficacy of these was significantly poorer.

Climacteric↗
PubMed2006

Factors affecting stiffness properties in impacted morsellized bone used in revision hip surgery: an experimental in vitro study.

When revising loosened joint prosthesis, impacted morsellized bone is frequently used as organic scaffolding. We studied the relative influence that different bone particle size, impaction energy, and liquid content had on impacted bone stiffness. Bovine bone was morsellized in a bone mill by three grinding drums to produce bone with different chip size distribution. Next, portions of bone chips of controlled sizes were produced by a five-leveled sieve. Layer by layer of bone are constructed into pellets by our experimental impaction method. This method allows us to vary one independent factor at a time in a controlled manner while keeping the other factors constant. Stiffness for all bone pellets were measured during impaction and loading. In earlier studies, we focused on how impaction force, number of impaction strokes, and bone liquid contents influence mechanical behavior. Here, we compare the outcome of all studies using general linear models. All five factors significantly contribute to stiffness of impacted morsellized bone. Changing bone moisture has major, while increasing the number of impaction strokes beyond five per layer has minor effect. Low water content is the main contributor to highest load stiffness. Optimal stability of impacted morsellized bone is achieved with dried and well-graded particles. The number of heavy impaction strokes can be restricted.

Animals↗
PubMed2006

Prevalence, comorbidity and impact of irritable bowel syndrome in Norway.

OBJECTIVE: To study the prevalence of irritable bowel syndrome (IBS) and its comorbidity in a Norwegian adult population. MATERIAL AND METHODS: In 2001, 11,078 inhabitants (aged 30-75 years) in Oppland County were invited to take part in a public health survey. A total of 4622 subjects (42%) completed the questionnaires on symptoms of IBS (Rome II criteria), comorbidity, health-care visits and medications. The impact of comorbidity on global health, working disability and use of health-care resources in subjects with IBS was explored by stepwise logistic regression. RESULTS: The population prevalence of IBS was 388/4622 (8.4% (95% CI: 7.6-9.4%)) with a female predominance and an age-dependent decrease. The proportion who had consulted for IBS ranged from 51% among 30-year-olds to 79% in 75-year-olds (p=0.05). IBS was associated with musculoskeletal complaints (OR = 2.4-3.4 for six different items), fibromyalgia (OR = 3.6 [2.7-4.8]), mood disorder (OR = 3.3 (2.6-4.3)), reduced global health (OR = 2.6 (2.1-3.2)), working disability (OR = 1.6 (1.2-2.1)), more frequent health-care visits and use of medications (OR 1.7-2.3). When controlling for comorbidity, reduced global health (OR = 1.5 (1.1-2.0)) and use of alternative health care (OR = 1.7 (1.3-2.4)) remained associated with IBS. Severity of abdominal pain/discomfort was a predictor of having to seek a physician for IBS (OR = 1.3 (1.2-1.5)). CONCLUSIONS: Symptoms of IBS were reported by 8% of Norwegian adults and had resulted in consultations with physicians for the majority in the long run. Subjects with IBS in the community were characterized by frequent somatic and psychiatric comorbidity. Their observed reduced health, working disability and increased use of health resources were largely explained by comorbid symptoms and disorders.

Adult↗
PubMed2006

Digestive symptoms and their psychosocial impact: validation of a questionnaire.

OBJECTIVE: Questionnaires evaluating digestive symptoms and their psychosocial impact have not been extensively validated in Norwegian populations. In this study a self-administered questionnaire developed in Norway is evaluated for this purpose. MATERIAL AND METHODS: The questionnaire, the Digestive Symptoms and Impact Questionnaire, DSIQ, was developed by a cooperative group of general practitioners and gastroenterologists. The DSIQ contains 18 similarly structured global-type questions focusing on the patient's own judgement. The validation was based on 567 patients with dyspeptic symptoms or reflux symptoms referred to gastroscopy from general practice. RESULTS: Eighty percent of the patients responded to all the questions. All response categories were used for all questions. Factor analysis revealed 4 subscales: abdominal pain and bowel symptoms; gastric dysfunction; health impairment and impairment of everyday life. A question about reflux symptoms was retained as a subscale on its own. Overall score was established by calculating the mean of all question responses. Test-retest reliability in stable patients (intraclass correlation coefficient, range 0.80- 0.91) and internal consistency reliability (Cronbach's alpha, range 0.65-0.91) were satisfactory. Criterion validity was supported by significant correlations to patients' globally estimated quality of life and the General Health Questionnaire (GHQ-30). Responsiveness in spontaneously improved patients or patients given effective treatment ranged from moderate to highly responsive (responsiveness statistic range from 0.54 to 2.83). CONCLUSIONS: The DSIQ is a self-administered, simple and well-validated method for evaluating digestive symptoms and their psychosocial impact. The DSIQ shows satisfactory internal consistency reliability, test-retest reliability, responsiveness and criterion validity.

