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V Andersen

Publications and source records attributed to V Andersen.

At least 19 recordsLinked to original sources
PubMed2005

The FLUKA code: new developments and application to 1 GeV/n iron beams.

The modeling of ion transport and interactions in matter is a subject of growing interest, driven by the continuous increase of possible application fields. These include hadron therapy, dosimetry, and space missions, but there are also several issues involving fundamental research, accelerator physics, and cosmic ray physics, where a reliable description of heavy ion induced cascades is important. In the present work, the capabilities of the FLUKA code for ion beams will be briefly recalled and some recent developments presented. Applications of the code to the simulation of therapeutic carbon, nitrogen and oxygen ion beams, and of iron beams, which are of direct interest for space mission related experiments, will be also presented together with interesting consideration relative to the evaluation of dosimetric quantities. Both applications involve ion beams in the AGeV range.

Carbon↗
PubMed2005

The application of FLUKA to dosimetry and radiation therapy.

The FLUKA Monte Carlo code has been evolving over the last several decades and is now widely used for radiation shielding calculations. In order to facilitate the use of FLUKA in dosimetry and therapy applications, supporting software has been developed to allow the direct conversion of the output files from standard CT-scans directly into a voxel geometry for transport within FLUKA. Since the CT-scan information essentially contains only the electron density information over the scanned volume, one needs the specific compositions for each voxel individually. We present here the results of a simple algorithm to assign tissues in the human body to one of four categories: soft-tissue, hard-bone, trabecular-bone and porous-lung. In addition, we explore the problem of the pathlength distributions in porous media such as trabecular bone. A mechanism will be implemented within FLUKA to allow for variable multipal fixed density materials to accommodate the pathlength distributions discovered.

Algorithms↗
PubMed2004

The FLUKA code for space applications: recent developments.

The FLUKA Monte Carlo transport code is widely used for fundamental research, radioprotection and dosimetry, hybrid nuclear energy system and cosmic ray calculations. The validity of its physical models has been benchmarked against a variety of experimental data over a wide range of energies, ranging from accelerator data to cosmic ray showers in the earth atmosphere. The code is presently undergoing several developments in order to better fit the needs of space applications. The generation of particle spectra according to up-to-date cosmic ray data as well as the effect of the solar and geomagnetic modulation have been implemented and already successfully applied to a variety of problems. The implementation of suitable models for heavy ion nuclear interactions has reached an operational stage. At medium/high energy FLUKA is using the DPMJET model. The major task of incorporating heavy ion interactions from a few GeV/n down to the threshold for inelastic collisions is also progressing and promising results have been obtained using a modified version of the RQMD-2.4 code. This interim solution is now fully operational, while waiting for the development of new models based on the FLUKA hadron-nucleus interaction code, a newly developed QMD code, and the implementation of the Boltzmann master equation theory for low energy ion interactions.

Computer Simulation↗
PubMed2004

Overview of the Martian radiation environment experiment.

Space radiation presents a hazard to astronauts, particularly those journeying outside the protective influence of the geomagnetosphere. Crews on future missions to Mars will be exposed to the harsh radiation environment of deep space during the transit between Earth and Mars. Once on Mars, they will encounter radiation that is only slightly reduced, compared to free space, by the thin Martian atmosphere. NASA is obliged to minimize, where possible, the radiation exposures received by astronauts. Thus, as a precursor to eventual human exploration, it is necessary to measure the Martian radiation environment in detail. The MARIE experiment, aboard the 2001 Mars Odyssey spacecraft, is returning the first data that bear directly on this problem. Here we provide an overview of the experiment, including introductory material on space radiation and radiation dosimetry, a description of the detector, model predictions of the radiation environment at Mars, and preliminary dose-rate data obtained at Mars.

Astronauts↗
PubMed2002

Cancer risk among patients with IgA deficiency or common variable immunodeficiency and their relatives: a combined Danish and Swedish study.

