| 1. |
- Ahola, T., et al.
(författare)
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Plasma 8-isoprostane is increased in preterm infants who develop bronchopulmonary dysplasia or periventricular leukomalacia
- 2004
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Ingår i: Pediatr Res. - 0031-3998. ; 56:1, s. 88-93
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Tidskriftsartikel (refereegranskat)abstract
- Our aim was to assess the plasma free 8-epi-prostaglandin F(2alpha) (8-isoprostane) and ascorbyl radical as risk indicators for oxidative damage in extremely low birth weight infants (ELBWIs) and the effect of N-acetylcysteine (NAC) on these markers. Plasma samples were collected on days 3 and 7 of life from infants who were enrolled in a randomized, controlled trial in which i.v. NAC or placebo was administered to ELBWIs during the first week of life, with the aim of preventing bronchopulmonary dysplasia (BPD). Plasma 8-isoprostane was analyzed in 83 infants using an enzyme immunoassay kit. Ascorbyl radical concentration was measured in 61 infants with electron spin resonance spectroscopy. The 8-isoprostane concentrations were similar in the NAC and placebo groups. In infants who later developed BPD or died (n = 29), the median (range) 8-isoprostane concentration was significantly higher (p = 0.001) on day 3 and day 7 [50.0 pg/mL (19-360) and 57.0 pg/mL (14-460), respectively] than in survivors without BPD [n = 54; 34.5 pg/mL (5-240) and 39.5 pg/mL (7-400), respectively]. The 8-isoprostane levels increased significantly more (p < 0.05) in infants who later developed periventricular leukomalacia. NAC treatment or the later development of BPD was not related to the ascorbyl radical levels. The ascorbyl radical level decreased significantly in all groups from day 3 to day 7, but the difference between the groups was not significant. The mean (SD) ascorbyl radical level on day 3 was significantly higher (p < 0.01) in infants who later developed periventricular leukomalacia [287 (124) versus 194 (90)]. These data suggest that plasma 8-isoprostane could serve as a marker in assessing the risk for BPD development in ELBWIs.
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| 2. |
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| 3. |
- Amer-Wåhlin, I, et al.
(författare)
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Swedish randomized controlled trial of cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram revisited : analysis of data according to standard versus modified intention-to-treat principle.
- 2011
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : John Wiley & Sons Ltd.. - 0001-6349 .- 1600-0412. ; 90:9, s. 990-996
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To undertake a renewed analysis of data from the previously published Swedish randomized controlled trial on intrapartum fetal monitoring with cardiotocography (CTG-only) vs. CTG plus ST analysis of fetal electrocardiogram (CTG+ST), using current standards of intention-to-treat (ITT) analysis and to compare the results with those of the modified ITT (mITT) and per protocol analyses. METHODS: Renewed extraction of data from the original database including all cases randomized according to primary case allocation (n=5 049). MAIN OUTCOME MEASURE: Metabolic acidosis in umbilical artery at birth (pH <7.05, base deficit in extracellular fluid >12.0 mmol/l) including samples of umbilical vein blood or neonatal blood if umbilical artery blood was missing. RESULTS: The metabolic acidosis rates were 0.66% (17 of 2 565) and 1.33% (33 of 2 484) in the CTG+ST and CTG-only groups, respectively [relative risk (RR) 0.50; 95% confidence interval (CI) 0.28-0.88; p=0.019]. The original mITT gave RR 0.47, 95%CI 0.25-0.86 (p=0.015), mITT with correction for 10 previously misclassified cases RR 0.48, 95%CI 0.24-0.96 (p=0.038) and per protocol analysis RR 0.40, 95%CI 0.20-0.80 (p=0.009). The level of significance of the difference in metabolic acidosis rates between the two groups remained unchanged in all analyses. CONCLUSION: Re-analysis of data according to the ITT principle showed that regardless of the method of analysis, the Swedish randomized controlled trial maintained its ability to demonstrate a significant reduction in metabolic acidosis rate when using CTG+ST analysis for fetal surveillance in labor.
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| 4. |
- Amu, Sylvie, 1978, et al.
(författare)
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Cytokines in the placenta of Pakistani newborns with and without intrauterine growth retardation
- 2006
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Ingår i: Pediatr Res. ; 59:2, s. 254-8
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Tidskriftsartikel (refereegranskat)abstract
- Although intrauterine growth retardation (IUGR) is a major risk factor for increased neonatal mortality and morbidity, the mechanisms behind it are not clear. We analyzed cytokine gene expression and gene polymorphisms in infants with and without IUGR in Pakistan, where IUGR is very common. 45 IUGR and 55 control mother/infant pairs were studied. mRNA for IL-10, IL-8, TNF-alpha, TGF-beta, IL-6, IL-4, IL-1beta, IL-12, IFN-gamma and GAPDH was quantified with RT-PCR from placenta. Cytokine and cytokine receptor gene polymorphisms for -1087IL10, -308TNFA, -174IL6, +915TGFB1, intron 2 IL1RN, +36TNFR1, 150V IL4RA and -159CD14 were determined from genomic DNA. The serum levels of IL-1beta, IL-6, IL-8, IL-10, IL-12, TNF-alpha and TGF-beta were measured. There was a significant decrease of IL-10 and IL-12, but increase of TGF-beta in the decidua and similarly decrease of IL-10, but increase of TGF-beta in the trophoblasts of the IUGR placentas compared with the non-IUGR placentas. We found significantly lower levels of IL-1beta in serum from the mothers of the IUGR infants and of TGF-beta in serum of the infants with IUGR compared with the non-IUGR infants. We note that the IL-10 mRNA expression in the decidua was down-regulated, but the TGF-beta mRNA up-regulated in IUGR placentas of mothers from a population with multiple risk factors for IUGR. We propose that the low IL-10 in the placenta may be involved in the pathogenesis of IUGR and might possibly be treatable.
