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Biomedical subjects

V Hansen

Publications and source records attributed to V Hansen.

At least 19 recordsLinked to original sources
PubMed2006

Structure analysis of embedded nano-sized particles by precession electron diffraction. eta'-precipitate in an Al-Zn-Mg alloy as example.

The Vincent-Midgley precession technique has been used to collect three-dimensional electron diffraction intensity data from a dispersion of coherent precipitates in a matrix. In order to suppress severe effects from multiple diffraction via matrix reflections, a fairly large precession (tilt) angle had to be used. This implied a high background from the surrounding matrix, and limited the number of reflections that could be measured from patterns on image plates. The heavily faulted hexagonal eta'-precipitates (a = 0.496 nm, c = 1.405 nm) with thickness 3-5 nm occur in four equivalent orientations relative to the aluminium matrix; with frequent overlap of reflections. A model of the average structure in the space group P6(3)/mmc with assumed composition Mg(2)Zn(5-x)Al(2+x), have been derived by Patterson analysis and intensity comparisons.

Journal Article↗
PubMed2004

No association of the SOD1 locus and disease susceptibility or phenotype in sporadic ALS.

Mutations in the copper zinc superoxide dismutase gene (SOD1) are found in 20% of familial and 3% of sporadic ALS patients. SOD1 protein aggregation can be detected in motor neurons of mutation-negative sporadic cases but a pathogenic role for wild-type SOD1 in ALS has not been demonstrated. In this study of 233 ALS cases and 248 controls the authors found no significant association between four individual single nucleotide polymorphisms and a deletion spanning the SOD1 locus (or their combined haplotypes), and disease susceptibility, or phenotype.

Amyotrophic Lateral Sclerosis↗
PubMed2004

Generic UMTS test signal for RF bioelectromagnetic studies.

This report outlines the characteristics of universal mobile telecommunications system (UMTS) signals and discusses the signal parameters with respect to their possible biological relevance in order to define a generic UMTS test signal (GUS) for experiments aiming at the investigation of biological effects of weak electromagnetic fields. The GUS includes features of a real UMTS signal and especially the characteristics of UMTS, which differ from those of already applied second generation mobile communication systems (GSM 900, DCS1800, PCS1900, IS-95). It has been specified on the basis of the recommendations of a working group of the German Forschungsgemeinschaft Funk (FGF) with a focus on the mechanisms of UMTS which are responsible for slow term signal contributions, i.e., low frequency variations of the radio frequency (RF) envelope, since the hypothetical possibility of biological relevance of weak electromagnetic fields is often attributed to time variations of the RF envelope with frequencies close to those of natural processes. In this respect, it is also shown that the mandatory power control loop in UMTS gives rise to very strong 1.5 kHz variations on the air interface. Based upon the concept of the GUS, a UMTS test signal generator (GUS6960S) is described.

Cell Phone↗
PubMed2004

The precession technique in electron diffraction and its application to structure determination of nano-size precipitates in alloys.

Crystal structure of nano-scale precipitates in age-hardening aluminum alloys is a challenge to crystallography. The utility of selected area electron diffraction intensities from embedded precipitates is limited by double scattering via matrix reflections. This effect can be signally reduced by the precession technique, which we have used to collect extensive intensity data from the semicoherent, metastable eta-precipitate in the Al-Zn-Mg alloy system. A structure model in the space group P-62c is proposed from high-resolution microscopy and electron diffraction intensities. The advantages of using the precession technique for quantitative electron diffraction is discussed.

Alloys↗
PubMed2004

Emission of phthalates from PVC and other materials.

