Biomedical subjects

Olle Eriksson

Publications and source records attributed to Olle Eriksson.

10 recordsLinked to original sources

PubMed2006

Mast cell tryptase in postmortem serum-reference values and confounders.

We have investigated the effects of some factors suspected of inducing spuriously increased tryptase concentrations, specifically sampling site, conjunctival petechial bleeding and prone position at the time of death as indicators of premortem asphyxia, and resuscitation efforts by external cardiac massage. Tryptase was measured in blood from the femoral vein in 60 deaths: 39 control cases who died rapidly (within minutes) from natural causes (sudden cardiac death and acute aortic dissection), 16 with death caused by prolonged asphyxia (traumatic compression of the chest and suffocation due to body position or smothering), and five anaphylactic deaths. In 44 of these cases, tryptase was measured in both heart and femoral blood. Mast cell tryptase was analyzed with a commercial FEIA method (Pharmacia Diagnostics AB, Uppsala, Sweden) measuring both alpha- and beta-tryptase. Assuming that tryptase values in the control group were gamma distributed, we calculated the upper normal limits for tryptase concentrations in femoral blood. It was found that 95% of the controls had values below 44.3 mug/l (femoral blood), SD 5.27 mug/l. All but one of the anaphylactic deaths had tryptase concentrations exceeding that limit. Tryptase was significantly elevated in femoral blood from anaphylactic deaths (p<0.007), compared with the controls. Also, in the cases where death had occurred due to asphyxia tryptase was elevated in femoral blood (p<0.04). A significant difference in tryptase concentrations was seen between blood from the heart and the femoral vessels (p<0.02) in the whole material (n=44). Tryptase concentrations in femoral blood were not influenced by prone position at death, or resuscitation efforts. It is concluded that asphyxia premortem seems to affect tryptase concentrations, that postmortem tryptase measurements should be done in serum from femoral blood, and that the normal upper limit, covering 95%, is 44.3 microg/l.

Adolescent↗

PubMed2006

Mood changes correlate to changes in brain serotonin precursor trapping in women with premenstrual dysphoria.

The cardinal mood symptoms of premenstrual dysphoria can be effectively treated by serotonin-augmenting drugs. The aim of the study was to test the serotonin hypothesis of this disorder, i.e. of an association between premenstrual decline in brain serotonin function and concomitant worsening of self-rated cardinal mood symptoms. Positron emission tomography was used to assess changes in brain trapping of 11C-labeled 5-hydroxytryptophan, the immediate precursor of serotonin, in the follicular and premenstrual phases of the menstrual cycle in eight women with premenstrual dysphoria. Changes in mood and physical symptoms were assessed from daily visual analog scale ratings. Worsening of cardinal mood symptoms showed significant inverse associations with changes in brain serotonin precursor trapping; for the symptom "irritable", r(s)=-0.83, and for "depressed mood" r(s)=-0.81. Positive mood variables showed positive associations, whereas physical symptoms generally displayed weak or no associations. The data indicate strong inverse associations between worsening of cardinal symptoms of premenstrual dysphoria and brain serotonin precursor (11C-labeled 5-hydroxytryptophan) trapping. The results may in part support a role for serotonin in premenstrual dysphoria and may provide a clue to the effectiveness of serotonin-augmenting drugs in this disorder but should, due to small sample size and methodological shortcomings, be considered preliminary.

5-Hydroxytryptophan↗

PubMed2006

Perpendicular magnetocrystalline anisotropy in tetragonally distorted Fe-Co alloys.

We report on the experimental realization of tetragonal Fe-Co alloys as a constituent of Fe0.36Co0.64/Pt superlattices with huge perpendicular magnetocrystalline anisotropy energy, reaching 210 microeV/atom, and a saturation magnetization of 2.5 microB/atom at 40 K, in qualitative agreement with theoretical predictions. At room temperature the corresponding values and are achieved. This suggests that Fe-Co alloys with carefully chosen combinations of composition and distortion are good candidates for high-density perpendicular storage materials.

Journal Article↗

PubMed2005

Differential response to estrogen challenge test in women with and without premenstrual dysphoria.

