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Biomedical subjects

S Andersson

Publications and source records attributed to S Andersson.

At least 37 records · Page 2Linked to original sources

Infrared spectroscopy of physisorbed and chemisorbed O2 on Pt(111).

The adsorption of O2 on the Pt(111) surface, with particular emphasis on the influence of substrate temperature, has been studied by infrared reflection absorption spectroscopy (IRAS). In the temperature range 30-90 K the IRAS spectra reveal three different molecular adsorption states. A physisorbed state appears below 40 K while chemisorbed peroxo- and superoxo-like states are observed in the whole temperature range, the characteristic vibrational frequencies are at full coverages of 16O2, 1543 cm(-1) and around 700 cm(-1) and 870 cm(-1), respectively. Flash heating from 30 K to 45 K reveal that the physisorbed state acts as a precursor to the superoxo chemisorption. Theoretical calculations suggest that peroxo molecules may occupy both fcc and hcp threefold sites on the Pt(111) surface. However, within the high resolution of the IRAS measurements we only observe one peroxo state in the temperature range 45-90 K, assigned to occupy the fcc site. The peroxo adsorption probability is significantly lower at 45 K than at 90 K, presumably due to reduced thermal activation from the physisorbed precursor state. A longer lifetime in this precursor state at the low temperature results in formation of larger superoxo islands already at low oxygen coverage.

Journal Article↗

Sudden cardiac death in the young in Sweden: electrocardiogram in relation to forensic diagnosis.

OBJECTIVES: To study electrocardiogram (ECG) in relation to forensic diagnosis in young persons who suffered a sudden cardiac death (SCD) in Sweden during 1992-99. DESIGN: A register study of a national database of forensic medicine in Sweden, selecting all cases of SCD 15-35 years of age. In this group, 12-lead ECGs and clinical data were searched for in military conscription and medical records. The ECGs were re-analysed and classified according to the Minnesota code criteria. SETTING: The whole nation of Sweden. SUBJECTS: Sudden cardiac death victims (66 individuals), 15-35 years of age, where it was possible to obtain an ECG recording. RESULTS: We observed major or minor ECG abnormalities in 82% of the subjects. The most common changes were T wave abnormalities (35%), ST segment changes (32%) and conduction defects (20%). The ECGs were evaluated as pathological in 50% of the cases, more often in arrhythmogenic right ventricular cardiomyopathy (88%) and hypertrophic cardiomyopathy (82%). Cardiac-related symptoms were seen in 76% of the total group and there was a family history of a similar cardiac condition in 18%. CONCLUSIONS: Pathological ECGs were common in young SCD victims, in spite of being taken many years before death. An ECG could help identify prospective victims of SCD, and should always be taken in cases with possible cardiac-related symptoms or a family history of SCD. The pathological ECGs were often found in connection with routine screening at military enlistment for men, which raises the question of a routine screening in the young, including women.

Adolescent↗

A simple automatized audit system for following and managing practices of platelet and plasma transfusions in a neonatal intensive care unit.

During neonatal intensive care, blood components are often used in clinical situations where both their efficacy and safety lack solid justification. A practical system to continuously analyse actual transfusion practices is a prerequisite for improvements of quality in transfusion therapy. We hypothesized that such a system would reveal inappropriate variations in clinical decision making and offer a means for staff education and quality improvement and assurance. The study consisted of three 120-152-day periods (P I, P II and P III) between January 2000 and October 2001 and involved 543 new patient admissions (141 patients with birth weight < 1501 g) and 6227 days of patient care at a single tertiary level NICU. P I was a control with no intervention, P II was after technically introducing the computer system and, the last period, P III was after presenting and discussing the results of P I and P II at a staff meeting. Upon an order of platelet or fresh frozen plasma (FFP) unit from the blood bank, a computer-based audit system compared the last platelet count or prothrombin time [expressed as percentage of normal clotting activity, prothrombin time (PT-%)] to predefined criteria. In the case of exceeding the preset thresholds, the system required additional information and recorded the pretransfusion laboratory values for later analysis. Thirty-two per cent of platelet transfusions were given with pretransfusion platelet count >49 x 10(9) L(-1), and 60% of these transfusions (19% of all platelet transfusions) could not be clinically justified in retrospective chart review. There was no significant change in this practice from P II to P III. FFP transfusions were given with significantly different pretransfusion PT-% values during P II and P III. The proportions of FFP transfusions with pretransfusion PT-% > 49% were 7.8% and 0.9% during P II and P III, respectively (P < 0.0001). In chart review, none of the FFP transfusions with pretransfusion PT-% > 49% could be justified by clinical grounds. Inappropriate transfusions of both platelets and plasma remain a significant challenge for quality assurance of neonatal intensive care. Automated recording of pretransfusion platelet count and prothrombin time reliably identified the poorly justified transfusions and thus offered a practical resource-saving tool for quality assurance of transfusion in the NICU. A significant shift towards more appropriate use of plasma was demonstrated after implementation of the audit system.