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| 5. |
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| 6. |
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| 7. |
- Blad, Sofia, et al.
(författare)
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ECG and heart rate variability changes in preterm and near-term fetal lamb following LPS exposure.
- 2008
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Ingår i: Reproductive sciences (Thousand Oaks, Calif.). - : Springer Science and Business Media LLC. - 1933-7205 .- 1933-7191. ; 15:6, s. 572-83
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to evaluate the myocardial response in the preterm and near-term fetal lamb with infection. Chronically instrumented fetal lambs were exposed to lipopolysaccharide (LPS), and the fetal electrocardiogram (FECG) ST waveform was examined using STAN. Fetal heart rate variability (FHRV) was automatically analyzed by adapting a polynomial function to the RR sequence in the FECG. Preterm fetuses exposed to >90 ng/kg LPS died within 8 hours of LPS administration, a response not seen in near-term fetuses. In both surviving and nonsurviving preterm fetuses, cardiovascular responses were characterized by decreased arterial pressure, negative T waves, and tachycardia accompanied by an increase in FHRV. Similar changes were not observed in the near-term fetuses after LPS. The study shows that preterm lambs are more sensitive to LPS in terms of myocardial/cardiovascular response than the more mature fetuses are. High FHRV and negative ST waveform seem to characterize the LPS-induced stress response in preterm fetuses.
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| 8. |
- Dean, Justin M, et al.
(författare)
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Cerebellar white matter injury following systemic endotoxemia in preterm fetal sheep.
- 2009
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Ingår i: Neuroscience. - : Elsevier BV. - 1873-7544 .- 0306-4522. ; 160:3, s. 606-15
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Tidskriftsartikel (refereegranskat)abstract
- Injury to the cerebellum and brainstem is becoming increasingly recognized in prematurely born infants. The role of infection/inflammation in mediating damage to those structures in the preterm brain is largely unknown. Preterm fetal sheep (70% gestation) received either saline-vehicle (control group; n=11) or Escherichia coli lipopolysaccharide (100 ng intravenous [i.v.]; lipopolysaccharide [LPS] group; n=9), and were allowed to recover for 3 days before sacrifice. A diffuse pattern of cerebellar white matter damage was observed in all animals exposed to LPS, while focal cerebellar white matter lesions were observed in three out of nine animals, and an intragyral white matter hemorrhage in one animal. Cerebellar white matter injury was associated with a statistically significant loss of oligodendrocyte transcription factor-2-positive oligodendrocytes and increased terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cell counts. Ionized calcium binding adapter molecule 1 (Iba1)-positive cells which had the morphology of activated microglia were commonly observed in areas of injury. There was no obvious injury to the cerebellar cortex or to cerebellar Purkinje cells, and no obvious injury in any region of the brainstem. These data provide support for a role of infection/inflammation in selective white matter injury in the immature cerebellum, and demonstrate a differential vulnerability of the brainstem and cerebellar white matter to injury at this time.
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| 9. |
- Dean, Justin M, et al.
(författare)
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Delayed cortical impairment following lipopolysaccharide exposure in preterm fetal sheep.
- 2011
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Ingår i: Annals of neurology. - : Wiley. - 1531-8249 .- 0364-5134. ; 70:5, s. 846-856
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Preterm infants exhibit chronic deficits in white matter (WM) and cortical maturation. Although fetal infection/inflammation may contribute to WM pathology, the factors contributing to cortical changes are largely unknown. We examined the effect of fetal lipopolysaccharide (LPS) exposure on WM and cortical development as assessed by magnetic resonance imaging (MRI), electroencephalography (EEG), and histopathology in fetal sheep at preterm human equivalent age. METHODS: LPS was administered to fetal sheep at 102.5 ± 0.5 days of gestation. Continuous biophysical recordings were analyzed for 10 days after LPS. At postmortem, measurement of cerebral WM and cortical tissue volumes was achieved by stereological techniques. Specific effects of LPS on MRI-assessed T(1) -weighted and T(2) -weighted images, and immunohistochemical expression of oligodendrocytes, proliferating cells, cortical NeuN-positive and Nurr1-positive neurons (subplate marker), and cell death mechanisms were examined. RESULTS: We observed reductions in WM (∼21%; LPS, 1.19 ± 0.04 vs control, 1.51 ± 0.07cm(3) ; p < 0.001) and cortical (∼18%; LPS, 2.34 ± 0.10 vs control, 2.85 ± 0.07cm(3) ; p < 0.001) volumes, associated with overt and diffuse WM injury, T(1) -/T(2) -weighted signal alterations, and reduced numbers of WM oligodendrocytes (LPS, 485 ± 31 vs control, 699 ± 69 cells/mm(2) ; p = 0.0189) and NeuN-positive (LPS, 421 ± 71 vs control 718 ± 92 cells/mm(2) ; p = 0.04) and Nurr1-positive (control, 2.5 ± 0.6 vs LPS, 0.6 ± 0.1 cells/mm(2) ; p = 0.007) cortical neurons after LPS. Moreover, there was loss of the normal maturational increase in cortical EEG amplitude, which correlated with reduced cortical volumes. INTERPRETATION: Fetal exposure to LPS prior to myelination onset can impair both white matter and cortical development in a preclinical large animal model, supporting a role for maternal/fetal infection in the pathogenesis of preterm brain injury. ANN NEUROL 2011.