Adult↗
PubMed2006

Health-related quality of life three years after coronary surgery: a comparison with the general population.

OBJECTIVES: To assess health-related quality of life (HRQOL) in patients three years after coronary artery bypass grafting (CABG) compared to the general Norwegian population, with emphasis on age and gender-differences. DESIGN: A cross-sectional postal survey of patients who underwent CABG in 2000. HRQOL was assessed using the Short Form 36 (SF-36). Subgroup analyses were performed according to age (<70 versus =70 years) and gender. RESULTS: Of 233 eligible patients 203 responded (mean age 67.6 years, 17% females). Patients reported better scores on bodily pain than the general population (p=0.008), but did not differ on other subscales of SF-36. Younger patients tended to score lower, older patients higher than the general population on HRQOL. Female patients reported lower HRQOL than the general female population and reported significantly lower scores than male patients on 3 of 8 subscales. CONCLUSIONS: Three years after CABG the HRQOL is comparable to the general Norwegian population even in older patients. The older patients reported less pain than the general population.

Age Factors↗
PubMed2006

Effects of n-3 fatty acids in subjects with type 2 diabetes: reduction of insulin sensitivity and time-dependent alteration from carbohydrate to fat oxidation.

BACKGROUND: Effects of fish oil supplements on metabolic variables are insufficiently clarified in type 2 diabetes. OBJECTIVE: We aimed to investigate short-term (1 wk) and longer-term (9 wk) effects of n-3 fatty acids. DESIGN: Twenty-six subjects with type 2 diabetes without hypertriacylglycerolemia participated in a double-blind controlled study. Median intake in the intervention group was 17.6 mL fish oil/d (1.8 g 20:5n-3, 3.0 g 22:6n-3, and 5.9 g total n-3 fatty acids). The control group received 17.8 mL corn oil/d (8.5 g 18:2n-6). RESULTS: Plasma phospholipid 20:5n-3 and 22:6n-3 increased, whereas 18:2n-6 decreased, in the fish oil group compared with the corn oil group after 1 wk. The two n-3 fatty acids also increased in adipose tissue biopsy samples taken after 9 wk in the fish oil group. Glucose concentrations (home-monitored) were approximately 1 mmol/L higher in the fish oil group than in the corn oil group at the end of the intervention (P = 0.035). Glucose utilization measured by using an isoglycemic clamp was lowered in the fish oil group compared with that in the corn oil group at the end of the intervention (P = 0.049), whereas glucagon-stimulated C-peptide tended to increase (P = 0.078). The fish oil group utilized less fat for oxidation after 1 wk, with a change to more fat and less carbohydrate oxidation after 9 wk (P = 0.040), than did the corn oil group. CONCLUSION: A high intake of fish oil moderately increases blood glucose and decreases insulin sensitivity in persons with type 2 diabetes without hypertriacylglycerolemia and alters carbohydrate and fat utilization in a time-dependent manner.

Adult↗
PubMed2006

Cost effectiveness of a smoking cessation program in patients admitted for coronary heart disease.

BACKGROUND: Smoking cessation is probably the most important action to reduce mortality after a coronary event. Smoking cessation programs are not widely implemented in patients with coronary heart disease, however, possibly because they are thought not to be worth their costs. Our objectives were to estimate the cost effectiveness of a smoking cessation program, and to compare it with other treatment modalities in cardiovascular medicine. METHODS: A cost-effectiveness analysis was performed on the basis of a recently conducted randomized smoking cessation intervention trial in patients admitted for coronary heart disease. The cost per life year gained by the smoking cessation program was derived from the resources necessary to implement the program, the number needed to treat to get one additional quitter from the program, and the years of life gained if quitting smoking. The cost effectiveness was estimated in a low-risk group (i.e. patients with stable coronary heart disease) and a high-risk group (i.e. patients after myocardial infarction or unstable angina), using survival data from previously published investigations, and with life-time extrapolation of the survival curves by survival function modeling. RESULTS: In a lifetime perspective, the incremental cost per year of life gained by the smoking cessation program was euro 280 and euro 110 in the low and high-risk group, respectively (2000 prices). These costs compare favorably to other treatment modalities in patients with coronary heart disease, being approximately 1/25 the cost of both statins in the low-risk group and angiotensin-converting enzyme inhibitors in the high-risk group. In a sensitivity analysis, the costs remained low in a wide range of assumptions. CONCLUSIONS: A nurse-led smoking cessation program with several months of intervention is very cost-effective compared with other treatment modalities in patients with coronary heart disease.