Automation↗

Effects of egg yolk testosterone on growth and immunity in a precocial bird.

In oviparous vertebrates, maternal steroid allocation to eggs can have important fitness consequences for the offspring. However, elevated testosterone levels are not only associated with beneficial postnatal effects, such as enhanced growth and high social status, but may also entail costs by suppressing the immune system. In this study, testosterone levels in eggs of Chinese painted quail (Coturnix chinensis) were experimentally manipulated to evaluate its effects on growth and immunocompetence. Testosterone did not affect embryonic development, body size or growth during the first 20 days. However, elevated testosterone levels during embryonic development were immunosuppressive for chicks with inherently higher growth rate. Adaptive scenarios where only beneficial effects of increased testosterone levels are considered may therefore need to be re-evaluated.

Analysis of Variance↗

Relevance of a combined HIV antigen/antibody assay to detect early HIV infections in a low prevalence population: case reports.

The AxSYM HIV Ag/Ab Combo assay (Abbott) has proven to possess excellent sensitivity on seroconversion samples. Since its introduction in Sweden and Norway approximately one year ago, eight cases of acute HIV infections were found earlier compared to assays detecting only antibodies either to screen or to confirm an HIV infection. Data of the presented cases indicate that the early detection of primary HIV infection is of benefit to the individual patient and may reduce further spread of the disease. The impact of HIV combo assays on screening and diagnosis in a low prevalence population is discussed.

AIDS Serodiagnosis↗

Correlations between ultraviolet coloration, overwinter survival and offspring sex ratio in the blue tit.

We studied the correlations between offspring sex ratio, UV coloration and overwinter survival in a population of blue tits, breeding in Gotland, Sweden, over three consecutive breeding seasons. In 2 of 3 years, we found that females paired to males with relatively brighter UV-coloration produced a greater proportion of sons in their broods, and that this effect was significant with all 3 years combined, despite a significant year by male UV interaction. In addition, we found other correlates of sex ratio (breeding time, female age and clutch size) in some, but not all years, and some of these showed significantly different relationships with sex ratio between years. In both years for which data were available, there were indications that males with relatively brighter UV coloration, and that paired with females that produced male-biased clutches, were more likely to survive to the next year. In addition, we also found that in both males and females, individuals produced similar sex ratios in consecutive years. Because correlations with the sex ratio may be expected to be weak, variation in results between years within the same population may be explained by low statistical power or genuine biological differences. Our results suggest that conclusions about sex ratio variation in birds should be based on multiple years. The correlations that we found in some years of this study are consistent with models of adaptive sex ratio adjustment in response to mate quality. However, careful experimental work is required to provide tests of the assumptions of these models, and should be a priority for future work.

Adaptation, Physiological↗

Not 15 but 50% of smokers develop COPD?--Report from the Obstructive Lung Disease in Northern Sweden Studies.