The extremely high risk reported for some types of cancer among patients with common variable immunodeficiency (CVID) is based on a limited number of investigations. Therefore, we examined the risks for cancer among 562 Danish and Swedish patients with CVID or IgA deficiency and 2071 relatives in 1958-96. The patients were identified through an Immunodeficiency Register and hospital records, while the relatives were traced through population registers. Cancer incidence was assessed by linkage to the Cancer Registries and compared with that in the general population. Among 386 patients with IgA deficiency, the incidence of cancer was not increased (standardized incidence ratio (SI) = 1.0); but two cases of stomach cancer were found, resulting in a non-significant increase in risk (SIR = 5.4; 95% CI = 0.7-19.5). Among 176 patients with common variable immunodeficiency (CVID), the incidence of cancer at all sites combined was increased (SIR = 1.8; 95% CI = 1.0-2.9), which was due mainly to significant excesses of malignant lymphoma (obs = 4; SIR = 12.1; 95% CI = 3.3-31.0) and of stomach cancer (obs = 3; SIR = 10.3; 95% CI = 2.1-30.2). Among the 626 relatives of patients with CVID, no increase in risk was found for these types of cancer or for cancer overall (obs = 53; SIR = 1.0; 95% CI = 0.8-1.3). Our data show that the risks for malignant lymphoma and stomach cancer among patients with CVID may be lower than reported previously. The absence of an increased risk among relatives suggests that the increased cancer morbidity in patients with CVID is related to the immunodeficiency per se rather than to specific genetic traits shared with their relatives.

Adult↗
PubMed2001

Spontaneous reports on drug-induced pancreatitis in Denmark from 1968 to 1999.

OBJECTIVES: To present an update on drug-induced pancreatitis reported to the Danish Committee on Adverse Drug Reactions. DESIGN: Retrospective study of spontaneous case reports to the Danish reporting system on adverse drug reactions. METHODS: All cases of suspected drug-induced pancreatitis reported to the Danish Committee on Adverse Drug Reactions from 1968 to 1999 were analysed. Three cases were excluded leaving 47 cases for analysis. RESULTS: Drug-induced pancreatitis made up 0. 1% of all the reports to the committee from 1968 to 1999. The proportion seemed to increase and was 0.3% during the last 8 years. The 47 cases corresponded to 0.1% of the number of patients discharged due to pancreatic disease (without cancers) per year in Denmark. Serious courses were frequent as indicated by death and hospitalisation being reported in 4 (9%) and 32 (68%) cases, respectively. Death occurred after valproate (two cases), clomipramine (one case) and azathioprine (one case). Definite relationship was stated for mesalazine (three cases), azathioprine (two cases) and simvastatin (one case) on the basis of re-challenge. A possible or probable causality was considered for a further 30 drugs including 5-acetylsalicylic acid agents, angiotensin-converting enzyme inhibitors, estrogen preparations, didanosine, valproate, codeine, antiviral agents used in acquired immunodeficiency syndrome therapy, various lipid-reducing agents, interferon, paracetamol, griseofulvin, ticlopine, allopurinol, lithium and the MMR (measles" mumps/rubella) vaccination. CONCLUSION: Drug-induced pancreatitis is rarely reported. The incidence may be increasing and the course is often serious. This is the first report on definite simvastatin-induced pancreatitis. Further studies on the pancreotoxic potential of drugs are warranted.

Adverse Drug Reaction Reporting Systems↗
PubMed2001

Urea synthesis in patients with chronic pancreatitis: relation to glucagon secretion and dietary protein intake.

BACKGROUND & AIMS: Up-regulation of urea synthesis by amino acids and dietary protein intake may be impaired in patients with chronic pancreatitis (CP) due to the reduced glucagon secretion. Conversely, urea synthesis may be increased as a result of the chronic inflammation. The aims of the study were to determine urea synthesis kinetics in CP patients in relation to glucagon secretion (study I) and during an increase in protein intake (study II). METHODS: In study I, urea synthesis rate, calculated as urinary excretion rate corrected for accumulation in total body water and intestinal loss, was measured during infusion of alanine in 7 CP patients and 5 control subjects on spontaneous protein intake. The functional hepatic nitrogen clearance (FHNC), i.e. urea synthesis expressed independent of changes in plasma amino acid concentration, was calculated as the slope of the linear relation between urea synthesis rate and plasma alpha -amino nitrogen concentration. In study II, 6 of the patients of study I had urea synthesis and FHNC determined before and after a period of 14 days of supplementation with a protein-enriched liquid (dietary sequence randomized). RESULTS: Study I: Alanine infusion increased urea synthesis rate by a factor of 10 in the control subjects, and by a factor of 5 in the CP patients (P<0.01). FHNC was 31.9+/-2.4 l/h in the control subjects and 16.5+/-2.0 l/h (P<0.05) in the CP patients. The glucagon response to alanine infusion (AUC) was reduced by 75 % in the CP patients. The reduction in FHNC paralleled the reduced glucagon response (r(2)=0.55, P<0.01). Study II: The spontaneous protein intake was 0.75+/-0.14 g/(kg x day) and increased during the high protein period to 1.77+/-0.12 g/(kg x day). This increased alanine stimulated urea synthesis by a factor of 1.3 (P<0.05), FHNC from 13.5+/-2.6 l/h to 19.4+/-3.1 l/h (P<0.01), and the glucagon response to alanine infusion (AUC) by a factor of 1.8 (P<0.05). CONCLUSIONS: Urea synthesis rate and FHNC are markedly reduced in CP patients. This is associated with, and probably a result of, impaired glucagon secretion, and predicts a lower than normal postprandial hepatic loss of amino nitrogen. An increase in dietary protein intake increases alanine stimulated urea synthesis and FHNC by a mechanism that involves an increase in glucagon. This indicates that the low FHNC during spontaneous protein intake included an adaptation to the low protein intake, effectuated by a further decrease in glucagon secretion.