This study tested the hypothesis that brain sensitivity to normal fluctuations in gonadal hormones is increased in women with premenstrual dysphoria. For this purpose, the effect of a common gonadal hormonal challenge on the sensitivity of the brain was investigated in 13 women with premenstrual dysphoria and 12 asymptomatic controls. The estrogen challenge test, comprising estradiolbenzoate 0.04 mg/kg, was given as an intramuscular gluteal injection between 0700 and 1000h on day 3 or 4 of the menstrual cycle; blood was sampled at 0, 0.6, 6.5, 24, 32, 48, 56, 72, 96, 120, and 144h and analyzed for estradiol, FSH and LH. Serum estradiol levels after the injection and the corresponding FSH responses were similar between the study groups; however, the LH responses were significantly different. Women with premenstrual dysphoria had a relatively stronger negative feedback response (p=0.014) up to the point of nadir LH levels (maximal negative feedback), but displayed higher LH levels at the nadir (p=0.01), more LH surge-like reactions (p=0.047), and a 50% higher area under the curve (AUC) for LH (p=0.03) than controls. The LH response in women with premenstrual dysphoria was related to the VAS-rated symptoms; the negative increment (AOC) correlated to luteal phase "bloating" (r(s)=0.73; p=0.0069) whereas the AUC of LH correlated to "irritability" (r(s)=0.58; p=0.040). A significant interaction term between study group and changes in LH during the negative feedback phase (32-0h), with regard to luteal phase "irritability" was found (test for interaction p=0.005). For the premenstrual dysphoria group, ratings of "depressed mood"were related to baseline FSH levels (r(s)=0.60; p=0.034), and to the AUC of FSH during the negative feedback phase (r(s)=0.58; p=0.043). Women with premenstrual dysphoria displayed a gonadotrophin response to estradiol challenge that differed from that of controls, and was correlated to symptom severity.

Adult↗

PubMed2004

Investigation of transcription factor AP-2 beta genotype in women with premenstrual dysphoric disorder.

It has repeatedly been shown that the serotonergic system is involved in the symptomatology of premenstrual dysphoric disorder (PMDD). Women with PMDD are reported to differ from symptom-free controls with regard to serotonin-related biological markers. Evidence from family and twin studies suggests a genetic contribution to the aetiology of PMDD. The expression of human transcription factor AP-2beta in neural crest cell lineages and neuroectodermal cells suggests that this protein may be of importance for functional characteristics of neurons by regulating the expression of target genes. Within the monoaminergic systems, several genes have binding sites for AP-2beta in regulatory regions, suggesting an involvement of AP-2beta in these systems. The gene encoding AP-2beta is located on chromosome 6p12-p21.1 and includes a polymorphic region consisting of a variable number of [CAAA] repeats located in the second intron. We have earlier shown that AP-2beta genotype is associated with serotonergic phenotypes and that brainstem levels of AP-2beta correlate positively to serotonin metabolism in rat frontal cortex. The aim of this study was to investigate the relationship between PMDD and transcription factor AP-2beta genotype. The participants included 176 women with PMDD and 91 healthy controls. Genotyping was performed by polymerase chain reactions. We did not observe any differences in AP-2beta genotype frequencies between PMDD subjects and controls. Our results suggest that AP-2beta genotype is not a risk factor for PMDD. To our knowledge, this is the first study investigating transcription factor AP-2beta genotype in women with PMDD. Hence, these results should be considered preliminary until replicated.

Adolescent↗

PubMed2004

Conditions for noncollinear instabilities of ferromagnetic materials.

Two criteria have been identified here which determine whether a magnetic metal orders in a collinear (e.g., ferromagnet) or noncollinear (e.g., spin-spiral) arrangement. These criteria involve the ratio between the strength of the exchange interaction and the width of the electron bands, as well as Fermi-surface nesting between spin-up and spin-down sheets of the Fermi surface. Based on our analysis we predict that even typical ferromagnetic materials (e.g., Fe, Co, and Ni) should be possible to stabilize in a noncollinear magnetic order in, e.g., high pressure experiments.