BACKGROUND: The prevalence of chronic obstructive pulmonary disease (COPD) according to guidelines of today seems considerably higher than has been reported also in recent literature. AIM: To estimate the prevalence of COPD as defined by British Thoracic Society (BTS) criteria and the recent global initiative for chronic obstructive lung disease (GOLD) criteria. Further aims were to assess the proportion of underdiagnosis and of symptoms in subjects with COPD, and to study risk factors for COPD. METHODS: In 1996, 5892 of the Obstructive Lung Disease in Northern Sweden (OLIN) Study's first cohort could be traced to a third follow-up survey, and 5189 completed responses (88%) were received corresponding to 79% of the original cohort from December 1985. Of the responders, a random sample of 1500 subjects were invited to a structured interview and a lung function test, and 1237 of the invited completed a lung function test with acceptable quality. RESULTS: In ages >45 years, the prevalence of COPD according to the BTS guidelines was 8%, while it was 14% according to the GOLD criteria. The absolutely dominating risk factors were increasing age and smoking, and approximately a half of elderly smokers fulfilled the criteria for COPD according to both the BTS and the GOLD criteria. Family history of obstructive airway disease was also a risk factor, while gender was not. Of those fulfilling the BTS criteria for COPD, 94% were symptomatics, 69% had chronic productive cough, but only 31% had prior to the study been diagnosed as having either chronic bronchitis, emphysema, or COPD. The corresponding figures for COPD according GOLD were 88, 51, and 18%. CONCLUSIONS: In ages >45 years, the prevalence of COPD according to the BTS guidelines was 8%, and it was 14% according to the GOLD criteria. Fifty percent of elderly smokers had developed COPD. The large majority of subjects having COPD were symptomatic, while the proportion of those diagnosed as having COPD or similar diagnoses was small.

Aged↗

Uses of pH electrodes in nuclear chemistry.

The determination and definition of pH is a controversial subject in many areas in chemistry. For these reasons the International Union of Pure and Applied Chemistry (IUPAC) has developed recommendations for pH measurement. These recommendations are currently (winter 2001) under revision - there will be increased emphasis on traceability of uncertainties in pH measurement. Here we describe how glass electrodes designed for measurement of pH are used in nuclear chemistry. The use of pH electrodes is then related to the IUPAC recommendations. In applied chemistry, e.g. nuclear chemistry, a pH is not sought as often as a hydrogen ion concentration or a simple equilibrium point during a titration. Ionic strengths are, moreover, often above the range in which the IUPAC recommendations apply. In these instances uncertainties must be assessed individually.

Journal Article↗

DC-EEG discloses prominent, very slow activity patterns during sleep in preterm infants.

OBJECTIVES: The objective of this study is to test the hypothesis that the immature human brain exhibits slow electrical activity that is not detected by conventional (i.e. high-pass filtered) electroencephalography (EEG). METHODS: Six healthy preterm infants (conceptional age 33-37 weeks) were recorded bedside with direct current (DC) EEG during sleep. Epochs with quiet sleep were selected to study the delta frequency bursts during discontinuous EEG patterns (trace discontinu or trace alternant), and we compared the waveforms obtained without filtering (i.e. genuine DC-EEG) to those seen after high pass filtering of the same traces. RESULTS: In all infants, DC-EEG demonstrated that the typical delta frequency bursts are consistently embedded in very large amplitude (200-700 microV) and long lasting (1-5s) occipitally negative transients, which are not seen in conventional EEG. CONCLUSIONS AND SIGNIFICANCE: Our study demonstrates that (i) the most prominent spontaneous EEG activity of a sleeping preterm infant consists of very slow, large amplitude transients, and (ii) the most salient features of these transients are not seen in conventional EEG. Proper recording of this type of brain activity by DC-EEG provides a novel way for non-invasive assessment of neonatal brain function.

Brain↗

Characterization of the bone-resorptive effect of interleukin-11 in cultured mouse calvarial bones.