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| 10. |
- Ellegård, Eva, 1960, et al.
(författare)
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Atresia of the submandibular duct orifices: an unusual cause of feeding problems and failure to thrive in an infant.
- 2010
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Ingår i: Acta paediatrica. - : Wiley. - 1651-2227 .- 0803-5253. ; 99:7, s. 1100-1101
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Atresia of the submandibular duct orifice is a rare developmental anomaly, which causes swelling of the duct by accumulation of saliva. The cystic mass in the floor of the mouth can cause feeding problems, which can be treated by surgical opening of the duct. We report the first Swedish case in a male infant, who had severe difficulties to feed because of bilateral swellings of the submandibular ducts caused by orifice atresia. Conclusion: This is the first case that has described failure to thrive because of this condition and catch up after treatment. It is important to remember that evaluation of feeding problem in an infant must include inspection of the oral cavity.
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| 11. |
- Flisberg, Anders, 1958, et al.
(författare)
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Does indomethacin for closure of patent ductus arteriosus affect cerebral function?
- 2010
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Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 99:10, s. 1493-1497
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To study whether indomethacin used in conventional dose for closure of patent ductus arteriosus affects cerebral function measured by Electroencephalograms (EEG) evaluated by quantitative measures. Study design: Seven premature neonates with haemodynamically significant persistent ductus arteriosus were recruited. EEG were recorded before, during and after an intravenous infusion of 0.2 mg/kg indomethacin over 10 min. The EEG was analysed by two methods with different degrees of complexity for the amount of low-activity periods (LAP, "suppressions") as an indicator of affection of cerebral function. Results: Neither of the two methods identified any change in the amount of LAPs in the EEG as compared to before the indomethacin infusion. Conclusion: Indomethacin in conventional dose for closure of patent ductus arteriosus does not affect cerebral function as evaluated by quantitative EEG.
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| 12. |
- Flisberg, Anders, 1958, et al.
(författare)
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EEG and spectral edge frequency : analysis in posthypoxic newborn piglets
- 2010
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Ingår i: Neuro - endocrinology letters. - : Brain Research Promotion. - 0172-780X. ; 31:2, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the frequency content of the electroencephalogram (EEG) during recovery after a severe hypoxic insult in newborn piglets. METHODS: EEG was continuously monitored in nine newborn piglets exposed to a severe hypoxic period. Power spectra in five frequency bands were calculated using Fourier transformation. Spectral edge frequency 90 (SEF90) was defined as the frequency below which 90% of the power in the EEG was located. The piglets were divided into two groups; Group 1 represented piglets with some EEG recovery and Group 2 represented piglets without any EEG recovery. RESULTS: The recovery of the EEG in Group 1 had the same time course in all frequency bands. SEF90 indicates recovery earlier than the value of total power. But SEF90 also signals activity in the EEGs that were almost completely suppressed. When SEF90 was calculated during periods of periodic EEG activity during the very early phase of recovery, the values fell within the same range as during the control period. CONCLUSION: Spectral analysis of continuous EEG in newborn piglets exposed to very severe hypoxia showed that no specific frequency band of the EEG preceded the other ones during recovery. The results of the SEF90 measure, demonstrates the need for critical analysis of the raw EEG before any reliable estimation of cerebral function can be made.
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| 13. |
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| 14. |
- Hafström, Maria, 1962, et al.
(författare)
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Boys and girls differ in symptoms and neurodevelopmental outcome after perinatal metabolic acidosis, a population-based study
- 2019
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Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253. ; 108:8, s. 1427-1433
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Tidskriftsartikel (refereegranskat)abstract
- Aim To evaluate sex differences in infants born at term with metabolic acidosis with regard to perinatal health and symptomatology, and developmental outcome. Methods From a population-based cohort of infants born at term (n = 14 687), 78 were prospectively identified as having metabolic acidosis at birth. Two matched controls per case were selected. Sex differences in perinatal characteristics and in neurodevelopmental outcome at 6.5 years of age were analysed. Subgroup analysis was made based on need of neonatal care and planned follow-up. Results Acidotic boys who appeared healthy, that is with no need of specialised neonatal care respectively only followed at ordinary health care service, have worse perinatal symptoms and less favourable neurodevelopmental outcome compared to girls. The male disadvantage concerning neurodevelopmental outcome was also indicated in children without acidosis. Outcome at 6.5 years was associated with Apgar at 10 minutes (p = 0.03), need of neonatal care (p = 0.04) and sex (p = 0.02) but not acidosis per se (p = 0.54). Conclusion Sex affected immediate symptomatology in term acidotic infants and neurodevelopmental outcome at the age of 6.5 years. The findings were seen in those who appeared healthy in the neonatal period. The results suggest that sex should be considered in assessment of acidotic children.
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| 15. |
- Hafström, Maria, 1962, et al.