The main objective of this study was to generate quantitative and qualitative emission data on phthalates from different materials. To achieve this the existing (Chamber for Laboratory Investigations of Materials, Pollution and Air Quality) Climpaq-based procedure for simplified measurements of emissions of plasticizer from PVC and other plasticized materials was modified. It was applied to a range of products. Some of them were suspected of contributing to the indoor concentration of plasticizers. The emissions from PVC flooring, polyolefine flooring, a refrigerator list, two electric cables, PVC skirting and floor wax were studied in separate Climpaqs. The emission from the PVC flooring in the Climpaq was compared with results from the ultra-small chamber Field and Laboratory Emission Cell (FLEC). Sampling and analysis methods were optimized to measure plasticizers. Samples were taken in exhaust air from the chambers after 6, 35, 62, 105, and 150 days from the start of the experiment. PVC flooring was tested for an additional 100 days. Polyolefine covered with wax resulted in an air concentration of 22 microg/m3 of dibutylphthalate (DBP), which is two orders of magnitude larger than any other materials, but did not emit di(2-ethylhexyl)phthalate (DEHP). The other materials resulted in max concentration of approximately 1 microg/m3 of DEHP and low emissions of DBP. The concentration of DEHP in each chamber increased slowly to a rather stable level which was reached after 150 days. DBP concentrations in the chambers with PVC skirting, PVC flooring, polyolefine and floor wax reached their quasi-static equilibrium after 60 days. The modified method did not create sufficient data for the calculation of emission rates. Adsorption of emission on chamber surfaces made it impossible to use the first part of the experiment for emission rate calculation. When the concentration had stabilized, it was found to be almost identical and independent of chamber and ventilation rate. Emission rates were reduced at high concentrations probably because the concentration in the material was near equilibrium with the concentration in the chamber air.

Air Pollution, Indoor↗
PubMed2002

A case of early congenital syphilis.

A case of early congenital syphilis is reported in order to emphasize that syphilis is still present nowadays and that detection of syphilis in pregnant women is primordial for the prevention of this disease.

Female↗
PubMed2001

[Feeling of illness after hysterectomy. Women's own assessment].

INTRODUCTION: The aim of the study was to investigate the time interval from the operation to no feeling of illness at all in a population of women, who had undergone a total abdominal or vaginal hysterectomy. MATERIAL AND METHODS: Data on 361 women who had had a total abdominal or vaginal hysterectomy during the period, 1.1.1998 to 31.3.1999 were collected from a regional database. Those born before 1.1.1940, presented with a genital malignancy, had a diagnosis of genital prolapse, or received surgery in addition to the hysterectomy were excluded. Four months after the hysterectomy, all the women were sent a questionnaire asking about the time of returning to work and the complete absence of any feeling of illness. This information was related to selected perioperative data. Women who had had a total abdominal hysterectomy were not statistically comparable with those who had had a vaginal hysterectomy. RESULTS: A total of 313 women participated (87%). After a total abdominal hysterectomy, 92%, 80%, and 35% had a subjective feeling of illness at four, six, and ten weeks, respectively. The median duration of feeling ill was nine weeks. The figures after a vaginal hysterectomy were 85%, 71%, and 18%, with a median duration of feeling ill of seven weeks. Only peroperative blood loss and the presence of postoperative complications related statistically to the duration of feeling ill. CONCLUSION: The interval between the operation and no feeling of illness at all after a total abdominal or vaginal hysterectomy is longer than was formerly believed. Further investigation is recommended.

Convalescence↗
PubMed2001

Prevalence of serious psychiatric morbidity in attenders and nonattenders to a health survey of a general population : the Tromsø Health Study.

The objective was to study the effect of serious psychiatric disorders on participation in a general health population study. This was done by linking the records of the Second Tromsø Health Study to the case register of a mental hospital. The participants in the Second Tromsø Health Study were 21,441 persons, the total population of men aged 20-54 and women aged 20-49 years who resided in Tromsø, Norway, in 1979. The authors found that both men and women with psychiatric illness had approximately 20% lower attendance rates. Nonattenders to the survey had 2.5 times higher prevalence of psychiatric disorders than did attenders of both sexes. Age, marital status, and various psychiatric diagnoses were all significant predictors of nonattendance. Nonattendance led to underestimation of the prevalence of psychiatric disorders in the population. The conclusion is that in general health studies, even those with high attendance rates, the estimates of prevalence of psychiatric disorders in the population are seriously affected by nonattendance. Prevalence ratios between groups of the population were not much affected by nonattendance.