Interleukin-11 (IL-11) is a stromal cell-derived cytokine that can enhance osteoclast formation and stimulate bone resorption. In the present study, the characteristics of the resorptive effect of IL-11 in mouse calvarial bones were investigated. Both recombinant mouse IL-11 and human IL-11 caused concentration- and time-dependent stimulations of (45)Ca release from prelabeled mouse calvariae. Half-maximal responses were obtained at 0.7 ng/mL (approximately 40 pmol/L). Mouse and human IL-11 also stimulated release of (3)H from [(3)H]-proline-labeled bones. The magnitude of the (45)Ca and (3)H release (1.4-1.6-fold) caused by a maximally effective concentration of IL-11 was less than the stimulation (2.5-4.0-fold) elicited by a maximum concentration of parathyroid hormone (PTH). Release of (45)Ca by IL-11 was unaffected by the mitotic inhibitors, hydroxyurea and aphidicolin. In addition to resorption of bone, IL-11 caused a small (1.5-2.0-fold) enhancement of prostaglandin E(2) (PGE(2)) biosynthesis in calvariae, but had no effect on the mRNA expression of cyclooxygenase-1 and -2, or cytosolic phospholipase A(2). Indomethacin and flurbiprofen abolished the formation of PGE(2) and partially reduced (45)Ca release stimulated by IL-11. When either mouse interleukin-4 (IL-4) or interleukin-13 (IL-13) was added to calvariae treated with IL-11, (45)Ca release was inhibited. Resorption caused by IL-11 was also inhibited by both anti-mouse glycoprotein 130 (gp130) and an antibody neutralizing IL-11, but these agents had no effect on (45)Ca release caused by PTH or 1,25(OH)(2)vitamin D(3) (D(3)). Real-time, quantitative polymerase chain reaction (PCR) analysis (TaqMan PCR) and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) demonstrated that IL-11 caused concentration-dependent enhancements of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) mRNA, without affecting the mRNA expression of RANK. Mouse RANKL stimulated (45)Ca release in the calvarial bones. The stimulatory effects of RANKL and IL-11 were inhibited by mouse OPG. These data demonstrate that IL-11 stimulates osteoclastic resorption in mouse calvariae by mechanisms that are independent of cell proliferation; partially dependent on prostaglandin biosynthesis; sensitive to inhibition by IL-4, IL-13, and OPG; and associated with enhanced expression of RANKL and OPG. In addition, IL-11 was not found to play an essential role in resorption stimulated by other calciotropic agents in calvariae.

Animals↗

Developmental stability in Brassica cretica: the effect of crossing distance on fluctuating asymmetry in cotyledon morphology.

In the present investigation of Brassica cretica, a wild relative of the cultivated cabbage, B. oleracea, we performed an extensive crossing experiment, involving self-pollinations, random outcrosses within populations and hybridizations between populations or species, to evaluate the relationship between crossing distance and developmental stability, estimated as the absolute difference between the right and left lobe of the cotyledons. The frequency distribution of the right-minus-left scores had a narrower peak than expected for normally-distributed data, but there was no directional asymmetry or antisymmetry. Despite evidence for inbreeding depression in seedling biomass and cotyledon size, the type of cross had negligible influence on cotyledon asymmetry. Separate analyses of between-population hybrids revealed differences among progenies from different pairs of populations and a tendency for the F1 hybrid means to decrease with the geographic distance separating the parent populations, but only for the two size variables. Based on these and other observations, we propose that the degree of cotyledon asymmetry is unrelated to genome-wide characteristics, such as the level of heterozygosity and genomic co-adaptation, and that cotyledon asymmetry is unrelated to the level of genetic stress experienced by each individual. Hence, there is no reason to consider measures of asymmetry as more sensitive indicators of genetic health than conventional fitness variables.

Analysis of Variance↗

Gastric emptying in myotonic dystrophy.

BACKGROUND: Gastrointestinal symptoms are common and important for the quality of life in patients with myotonic dystrophy (MD). Gastric emptying was studied in patients with MD who suffered from symptoms suggesting slow gastric emptying and the effect of prokinetic treatment was evaluated. METHODS: Gastric emptying was studied in 10 patients with MD who were suffering from nausea, early satiety, bloating, regurgitation, vomiting, or abdominal pain using a (99)Tc-labelled test meal, and was compared with gastric emptying in a group of healthy controls. The patients were subsequently treated with erythromycin and their gastrointestinal symptoms were recorded and the gastric emptying test was repeated. RESULTS: Patients with MD had a significantly longer gastric lag phase (46.1 +/- 4.3 vs. 31.9 +/- 4.0 min, P = 0.03), a slower emptying phase (7.1 +/- 0.9 vs. 10.2 +/- 0.9 kJ min(-1), P = 0.02) and a longer half-emptying time, T50 (141.7 +/- 10.5 vs. 98.6 +/- 8.7 min, P = 0.01) than a matched control group. Erythromycin did not stimulate the gastric emptying rate. The effect on gastrointestinal symptoms was modest, except for a reduction of diarrhoea. CONCLUSIONS: Patients with MD suffering from nausea, vomiting and early satiety, displayed a slow gastric emptying. Treatment with erythromycin had only moderate effect on gastric emptying or gastric symptoms, but reduced diarrhoea in a majority of the patients.