(författare)
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Developmental Outcome at 6.5 Years After Acidosis in Term Newborns : A Population-Based Study
- 2012
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Ingår i: Pediatrics. - : American Academy of Pediatrics. - 0031-4005 .- 1098-4275. ; 129:6, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Infants who develop encephalopathy after perinatal asphyxia have an increased risk of death and adverse neurologic outcome. Conflicting results exist concerning outcome in healthy infants with metabolic acidosis at birth. The aim of the current study was to evaluate whether metabolic acidosis at birth in term infants who appear healthy is associated with long-term developmental abnormalities. METHODS: From a population-based cohort (14 687 deliveries), 78 infants were prospectively identified as having metabolic acidosis (umbilical artery pH , 7.05 and base deficit in the extracellular fluid .12.0 mmol/L). Two matched controls per case were selected. The child health and school health care records were scrutinized for developmental abnormalities. RESULTS: Outcome measures at 6.5 years of age for 227 of 234 children (97%) were obtained. No differences were found concerning neurologic or behavioral problems in need of referral action or neurodevelopmental diagnosis in comparison of control children with acidotic children who had appeared healthy at birth, ie, had not required special neonatal care or had no signs of encephalopathy. CONCLUSIONS: Infants born with cord metabolic acidosis and who appear well do not have an increased risk for neurologic or behavioral problems in need of referral actions or special teaching approaches at the age of 6.5 years. Pediatrics 2012;129:1–7
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| 16. |
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| 17. |
- Hagberg, Henrik, 1955, et al.
(författare)
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Extracellular overflow of glutamate, aspartate, GABA and taurine in the cortex and basal ganglia of fetal lambs during hypoxia-ischemia.
- 1987
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Ingår i: Neuroscience letters. - 0304-3940. ; 78:3, s. 311-7
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Tidskriftsartikel (refereegranskat)abstract
- Extracellular levels of excitatory and inhibitory amino acids were measured in the cortex and striatum of asphyxiated fetal lambs. The fetus was exteriorized from the anesthetized ewe and dialysis probes were placed in the parietal cortex and caudate nucleus. Cerebral blood flow was measured with Xe-clearance. Cortical somatosensory-evoked potentials and electroencephalogram (EEG) were continuously recorded. Asphyxia was induced by clamping the umbilical cord or by graded compression of the maternal aorta. Asphyxia accompanied by elevated cerebral blood flow resulted in a moderate rise in extracellular amino acid levels. During extreme asphyxia, i.e. abolished evoked potentials and reduced cerebral blood flow, marked extracellular elevations of glutamate (3- to 11-fold), aspartate (3- to 7-fold), gamma-aminobutyric acid (GABA) (3- to 5-fold) and taurine (3- to 18-fold) occurred, the higher values representing striatum. Excessive levels of excitatory amino acids may exert injurious effects on immature neurons during such hypoxic-ischemic states.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
- Kjellmer, Ingemar, 1935, et al.
(författare)
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Gunilla Rabo Berglund, 1923–2016
- 2017
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Ingår i: Svensk Medicinhistorisk Tidskrift. ; 21:1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 22. |
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| 23. |
- Kjellmer, Ingemar, 1935, et al.
(författare)
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ST analysis of the fetal electrocardiogram - Comments on recent experimental data
- 2019
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 14:8
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In their paper, Andriessen at al present a validation of fetal ECG analysis and the clinical STAN device in midgestation fetal lambs exposed to 25 minutes of umbilical cord occlusion. The study presents results that contrast remarkably from previously published experimental data which raises a number of questions and comments. The most striking finding of Andriessen et al is the recording of an extremely high number of alarms from the STAN equipment during control conditions when no alarms at all are expected. These patterns have never been seen, neither in the clinical situation nor in our own fetal sheep studies. The reason for this becomes apparent when their way of recording the FECG is scrutinized. In their assessment of STAN, Andriessen at al use an assumed negative aVF lead with the assumption that it will reflect the FECG in the same way as the unipolar scalp lead used clinically. The signal used for disqualification of STAN is itself not qualified to properly represent the fetal scalp lead signal that STAN is designed for. To question a proven technology is fully accepted but those attempting would be asked to argue along fully validated data and related analysis including questioning of their own data.
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| 24. |
- Kjellmer, Ingemar, 1935
(författare)
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The paediatrician--past, present and future--a conversation with Nils Rosén von Rosenstein.
- 2009
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Ingår i: Acta paediatrica (Oslo, Norway : 1992). - : Wiley. - 1651-2227 .- 0803-5253. ; 98:9, s. 1392-9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- An imagined conversation takes place with the author of the first textbook of Paediatrics, Nils Rosén von Rosenstein. Enormous progress in the prevention and treatment of diseases of children is demonstrated. But a different spectrum of diseases has replaced the old one. And in spite of unprecedented material well-being a substantial minority of our children cannot make full use of their capabilities. Conclusion: We must resume the full responsibility for our children and act as their advocates in society.
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| 25. |
- Löfgren, N., et al.
(författare)
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On evaluation of spectrum estimators for EEG
- 2004
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Ingår i: Proceedings Of The 26th Annual International Conference Of The IEEE Engineering In Medicine And Biology Society. - : IEEE. - 0780384393 ; 1, s. 305-9
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Konferensbidrag (refereegranskat)abstract
- In the search for how neonatal EEG is affected by asphyxia it is of importance to find reliable estimates of EEG power spectra. Several spectral estimation methods do exist, but since the true spectra are unknown it is hard to tell how well the estimators perform. Therefore a model to generate simulated EEG with known spectrum is proposed and the model is used to evaluate performance of several parametric and Fourier based spectral estimators.