Adaptation, Physiological↗
PubMed2000

Female bluethroats enhance offspring immunocompetence through extra-pair copulations.

Female birds frequently copulate with extra-pair males, but the adaptive value of this behaviour is poorly understood. Some studies have suggested that 'good genes' may be involved, where females seek to have their eggs fertilized by high-quality males without receiving any material benefits from them. Nevertheless, it remains to be shown that a genetic benefit is passed on to offspring. Here we report that nestling bluethroats, Luscinia svecica, sired by extra-pair males had a higher T-cell-mediated immune response than their maternal half-siblings raised in the same nest. The difference could not be attributed to nestling body mass, sex or hatching order, but may be an effect of paternal genotype. Extra-pair young were also more immunocompetent than their paternal half-sibs raised in the genetic father's own nest, which indicates an additional effect of maternal genotype. Our results are consistent with the idea that females engage in extra-pair copulations to obtain compatible viability genes, rather than 'good genes' per se.

Animals↗
PubMed2000

Two edged role of mannose binding lectin in rheumatoid arthritis: a cross sectional study.

OBJECTIVE: We investigated whether polymorphisms in the gene of mannose binding lectin (MBL) may be associated with onset of rheumatoid arthritis (RA), and whether MBL in conjunction with aggregated agalactosyl IgG (IgG-G0) may be associated with clinical and paraclinical variables. METHODS: MBL genotypes and serum concentrations were measured by polymerase chain reaction and ELISA in 189 patients with established RA. Binding of purified MBL to IgG-G0 in serum was assessed and clinical and paraclinical variables were recorded. RESULTS: The median age at onset of RA in the 3 genotypes (normal: A/A, hetero: A/0, and homozygous: 0/0 for variant alleles) was 54.1 (n = 108), 47.0 (n = 68), and 38.4 years (n = 13), respectively (p = 0.01). The frequency of variant alleles in patients with onset below the median age (50.8 yrs) was 0.32, but was 0.17 in patients with onset above 50.8 years (p = 0.003) and 0.20 in 250 controls (p = 0.001). Stratification according to erosion score (no, small, large) revealed an increasing tendency among the different groups in binding of MBL to IgG-G0, increased Health Assessment Questionnaire score, and acute phase reactants in A/A individuals, while no difference was seen among carriers of variant alleles. This effect was most pronounced in those with late onset RA. CONCLUSION: Presence of MBL variant alleles was associated with early onset of RA. MBL deficiency may, therefore, accelerate the disease. However, in patients with late onset and advanced disease our results indicate that the A/A type may be associated with additional inflammation different from that seen in carriers of variant alleles.

Adult↗
PubMed1999

Mannose-binding lectin polymorphisms and susceptibility to infection in systemic lupus erythematosus.

OBJECTIVE: To determine whether variant alleles in the coding portion of the mannose-binding lectin (MBL) gene are associated with increased susceptibility to systemic lupus erythematosus (SLE) and concomitant infections. METHODS: MBL alleles and serum concentrations were determined by polymerase chain reaction and enzyme-linked immunosorbent assay, respectively, in 91 Danish patients with SLE and in 250 controls. RESULTS: Homozygosity for MBL variant alleles was observed in 7.7% of the SLE patients compared with 2.8% of the controls (P = 0.06), while no difference was seen for heterozygosity (33.0% versus 34.4%). Homozygotes had an increased risk of acquiring serious infections compared with patients who were heterozygous or homozygous for the normal allele (odds ratio 8.6, 95% confidence interval 1.5-47.6, P = 0.01). The time interval from the diagnosis of SLE to the first infectious event was shorter (P = 0.017), and the annual number of infectious events was 4 times higher, among homozygotes (P = 0.00002). They were especially prone to acquire pneumonia (P = 0.00004). CONCLUSION; Homozygosity for MBL variant alleles may explain much of the increased risk of complicating infections seen in SLE patients. Additionally, it is a minor risk factor for acquiring SLE.