Adult↗

The aphasic person's views of the encounter with other people: a grounded theory analysis.

Being affected by aphasia influences the total life experience. The aim of this study was to generate a theoretical model, from a nursing perspective, of what aphasic persons (n = 12) experience in encounters with other people. Data were collected through interviews which adopted a biophysical, socio-cultural and psychological approach and then analysed using grounded theory method. Two main categories emerged, namely: 'interaction' and 'support'. Encountered experiences led to: 'a feeling of having ability'; 'a feeling of being an outsider'; and 'a feeling of dejection or uncertainty'. The feeling state was dependent on whether the interaction was 'obstructed' or 'secure' and on whether the support resulted in 'strengthened' or 'impaired' self-esteem. Therefore nurses need to give support that enhances patients' self-esteem and which results in them gaining a positive and realistic view of their aphasia, as well as involving those around them in this perspective. This then will give the possibility for the patient to turn the interaction process from an obstructed into a secure one.

Adaptation, Psychological↗

Early dexamethasone decreases expression of activation markers on neutrophils and monocytes in preterm infants.

AIM: To investigate the effects of early dexamethasone administration on activation of circulating neutrophils and monocytes in preterm infants with respiratory distress syndrome requiring treatment with surfactant. METHODS: Neonates (n = 30) with respiratory distress were randomized to receive dexamethasone (DEX group, 29.1 +/- 1.2 wk, 1223 +/- 156 g, n = 15) from the first postnatal day, or to serve as controls (control group, 29.2 +/- 1.4 wk, 1250 +/- 148 g, n = 15). Dexamethasone was given as a 4 d course (0.5 mg kg(-1) on postnatal days 1 and 2, and 0.25 mg kg(-1) on days 3 and 4). Polymorphonuclear leucocyte (PMN) and monocyte surface expression of CD11b, L-selectin and CD14 was quantified with flow cytometry, and plasma macrophage-inflammatory protein-1alpha (MIP-1alpha) with an enzyme-linked immunosorbent assay. Blood samples were collected on days 1, 2-3 and 5-7. RESULTS: In the DEX group 1/15, and in the control group 7/15 developed bronchopulmonary dysplasia (p < 0.04). PMN CD11b (median 100, range 70-190 vs 154, 96-213, p=0.01), monocyte CD14 (235, 102-433 vs 355, 219-533, p=0.01) and plasma MIP-1alpha (20 ng l(-1), 20-32 vs 37 ng l(-1), 20-70, p = 0.005) were lower in the DEX group at days 2-3. All adhesion molecule expression and plasma MIP-1alpha levels were comparable at days 5-7, with the exception of monocyte L-selectin expression levels, which remained lower in the DEX group. CONCLUSION: In preterm infants with respiratory distress syndrome, early dexamethasone causes downregulation of PMN and monocyte activation. This may attenuate pulmonary inflammation and improve pulmonary outcome.

Anti-Inflammatory Agents↗

Pulmonary vascular endothelial growth factor and Flt-1 in fetuses, in acute and chronic lung disease, and in persistent pulmonary hypertension of the newborn.

Respiratory distress syndrome (RDS) and development of bronchopulmonary dysplasia (BPD) are characterized by endothelial cell damage. Persistent pulmonary hypertension of the newborn (PPHN) is a disorder that alters the pulmonary microvasculature. Immunohistochemistry for VEGFA(165), an endothelial cell mitogen, and its receptor Flt-1, was performed on lung tissues from autopsies from four fetuses, three preterm infants, four term infants without primary lung disease, four infants with BPD, and four infants with PPHN. VEGF was measured in tracheal aspirates from 31 preterm infants, 5 intubated term infants without primary lung injury, and 12 infants with PPHN during the first 10 postnatal days, and from 8 infants with BPD. Immunohistochemistry for VEGF and Flt-1 was similar in fetuses, preterm infants, and term infants: for VEGF mostly in bronchial epithelium and alveolar macrophages, and for Flt-1 mostly in vascular endothelial cells and bronchial epithelial cells. In patients with BPD, and PPHN, staining for VEGF and Flt-1 appeared also in Type II pneumocytes. Preterm infants with more severe RDS had lower VEGF than those who recovered. The persistent expression of VEGF and Flt-1 during the fetal and neonatal period supports a physiological role for VEGF in human lung development. The lower pulmonary VEGF in preterm infants with more severe RDS may contribute to the pathophysiology of the acute lung injury. In BPD, the expression of VEGF in alveolar epithelium may represent a compensatory increase after the acute phase of the lung disease. In PPHN, that more cell types express VEGF and Flt-1, and the tendency toward a higher concentration of pulmonary VEGF may represent enhanced production of VEGF in response to impaired endothelial function.