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| 26. |
- Löfgren, Nils, 1969, et al.
(författare)
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Spectral distance for ARMA models applied to electroencephalogram for early detection of hypoxia
- 2006
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Ingår i: Journal of Neural Engineering. - : IOP Publishing. - 1741-2560 .- 1741-2552. ; 3:3, s. 227-34
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Tidskriftsartikel (refereegranskat)abstract
- A novel measure of spectral distance is presented, which is inspired by the prediction residual parameter presented by Itakura in 1975, but derived from frequency domain data and extended to include autoregressive moving average (ARMA) models. This new algorithm is applied to electroencephalogram (EEG) data from newborn piglets exposed to hypoxia for the purpose of early detection of hypoxia. The performance is evaluated using parameters relevant for potential clinical use, and is found to outperform the Itakura distance, which has proved to be useful for this application. Additionally, we compare the performance with various algorithms previously used for the detection of hypoxia from EEG. Our results based on EEG from newborn piglets show that some detector statistics divert significantly from a reference period less than 2 min after the start of general hypoxia. Among these successful detectors, the proposed spectral distance is the only spectral-based parameter. It therefore appears that spectral changes due to hypoxia are best described by use of an ARMA- model-based spectral estimate, but the drawback of the presented method is high computational effort.
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| 27. |
- Löfhede, Johan, 1978, et al.
(författare)
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Automatic classification of background EEG activity in healthy and sick neonates
- 2010
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Ingår i: Journal of Neural Engineering. - : IOP Publishing. - 1741-2560 .- 1741-2552. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The overall aim of our research is to develop methods for a monitoring system to be used at neonatal intensive care units. When monitoring a baby, a range of different types of background activity needs to be considered. In this work, we have developed a scheme for automatic classification of background EEG activity in newborn babies. EEG from six full-term babies who were displaying a burst suppression pattern while suffering from the after-effects of asphyxia during birth was included along with EEG from 20 full-term healthy newborn babies. The signals from the healthy babies were divided into four behavioural states: active awake, quiet awake, active sleep and quiet sleep. By using a number of features extracted from the EEG together with Fisher’s linear discriminant classifier we have managed to achieve 100% correct classification when separating burst suppression EEG from all four healthy EEG types and 93% true positive classification when separating quiet sleep from the other types. The other three sleep stages could not be classified. When the pathological burst suppression pattern was detected, the analysis was taken one step further and the signal was segmented into burst and suppression, allowing clinically relevant parameters such as suppression length and burst suppression ratio to be calculated. The segmentation of the burst suppression EEG works well, with a probability of error around 4%.
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| 28. |
- Löfhede, Johan, et al.
(författare)
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Classification of burst and suppression in the neonatal electroencephalogram
- 2008
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Ingår i: Journal of Neural Engineering. - : Institute of Physics Publishing Ltd.. - 1741-2560 .- 1741-2552. ; 5:4, s. 402-410
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Tidskriftsartikel (refereegranskat)abstract
- Fisher's linear discriminant (FLD), a feed-forward artificial neural network (ANN) and a support vector machine (SVM) were compared with respect to their ability to distinguish bursts from suppressions in electroencephalograms (EEG) displaying a burst-suppression pattern. Five features extracted from the EEG were used as inputs. The study was based on EEG signals from six full-term infants who had suffered from perinatal asphyxia, and the methods have been trained with reference data classified by an experienced electroencephalographer. The results are summarized as the area under the curve (AUC), derived from receiver operating characteristic (ROC) curves for the three methods. Based on this, the SVM performs slightly better than the others. Testing the three methods with combinations of increasing numbers of the five features shows that the SVM handles the increasing amount of information better than the other methods.
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| 29. |
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| 30. |
- Löfhede, Johan, 1978, et al.
(författare)
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Classifying neonatal EEG
- 2007
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Ingår i: Proceedings of Medicinteknikdagarna 2007. Annual conference of Svensk Förening för Medicinsk Teknik och Fysik. Oct, 2007. Örebro..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In spite of considerable medical progress during the last decades, the perinatal period is still one of the high-risk periods in any individual’s lifetime. In neonatal intensive care of today there is a serious lack of methods that allow continuous monitoring of cerebral function. While we consider it mandatory that good quality hospital care shall include facilities for continuous monitoring of respiratory and cardiac functions in severely ill patients we lack the same possibility when it comes to this most important organ of the body, the brain. The electroencephalogram (EEG) can provide information regarding the state of the brain, but is in its current form not suited for continuous monitoring. Not all neonatal EEG characteristics have been fully investigated or are fully understood, and the people with the necessary competence for interpreting them is not available at neonatal intensive care wards. Our approach is to design a decision support system suitable for continuous monitoring that uses classification algorithms to classify the EEG, for example as normal continuous, normal periodic and pathologic periodic. The EEG is a highly complex signal, and rather than estimating a single parameter, the focus has been on applying classification methods on ensembles of parameters that describe the characteristics of the EEG signal. These parameters have been chosen to enhance different aspects of the EEG signal, and by training classification algorithms with manually segmented data characteristic differences between these complex signals can be found. So far, various classification algorithms have been tested on the task of classifying segments of burst-suppression EEG (pathological periodic) into burst and suppression with rather satisfying results. As a next step we have planned to look into the classification of EEG signals as continuous and periodic, and classification of periodic signals as pathological or normal.