Adolescent↗
PubMed1999

Antipyrine, oxazepam, and indocyanine green clearance in patients with chronic pancreatitis and healthy subjects.

BACKGROUND: Hepatic drug metabolism was examined in patients with chronic pancreatitis and healthy controls by using a cocktail design with three different model compounds: antipyrine to express phase-I oxidation, oxazepam to express phase-II conjugation, and indocyanine green (ICG), a high-clearance compound. METHODS: Eight patients with chronic pancreatitis and seven healthy controls participated. Patients were diagnosed by the presence of typical morphologic changes of the pancreas on imaging and had a moderately but significantly reduced exocrine function and no or only slight impairment of the glucose tolerance. No one had a history or clinical signs of liver disease. Clearance of the three model compounds was estimated after the administration of 1 g antipyrine and 15 mg oxazepam orally and a bolus of indocyanine green, 0.5 mg/kg body weight, intravenously. RESULTS: The antipyrine clearance and ICG clearance were significantly decreased in the patients compared with the controls (mean, 27.2 ml/min; 95% confidence interval (CI), 19.4-35; versus 46.2 ml/min; 34.7-58.7, and 501 ml/min; 4014601, versus 771 mU/min; 677-865 (P < 0.05), respectively). The oxazepam clearance did not differ significantly between the two groups (181 ml/min (145-217) versus 178 ml/min (152-204)). The model drug clearance ratios between the patient and control clearances showed decreased values for antipyrine and ICG compared with the oxazepam data (0.59 and 0.65 versus 1.02, respectively). Patients and controls were characterized by a body weight of 58.2 kg (53.1-63.3) and 83.4 kg (72.7-94.1), respectively, and a body mass index (BMI) of 19.6 kg/m2 (17.9-21.3) versus 25.9 kg/m2 (23.4-28.4) (P < 0.05 for both). CONCLUSIONS: Patients with chronic pancreatitis characterized by a moderately reduced exocrine function and absence of diabetes mellitus and overt liver disease had a decreased antipyrine oxidation and ICG clearance, whereas no difference was seen in oxazepam conjugation when compared with healthy volunteers. In chronic pancreatitis the hepatic phase-I oxidation is reduced compared with the phase-II conjugation, as shown by the model drug clearance ratios. The clearance of ICG was also affected, pointing at a reduced hepatic plasma flow, provided that the hepatic extraction fraction is normal for these patients.

Adult↗
PubMed1999

Liver volume, portal vein flow, and clearance of indocyanine green and antipyrine in hyperthyroidism before and after antithyroid treatment.

BACKGROUND: The aim of the study was to examine liver volume, portal vein flow, and indocyanine green (ICG) and antipyrine clearance in hyperthyroidism before and after antithyroid drug treatment. METHODS: Liver volume and blood flow in the portal vein were investigated in nine fasting patients with hyperthyroidism by means of computed tomography scan and Doppler ultrasound, respectively. ICG clearance was estimated by bolus injection of ICG (0.5 mg/kg body weight) and antipyrine clearance with a one-sample technique. All patients were investigated before and after 3 months of antithyroid treatment, when euthyroidism had been achieved. The Wilcoxon matched-pairs test was used for statistical analysis. RESULTS: The median liver volume increased by 238 (155-289) ml (median, 95% confidence interval), corresponding to 19%, and the weight by 5.0 (0.0-8.0) kg (8%), and the antipyrine clearance decreased by 8 (3.1-34.4) ml/min (16%). These changes were all significant (P < 0.05). The relation between liver volume and body weight increased from 19.9 (16.5-23.7) ml/kg to 21.4 (17.1-21.9) ml/kg (P = 0.11). The liver blood flow as estimated by ICG clearance and Doppler ultrasound was not altered significantly after the treatment period (P = 0.07 and 0.77, respectively). CONCLUSIONS: The liver volume increased by 19% in nine hyperthyroid patients during treatment with antithyroids. Antipyrine clearance was reduced by 16%, whereas liver blood flow, as estimated by ICG clearance and Doppler ultrasound examination of portal vein flow, was not significantly altered. A differential regulation of liver volume and oxidative metabolic capacity in hyperthyroidism was seen.