Journal Article↗

PubMed2004

Giant magnetic anisotropy in tetragonal FeCo alloys.

In order to further increase the recording density in hard disk drives, new media materials are required. Two essential parameters of future recording media are a large uniaxial magnetic anisotropy energy (MAE) K(u) and a large saturation magnetization M(s). Based on first-principles theory, we predict that very specific structural distortions of FeCo alloys possess these desired properties. The discovered alloy has a saturation magnetization that is about 50% larger than that of FePt--a compound that has received considerable attention lately-with a uniaxial MAE that can easily be tailored reaching a maximum value that is 50% larger than that of FePt.

Journal Article↗

PubMed2004

Alginate impressions for fixed prosthodontics. A 20 year follow up study.

The aim of this study was to estimate whether the survival ratios after 20 years of fixed prosthodontics made of alginate impressions was higher, equivalent or lower, compared to the survival ratios, shown in studies, where different impression materials were used. 151 females and 104 males were screened regarding the condition and age of the restorations at the annual check-up in one of the author's surgeries. Average ages were 55 and 54 years respectively, when the fixed prosthodontics were seated. A total of 1.271 units were produced during the twenty years, 911 abutment teeth and 360 pontics. The type of prosthetic work was divided into three groups: 1) larger fixed prosthodontics 6-14 units (469), 2) smaller fixed prosthodontics 2-5 units (541) and 3) single crowns (261). The results show that alginate impressions can produce fixed prosthodontics with survival ratios similar to those presented in other studies, after 5 years (99%), 1o years (93-96%) and 15 years (74-96%). After 20 years the survival ratio was 61-63%. In conclusion, fixed prosthodontics made according to the syringe-tray alginate impression method may have the same success rates after 20 years compared to that of fixed prosthodontics presented in previous longitudinal clinical studies where other impression materials had been used. In this study, caries and root fractures were the main reasons for removing abutment teeth and pontics.

Adult↗

PubMed2002

Uniaxial magnetocrystalline anisotropy of metal/semiconductor interfaces: Fe/ZnSe(001).

A theoretical study of the magnetic moments and the in-plane magnetic anisotropy of an interface between a cubic ferromagnet and a cubic semiconductor, Fe/ZnSe(001), is presented. Theory confirms the observed, much debated, uniaxial anisotropy of the iron film. This result is important since the calculations are for perfect interfaces with squarelike environments, proving that the fourfolded symmetry of the interface Fe atoms is broken beyond the nearest neighboring semiconducting layer, effects that are usually assumed small. It is demonstrated how the uniaxial anisotropy is produced by the directional covalent bonds at the interface, even without atomic relaxations.

Journal Article↗

PubMed2002

Knowledge of osteoporosis in a Swedish municipality--a prospective study.

BACKGROUND: As a part of the Vadstena Osteoporosis Prevention Project, the knowledge of osteoporosis was examined before the intervention program started, after 5 and 10 years. METHODS: At baseline (in 1989) 15% of the population in two Swedish municipalities was randomly invited to the study. The participants in the study group were invited for examination by forearm bone densitometry and a questionnaire concerning lifestyle and risk factors for osteoporosis and also knowledge of osteoporosis, while the subjects in the control group were examined only by questionnaire. Follow-ups were made in 1994 and in 1999. Meanwhile education about osteoporosis was given to the study group, to the public, and to various professionals in the study community. RESULTS: There was a difference in the level of knowledge between the groups prior to the intervention. The rate of increment did not differ significantly between the groups for the study period. Previous participants had 0.58 higher score than new participants in the study group in 1994 (P = 0.031) and 0.76 higher score in 1999 (P < 0.001) regarding the total number of correct answers. The women in the study group had 0.63 higher score than the men in 1994 (P = 0.016) and 1.03 higher score in 1999 (P < 0.001) regarding the total number of correct answers. CONCLUSION: There was no significant effect of a general intervention program concerning the knowledge of osteoporosis in participants in the intervention area compared to the control area.

Absorptiometry, Photon↗