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| 31. |
- Löfhede, Johan, et al.
(författare)
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Comparing a Supervised and an Unsupervised Classification Method for Burst Detection in Neonatal EEG
- 2008
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Ingår i: Proceedings of Engineering in Medicine and Biology Society, EMBS 2008. 30th Annual International Conference of the IEEE, 20-24 August, 2008. - : IEEE. - 1557-170X. - 9781424418145 ; , s. 3836-3839
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Konferensbidrag (refereegranskat)abstract
- Hidden Markov Models (HMM) and Support Vector Machines (SVM) using unsupervised and supervised training, respectively, were compared with respect to their ability to correctly classify burst and suppression in neonatal EEG. Each classifier was fed five feature signals extracted from EEG signals from six full term infants who had suffered from perinatal asphyxia. Visual inspection of the EEG by an experienced electroencephalographer was used as the gold standard when training the SVM, and for evaluating the performance of both methods. The results are presented as receiver operating characteristic (ROC) curves and quantified by the area under the curve (AUC). Our study show that the SVM and the HMM exhibit similar performance, despite their fundamental differences.
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| 32. |
- Löfhede, Johan, 1978, et al.
(författare)
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Comparison of Three Methods for Classifying Burst and Suppression in the EEG of Post Asphyctic Newborns
- 2007
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Ingår i: Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE. - : IEEE. - 1557-170X. - 9781424407880 - 9781424407873 ; , s. 5136-5139
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Konferensbidrag (refereegranskat)abstract
- Fisher's linear discriminant, a feed-forward neural network (NN) and a support vector machine (SVM) are compared with respect to their ability to distinguish bursts from suppression in burst-suppression electroencephalogram (EEG) signals using five features inherent in the EEG as input. The study is based on EEG signals from six full term infants who have suffered from perinatal asphyxia, and the methods have been trained with reference data classified by an experienced electroencephalographer. The results are summarized as area under the curve (AUC) values derived from receiver operating characteristic (ROC) curves for the three methods, and show that the SVM is slightly better than the others, at the cost of a higher computational complexity.
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| 33. |
- Löfhede, Johan, 1978, et al.
(författare)
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Detection of bursts in the EEG of post asphyctic newborns
- 2006
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Ingår i: 2006 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. - 1557-170X. - 9781424400324 ; , s. 2179-2182, s. 5-6
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Konferensbidrag (refereegranskat)abstract
- Eight features inherent in the electroencephalogram (EEG) have been extracted and evaluated with respect to their ability to distinguish bursts from suppression in burst-suppression EEG. The study is based on EEG from six full term infants who had suffered from lack of oxygen during birth. The features were used as input in a neural network, which was trained on reference data segmented by an experienced electroencephalographer. The performance was then evaluated on validation data for each feature separately and in combinations. The results show that there are significant variations in the type of activity found in burst-suppression EEG from different subjects, and that while one or a few features seem to be sufficient for most patients in this group, some cases require specific combinations of features for good detection to be possible.
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| 34. |
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| 35. |
- Mellander, Mats, 1947, et al.
(författare)
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Mineralization defects in deciduous teeth of low birthweight infants.
- 1982
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Ingår i: Acta paediatrica Scandinavica. - 0001-656X. ; 71:5, s. 727-33
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Tidskriftsartikel (refereegranskat)abstract
- A group of 91 children with birthweights below 2000 g and 48 healthy full-term children, reference group, were examined for mineralization disturbances of the enamel of deciduous teeth. Perinatal data were collected retrospectively from obstetric and neonatal records. Within the low birthweight group, children with enamel hypoplasia had on the 5% level a significantly lower intake of breast milk during the first week of life than children without disturbances. The only perinatal complication associated with development of mineralization defects was IRDS. Infants with IRDS, however, had a significantly lower intake of breast milk during the first week of life than low birthweight without IRDS. A low frequency of enamel defects was found in the growth-retarded sub-group of the low birthweight infants. These infants had a significantly higher intake of breast milk during the first week compared to the AGA-group. A seasonal variation was found, with the highest prevalence of mineralization disturbances in infants born during winter months. It is concluded that the occurrence of mineralization defects of the deciduous teeth in LBW infants seems to be dependent upon the amount of breast milk given during the early neonatal period and also possibly in which season of the year they are born.
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| 36. |
- Seoane, Fernando, 1976-, et al.
(författare)
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Brain electrical impedance at various frequencies : the effect of hypoxia
- 2004
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Ingår i: Proceedings of the 26th Annual International Conference of the IEEE EMBS, San Francisco, CA, USA • September 1-5, 2004. - : IEEE Engineering in Medicine and Biology Society. - 0780384393 ; 3, s. 2322-5
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Konferensbidrag (refereegranskat)abstract
- Non-invasive multi-frequency measurements of transcephalic impedance, both reactance and resistance, can efficiently detect cell swelling of brain tissue and can be used for early detection of threatening brain damage. We have performed experiments on piglets to monitor transcephalic impedance during hypoxia. The obtained results have confirmed the hypothesis that changes in the size of cells modify the tissue impedance. During tissue inflammation after induced hypoxia, cerebral tissue exhibits changes in both reactance and resistance. Those changes are remarkably high, up to 71% over the baseline, and easy to measure especially at certain frequencies. A better understanding of the electrical behaviour of cerebral tissue during cell swelling would lead us to develop effective non-invasive clinical tools and methods for early diagnosis of cerebral edema and brain damage prevention.