Adult↗
PubMed1998

Cytokine-mediated PGE2 expression in human colonic fibroblasts.

We investigated prostanoid biogenesis in human colonic fibroblasts (CCD-18Co and 5 primary fibroblast cultures) and epithelial cell lines (NCM460, T84, HT-29, and LS 174T) and the effect of PGE2 on fibroblast morphology. Cytokine-stimulated PGE2 production was measured. PGH synthase-1 and -2 (PGHS-1 and -2) protein and mRNA expression were evaluated. Basal PGE2 levels were low in all cell types (0.15-6.47 ng/mg protein). Treatment for 24 h with interleukin-1beta (IL-1beta; 10 ng/ml) or tumor necrosis factor-alpha (50 ng/ml), respectively, elicited maximal 25- and 6-fold inductions of PGE2 synthesis in CCD-18Co cultures and similar results in primary fibroblast cultures; maximal inductions with IL-1beta in colonic epithelial cell lines were from zero to fivefold. Treatment of CCD-18Co fibroblasts with IL-1beta caused maximal 21- and 53-fold increases, respectively, in PGHS-2 protein and mRNA levels without altering PGHS-1 expression. PGE2 (0.1 micromol/l) elicited a dramatic shape change in selected fibroblasts. Colonic fibroblasts are potentially important as cytokine targets and a source of and target for colonic prostanoids in vivo.

Cell Line↗
PubMed1998

CC chemokine receptor 5 polymorphism in rheumatoid arthritis.

OBJECTIVE: Some chemokine receptors have been shown to be co-receptors for human immunodeficiency virus (HIV-1). A 32 base pair deletion allele in the CC chemokine receptor 5 gene (CCR5 delta32 allele) affects both transmission of HIV-1 and acquired immunodeficiency syndrome (AIDS)-free survival. Chemokines are suggested to be critical for establishment of inflammatory processes in autoimmune diseases such as rheumatoid arthritis (RA). We hypothesized that the defective allele may modulate the inflammatory process in RA. METHODS: Using polymerase chain reaction methods, we investigated the significance of the CCR5 delta32 allele in 163 Danish patients with RA and monitored clinical and paraclinical variables. RESULTS: The gene frequency of the CCR5 delta32 allele (0.10) did not deviate significantly from healthy controls and from that reported in healthy Caucasian populations, nor did the distribution deviate from the Hardy-Weinberg predictions (131 wild type, 30 heterozygous, 2 homozygous for the deletion allele; p = 0.85). However, a significantly increased proportion of those carrying the deletion allele were negative for IgM rheumatoid factor (RF) compared to those homozygous for the normal allele (29 vs 9%; p = 0.007). The proportion of CCR5 delta32 allele carriers with swollen joints was decreased compared to those homozygous for the normal allele (35 vs 58%, respectively; p = 0.03), as was the duration of morning stiffness (median 0 vs 60 min, respectively; p = 0.0002). CONCLUSION: The CCR5 delta32 allele seems to have some influence on RA variables including RF, which suggests that inhibition of chemokine receptors might be a potential target for disease modifying therapy in RA.

Adult↗
PubMed1997

Non-Hodgkin's lymphoma and other cancers among a cohort of patients with systemic lupus erythematosus.

OBJECTIVE: To investigate whether systemic lupus erythematosus (SLE) is associated with non-Hodgkin's lymphoma or other malignant neoplasms. METHODS: Data on a cohort of 1,585 patients with SLE from the nationwide Danish Hospital Discharge Register were linked to information in the Danish Cancer Registry to determine the occurrence of cancer during up to 15 years of followup. The expected number of cancers was calculated from accumulated person-years and national cancer incidence rates. RESULTS: There was a significant excess of non-Hodgkin's lymphoma among the SLE patients, based on 8 cases observed against 1.5 expected (relative risk [RR] 5.2, 95% confidence interval 2.2-10.3). In addition, a significantly increased RR was found for cancer of the lung (RR 1.9; n = 15), the liver (RR 8.0; n = 5), and the vagina/vulva (RR 5.7; n = 3). CONCLUSION: There seemed to be a positive association between SLE and non-Hodgkin's lymphoma. Other cancers with a possible virus-related etiology, such as liver and vaginal/vulva cancer, were also observed in excess. In addition, there was an indication of an increased risk of lung cancer among patients who were hospitalized for SLE.

Adolescent↗