Adult↗
PubMed2001

Marine n-3 fatty acids, wine intake, and heart rate variability in patients referred for coronary angiography.

BACKGROUND: Dietary n-3 polyunsaturated fatty acids (PUFAs) derived from fish may reduce the incidence of sudden cardiac death (SCD). In addition, wine drinking is suggested to have a protective effect against cardiovascular death. METHODS AND RESULTS: We included 291 patients referred for coronary angiography in whom ischemic heart disease was suspected and all of whom completed a food questionnaire regarding fish and wine intake. The n-3 PUFA composition of granulocyte membranes and of adipose tissue was measured. In addition, 24-hour heart rate variability (HRV) was analyzed. Fish intake was positively associated with the level of n-3 PUFAs in adipose tissue. Significant positive correlation coefficients were found between HRV indices and the levels of n-3 PUFAs in granulocytes. Wine intake was also significantly positively related to HRV, but the patients with the highest wine intake also had the highest intake of fish, as documented by a high n-3 PUFA content in adipose tissue. Multiple linear regression analysis revealed that traditional factors such as treatment with ss-blockers, smoking, age, and previous myocardial infarction were independently related to HRV, and furthermore that n-3 PUFAs (but not wine intake) were significantly independently associated with HRV. CONCLUSIONS: The close positive association between n-3 PUFAs and HRV in patients suspected of having ischemic heart disease may indicate a protective effect of n-3 PUFAs against SCD. This may partly explain the reduction in SCD observed in humans with a modest intake of n-3 PUFA. Wine intake was also positively correlated with HRV, but this correlation was no longer significant after controlling for the cellular level of n-3 PUFA.

Aged↗
PubMed2001

Responses to the Seasonal Pattern Assessment Questionnaire in different seasons.

OBJECTIVE: The study investigated whether results on the Seasonal Pattern Assessment Questionnaire, which is used for diagnosis of seasonal affective disorder, differed by the season in which the questionnaire was completed. METHOD: Every third month from March 1997 to February 1998, a population-based panel of 200 men and women age 27-72 years in Gamvik, northern Norway, completed a standardized questionnaire that included all items from the Seasonal Pattern Assessment Questionnaire. RESULTS: The average score for seasonal affective disorder changed over the year. The difference between the highest score, in March, and the lowest, in September, was 8.8%. CONCLUSIONS: Results on the Seasonal Pattern Assessment Questionnaire varied by season, but did not vary by seasonal differences in the amount of daylight.

Adult↗
PubMed2001

Cause-specific mortality in psychiatric patients after deinstitutionalisation.

BACKGROUND: Since the late 1970s, the psychiatric service system in Norway has been changed gradually according to the principles of deinstitutionalisation. AIMS: To document the mortality of psychiatric patients in a deinstitutionalised service system. METHODS: The case register of a psychiatric hospital covering the period 1980-1992 was linked to the Central Register of Deaths. Age-adjusted death rates and standardised mortality ratios (SMRs) were computed. RESULTS: Patients with organic psychiatric disorders had significantly higher mortality regardless of cause of death. SMRs ranged from 0.9 for death by cancer in women to 36.3 for suicide in men. For unnatural death, SMRs were highest in the first year after discharge. Compared to the periods 1950-1962 and 1963-1974, there has been an increase in SMRs for cardiovascular death and suicide in both genders. CONCLUSIONS: Deinstitutionalisation seems to have had as its cost a relative rise both in cardiovascular death and unnatural deaths for both genders, but most pronounced in men.

Age Distribution↗
PubMed2001

Formation of strong airway irritants in mixtures of isoprene/ozone and isoprene/ozone/nitrogen dioxide.