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| 37. |
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| 38. |
- Seoane Martinez, Fernando, 1976, et al.
(författare)
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Spectroscopy study of the dynamics of the transencephalic electrical impedance in the perinatal brain during hypoxia
- 2005
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Ingår i: Physiological Measurement. - : IOP Publishing. - 0967-3334 .- 1361-6579. ; 26:5, s. 849-863
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Tidskriftsartikel (refereegranskat)abstract
- Hypoxia/ischaemia is the most common cause of brain damage in neonates. Thousands of newborn children suffer from perinatal asphyxia every year. The cells go through a response mechanism during hypoxia/ischaemia, to maintain the cellular viability and, as a response to the hypoxic/ischaemic insult, the composition and the structure of the cellular environment are altered. The alterations in the ionic concentration of the intra- and extracellular and the consequent cytotoxic oedema, cell swelling, modify the electrical properties of the constituted tissue. The changes produced can be easily measured using electrical impedance instrumentation. In this paper, we report the results from an impedance spectroscopy study on the effects of the hypoxia on the perinatal brain. The transencephalic impedance, both resistance and reactance, was measured in newborn piglets using the four-electrode method in the frequency range from 20 kHz to 750 kHz and the experimental results were compared with numerical results from a simulation of a suspension of cells during cell swelling. The experimental results make clear the frequency dependence of the bioelectrical impedance, confirm that the variation of resistance is more sensitive at low than at high frequencies and show that the reactance changes substantially during hypoxia. The resemblance between the experimental and numerical results proves the validity of modelling tissue as a suspension of cells and confirms the importance of the cellular oedema process in the alterations of the electrical properties of biological tissue. The study of the effects of hypoxia/ischaemia in the bioelectrical properties of tissue may lead to the development of useful clinical tools based on the application of bioelectrical impedance technology.
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| 39. |
- Svedin, Pernilla, 1979, et al.
(författare)
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Maturational effects of lipopolysaccharide on white-matter injury in fetal sheep.
- 2005
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Ingår i: Journal of child neurology. - 0883-0738. ; 20:12, s. 960-4
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Tidskriftsartikel (refereegranskat)abstract
- White-matter damage has been associated with the development of cerebral palsy in children born both prematurely and at term, and it has been suggested that intrauterine infection can contribute to the brain injury. However, the relative importance of age on white-matter injury following infectious exposure in utero remains unclear. In this study, fetal sheep were exposed to systemic endotoxemia by administration of Escherichia coli lipopolysaccharide (88.7 +/- 7.7 ng/kg) at 65% or 85% of gestation. These gestational ages approximately correspond to human brain development in preterm and near-term infants respectively. White-matter injury was evaluated 3 days after lipopolysaccharide exposure with regard to microglia activation and loss of neurofilament and myelin basic protein. The expression of oligodendrocytes at different maturational stages was demonstrated in preterm and near-term fetuses with the oligodendroglial markers O4 and 2 ,3 -cyclic nucleotide 3 -phospodiesterase. Forty percent of the fetuses in the preterm group and 22% in the near-term group died within 8 hours of the endotoxin exposure. Three of six preterm and two of seven near-term surviving fetuses demonstrated pathologic changes in the brain with regard to increased microglia activation and loss of neurofilament staining. The number of activated microglia was enhanced in the subcortical white matter in both the preterm lipopolysaccharide-exposed fetuses (lipopolysaccharide: 235 +/- 64 cells/mm2; control: 72 +/- 28 cells/mm2; P = .0374) and the near-term fetuses (lipopolysaccharide: 180 +/- 40 cells/mm2; control 23 +/- 16 cells/mm2; P = .0152). There was a loss of neurofilament staining in both preterm fetuses (lipopolysaccharide: 2.20 +/- 0.77 pixel units; control: 0.20 +/- 0.10 pixel units; P = .0306) and near-term fetuses (lipopolysaccharide: 1.15 +/- 0.48 pixel units; control: 0.06 +/- 0.06 pixel units; P = .0285). O4-positive cells were detected at both gestational ages, whereas 2,3-cyclic nucleotide 3-phospodiesterase-positive cells and myelin basic protein staining were mainly detected in the near-term fetuses. In summary, we found white-matter injury in a proportion of both preterm and near-term fetuses after administration of lipopolysaccharide. These results are in agreement with clinical evidence suggesting that both preterm and term infants are at risk of periventricular leukomalacia in association with intrauterine infection.
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| 40. |
- Sävman, Karin, 1960, et al.
(författare)
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Non-protein-bound iron in brain interstitium of newborn pigs after hypoxia
- 2005
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Ingår i: Dev Neurosci. - : S. Karger AG. - 0378-5866. ; 27:2-4, s. 176-84
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Tidskriftsartikel (refereegranskat)abstract
- Oxidative damage is implied in perinatal hypoxic-ischemic brain injury, most importantly in white matter. Nonprotein-bound iron (NPBI) catalyzes the formation of toxic hydroxyl radicals. We measured the extracellular level of NPBI through microdialysis in the cortex, striatum, and periventricular white matter before, during and after severe hypoxia in newborn pigs. NPBI was analyzed by a new spectrophotometric method in which ferrous iron is chelated by bathophenanthroline. NPBI was present in all brain areas under baseline conditions and increased in white matter from 0.97 (0.69) to 2.75 (1.85) micromol/l (not corrected for recovery rate) during early reoxygenation. NPBI may contribute to oxidative injury after perinatal hypoxic insults.