Acute Disease↗

Pooling of samples for seroepidemiological surveillance of human T-cell lymphotropic virus types I and II.

We evaluated a straight forward pooling strategy for antibody screening of HTLV-I/II, using panels of sera from various parts of the world including a total of 43 HTLV-I and 54 HTLV-II positive specimens. Four antibody screening assays were included in the evaluation: the HTLV-I/II GE 80/81 (Murex Diagnostics), the HTLV-I/HTLV-II Ab Capture ELISA (Ortho Diagnostics), the HTLV-I/II ELISA 3.0 (Genelabs Diagnostics) and the Serodia HTLV-I (Fujirebio). The Murex and Ortho assays represent a new generation of HTLV screening tests with a sandwich format incorporating both HTLV-I and HTLV-II synthetic and/or recombinant peptide antigens. The Genelabs assay is an indirect ELISA with recombinant HTLV-I and -II antigens and Serodia is a particle agglutination assay with HTLV-I whole viral lysate. Each HTLV-positive sample was included in pools of 1/1 up to 1/16, in two-fold steps made in normal HTLV-negative blood donor serum from one up to nine donors. For HTLV-I, with the exception of one false negative sample in dilution 1/16 with Genelabs ELISA, all assays were positive at all dilutions. The Murex assay had absorbance values at maximum levels for all samples at all dilutions. The other assays had gradually decreasing absorbance values although clearly above cut-off. For HTLV-II, the Murex assay correctly detected all samples to dilution 1/16 despite gradually decreasing signals. The Serodia assay had 100% sensitivity to dilution 1/4 while at 1/8 and 1/16 it decreased 82 and 80%, respectively. The Genelabs ELISA had gradually decreasing sensitivity for HTLV-II from 98 (1/1) to 33% (1/16) while the Ortho assay detected all specimens at all dilutions in a limited set of samples tested. Taken together, this evaluation has shown that pooling of samples may be an appropriate strategy for serosurveillance of HTLV. It is, however, crucial to limit the number of samples and to choose assays that allow the dilution caused by the pooling. Using the best performing assays in this evaluation for pools of e.g. five samples would leave a reasonable safety margin.

Agglutination Tests↗

The significance of p53 codon 72 polymorphism for the development of cervical adenocarcinomas.

Infection with the human papillomavirus is an important co-factor in the development of cervical carcinomas. Accordingly, HPV DNA is recognised in most of these tumours. Polymorphism of the p53 gene, codon 72, is also considered a risk factor in the development of cervical carcinoma. However, this finding is contradicted by several observers. In the present investigation, 111 cases of adenocarcinoma of the cervix collected through the Swedish Cancer Registry and 188 controls (females with normal cytology at organised gynaecological screening) were analysed with regard to p53, codon 72, polymorphism using a PCR- and SSCP-based technique. In the controls, 9% showed pro/pro, 44% pro/arg and 47% arg/arg, whereas in the invasive adenocarcinomas, the corresponding figures were 0%, 29% and 71%, respectively. The difference was statistically significant (P = 0.001). HPV DNA was identified in 86 tumours (HPV 18 in 48, HPV 16 in 31 and HPV of unknown type in 7 cases) and 25 tumours were HPV negative. The p53, codon 72, genotypes observed in HPV-positive and HPV-negative cervical adenocarcinomas were not statistically different (P = 0.690). The results indicate that women homozygotic for arg/arg in codon 72 of the p53 gene are at an increased risk for the development of cervical adenocarcinomas. However, this genetic disposition seems to be unrelated to the HPV infection.

Adenocarcinoma↗