We evaluated the airway irritation of isoprene, isoprene/ozone, and isoprene/ozone/nitrogen dioxide mixtures using a mouse bioassay, from which we calculated sensory irritation, bronchial constriction, and pulmonary irritation. We observed significant sensory irritation (approximately 50% reduction of mean respiratory rate) by dynamically exposing the mice, over 30 min, to mixtures of isoprene and O3 or isoprene, O3, and NO2. The starting concentrations were approximately 4 ppm O3 and 500 ppm isoprene (+ approximately 4 ppm NO2. The reaction mixtures after approximately 30 sec contained < 0.2 ppm O3. Addition of the effects of the residual reactants and the identified stable irritant products (formaldehyde, formic acid, acetic acid, methacrolein, and methylvinyl ketone) could explain only partially the observed sensory irritation. This suggests that one or more strong airway irritants were formed. It is thus possible that oxidation reactions of common unsaturated compounds may be relevant for indoor air quality.

Air Pollution, Indoor↗
PubMed2001

[Screening for hemoglobinopathies in medical practice: audit of gynecologists, pediatricians and generalists in Brussels].

The haemoglobin disorders are frequent genetic diseases in tropical regions and in the mediterranean basin. They include thalassaemia and sickle cell disease. Because of important migrations of populations after the Second World War many big cities are confronted with the disease in West Europe nowadays. In Brussels where a neonatal screening has been organised in the majority of the maternity's, 45% of newborns have at least one parent originating from a region at risk for an haemoglobin disorder. One neonate among 2.000 is diagnosed with a major haemoglobinopathy at the screening. This rate is important and it appeared essential to evaluate the knowledge and need for complementary information among the doctors confronted with the disease. A survey was done in January 1999 and a questionnaire was sent to all gynaecologists, paediatricians and general practitioners in Brussels. The main results were a general self-evaluation of poor knowledge and a great need for complementary information. This survey was important to obtain adequate support of official health authorities in term of screening, prevention and financial aid to information campaigns. A consensus is needed among the different doctors for the best care possible of sick patients.

Attitude of Health Personnel↗
PubMed2001

[Prevention of hemoglobinopathies in Brussels: a necessity?].

Haemoglobinopathies are the most frequent genetic diseases in the world. The estimated frequency of carriers in the world is of 200 millions while there is about 300.000 births per year of major forms of haemoglobinopathies. The neonatal screening of haemoglobinopathies performed at the Hospital Erasme on around 80% of births in Brussels since 1994 has demonstrated that the frequency of carriers of an abnormal haemoglobin is around 1.5% while more than 1/2.000 newborns has a major haemoglobinopathy. A strategy must be adopted to manage the haemoglobinopathies in Brussels.

Algorithms↗
PubMed1999

Membrane potential and currents of isolated heart muscle cells exposed to pulsed radio frequency fields.

The influence of radio frequency (RF) fields of 180, 900, and 1800 MHz on the membrane potential, action potential, L-type Ca(2+) current and potassium currents of isolated ventricular myocytes was tested. The study is based on 90 guinea-pig myocytes and 20 rat myocytes. The fields were applied in rectangular waveguides (1800 MHz at 80, 480, 600, 720, or 880 mW/kg and 900 MHz, 250 mW/kg) or in a TEM-cell (180 MHz, 80 mW/kg and 900 MHz, 15 mW/kg). Fields of 1800 and 900 MHz were pulsed according to the GSM-standard of cellular phones. The specific absorption rates were determined from computer simulations of the electromagnetic fields inside the exposure devices by considering the structure of the physiological test arrangement. The electrical membrane parameters were measured by whole cell patch-clamp. None of the tested electrophysiological parameters was changed significantly by exposure to RF fields. Another physical stimulus, lowering the temperature from 36 degrees C to 24 degrees C, decreased the current amplitude almost 50% and shifted the voltage dependence of the steady state activation parameter d(infinity) and inactivation parameter f(infinity) of L-type Ca(2+) current by about 5 mV. However, at this lower temperature RF effects (900 MHz, 250 mW/kg; 1800 MHz, 480 mW/kg) on L-type Ca(2+) current were also not detected.

Action Potentials↗