Adult↗
PubMed2006

Increased fibrinolysis and platelet activation in elderly patients undergoing coronary bypass surgery.

Reexploration for hemorrhage after cardiac surgery is associated with increased morbidity and mortality. Elderly cardiac surgical patients have an increased risk of excessive bleeding and reexploration. In the present study we investigated the perioperative hemostatic function in elderly patients compared with younger patients undergoing coronary artery bypass grafting. Twenty-five elderly (75 yr and older) and 25 younger (younger than 60 yr) patients were included in the study. Blood samples for the analysis of platelet counts, international normalized ratio, activated partial thromboplastin time, fibrinogen, d-dimer, antithrombin, prothrombin fragment 1 + 2, thrombin-antithrombin complex, plasmin inhibitor, neutrophil-activating peptide 2, and platelet-monocyte complexes were drawn preoperatively, 30 min, and 3 h postoperatively and approximately 20 h postoperatively. Elderly patients had an increased activation of the hemostatic system. In particular, elderly patients showed a more pronounced increase in fibrinolysis and platelet activation postoperatively compared with younger patients.

Adult↗
PubMed2005

Serious foetal growth restriction is associated with reduced proportions of natural killer cells in decidua basalis.

Extravillous trophoblasts are major participants in placental development and remodelling of spiral arteries. Trophoblast invasion is regulated by maternal immune cells, and abnormal leucocyte subpopulation composition has been reported in implantation failure. In pre-eclampsia (PE), with or without foetal growth restriction (FGR), superficial trophoblast invasion and insufficient remodelling of spiral arteries are common findings. In the present study, we have compared spiral artery remodelling and leucocyte composition in decidual tissue from 30 cases (PE=8, FGR=5, PE + FGR=17) and 31 controls. Six histological remodelling criteria were established, and each pregnancy obtained a remodelling score. Numbers of natural killer (NK) cells (CD56+), T cells (CD3+) and activated (CD25+ or CD69+) leucocytes were determined and related to total leucocyte (CD45+) numbers in serial sections. Cases demonstrated significantly impaired spiral artery remodelling, inappropriate placental growth and reduced NK cell proportions, as compared to controls (P=0.02, P<0.001 and P=0.01, respectively). Reduced NK cell proportion was primarily found in pregnancies complicated by FGR, with or without PE, and a significant positive correlation was observed between NK cell proportion, trophoblast infiltration and placental growth. Our in vivo observations support the hypothesized association between NK cells, impaired placental development and pathogenesis of PE/FGR.

Adult↗
PubMed2004

[Prevalence of refractive errors in Norway].

BACKGROUND: The aim of this study was to determine the prevalence of refractive errors among young and middle-aged adults in Norway. MATERIAL AND METHODS: Refractive errors were measured with an autorefractor in a population-based sample of young (20-25 years) and middle-aged (40-45 years) adults participating in a health study (HUNT) conducted in Nord-Trøndelag county in Norway in 1996-97. RESULTS: A total of 3137 persons (1248 young and 1889 middle-aged adults) with corrected visual acuity >0.5 (in either eye) were included. About half of the population (51.8% among the young and 52.3% among the middle-aged adults) were emmetropic. The prevalence of myopia was 35.0% in the young adult group and 30.3% in the middle-aged group. Myopia was significantly higher in women aged 20-25 years (36.4%) than in men aged 40-45 years (28.1%). Prevalence of hyperopia increased with age from 13.2% (20-25 years) to 17.4% (40-45 years). INTERPRETATION: The results show a relative high prevalence of myopia in the general population of Norway.

Adult↗
PubMed2004

Cytological criteria for the diagnosis of intraductal hyperplasia, ductal carcinoma in situ, and invasive carcinoma of the breast.

The advent of mammography screening presents a diagnostic challenge to the cytopathologist as an increasing proportion of breast lesions requiring investigation will be nonpalpable and up to 40% will be accounted for by atypical intraductal hyperplasia and ductal carcinoma in situ, as opposed to previously, when these lesions represented less than 10% of palpable tumors. We studied 133 fine-needle aspirates from breast tumors and found that nuclear morphology, myoepithelial cells, signs of invasion, and degree of cellular dissociation are among the most potent factors discriminating between benign epithelial proliferations, atypical intraductal hyperplasia, ductal carcinoma in situ, and invasive carcinoma.

Biopsy, Fine-Needle↗