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| 41. |
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| 42. |
- Thordstein, Magnus, et al.
(författare)
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Effects of inflammation on cerebral electric activity in fetal sheep
- 2008
-
Ingår i: 2nd Congress of the European Academy of Paediatrics, Nice 23-28 okt 2008.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- OBJECTIVE Intrauterine infections can by themselves induce fetal brain damage but also potentiate the effects of other harmful influences such as asphyxia and seizures. Using an EEG technique that permits the recording of extremely low frequencies, often called DC EEG, changes in the level, i.e. DC shifts can be detected. The DC level has been suggested to depend mainly on the potential over the blood brain barrier (BBB), in turn decided primarily by the arterial level of pCO2. Fetuses affected by infection/inflammation that produce detrimental effects on the brain, may have elevated levels of pCO2 and disturbance of the BBB. We aimed at investigating the possibility that the DC EEG could be used to detect the effects of inflammation on the fetal brain. METHODS Fetal sheep were instrumented at 97 days of gestation with catheters, four active EEG electrodes placed on the dura mater as well as extracranial reference and ground electrodes. After three days of recovery, the bacterial endotoxin lipopolysaccharide (LPS) was given to the fetus (200 ng i.v.). RESULTS Exposure to LPS induced a positive DC shift in parallel to the assumed affection of cerebral function and to the pCO2 elevation. This change was not always obvious in standard EEG. CONCLUSIONS These recordings of fetal DC EEG appear to be the first to be done. They indicate that the effects of inflammation on cerebral function can be monitored by DC EEG. Such monitoring might be feasible also during late stages of labour and in neonates.
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| 43. |
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| 44. |
- Thordstein, Magnus, et al.
(författare)
-
Effects of inflammation on cerebral electric activity in fetal sheep
- 2007
-
Ingår i: Sjätte Graz-symposiet om utvecklings-neurologi, Graz 3-5 maj 2007.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- OBJECTIVEIntrauterine infections can by themselves induce fetal brain damage but also potentiate the effects of other harmful influences such as asphyxia and seizures. Using an EEG technique that permits the recording of extremely low frequencies, often called DC EEG, changes in the level, i.e. DC shifts can be detected. The DC level has been suggested to depend mainly on the potential over the blood brain barrier (BBB), in turn decided primarily by the arterial level of pCO2.Fetuses affected by infection/inflammation that produce detrimental effects on the brain, may have elevated levels of pCO2 and disturbance of the BBB. We aimed at investigating the possibility that the DC EEG could be used to detect the effects of inflammation on the fetal brain.METHODSFetal sheep were instrumented at 97 days of gestation with catheters, four active EEG electrodes placed on the dura mater as well as extracranial reference and ground electrodes. After three days of recovery, the bacterial endotoxin lipopolysaccharide (LPS) was given to the fetus (200 ng i.v.).RESULTSExposure to LPS induced a positive DC shift in parallel to the assumed affection of cerebral function and to the pCO2 elevation. This change was not always obvious in standard EEG.CONCLUSIONSThese recordings of fetal DC EEG appear to be the first to be done. They indicate that the effects of inflammation on cerebral function can be monitored by DC EEG. Such monitoring might be feasible also during late stages of labour and in neonates.
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| 45. |
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| 46. |
- Thordstein, Magnus, et al.
(författare)
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Infraslow EEG activity in burst periods from post asphyctic full term neonates
- 2005
-
Ingår i: Clinical Neurophysiology. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 116:7, s. 1501-6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate whether very low EEG frequency activity can be recorded from post asphyctic full term neonates using EEG equipment where the high pass filter level was lowered to 0.05 Hz. METHODS: The time constant of the amplifier hardware was set to 3.2 s in order to enable recordings that equal to a high pass filter cut off at 0.05 Hz. Burst episodes were selected from the EEGs of 5 post asphyctic full term neonates. The episodes were analysed visually using different montages and subjected to power spectrum analysis. Powers in two bands were estimated; 0-1 and 1-4 Hz, designated very low- and low-frequency activity, respectively (VLFA, LFA). RESULTS: In all infants, VLFA coinciding with the burst episodes could be detected. The duration of the VLFA was about the same as that of the burst episode i.e. around 4s. The activity was most prominent over the posterior regions. In this small material, a large amount of VLFA neonatally seemed to possibly be related to a more favourable prognosis. CONCLUSIONS: VLFA can be recorded from post asphyctic full term neonates using EEG equipment with lowered cut off frequency for the high pass filter. SIGNIFICANCE: VLFA normally disregarded due to filtering, is present in the EEG of sick neonates and may carry important clinical information.
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| 47. |
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| 48. |
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| 49. |
- Thordstein, Magnus, et al.
(författare)
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Sex differences in electrocortical activity in human neonates
- 2006
-
Ingår i: Neuroreport. - : Ovid Technologies (Wolters Kluwer Health). - 0959-4965 .- 1473-558X. ; 17:11, s. 1165-8
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral cortical activity in healthy, full-term human neonates (10 boys and 10 girls) was evaluated using spectral estimation of electroencephalogram frequency content with new equipment and analysis technique allowing the assessment of the lowest frequencies (i.e. infraslow waves). The activity was analysed under quiet sleep and active wakefulness taking sex into consideration. During sleep, the mean amount of infraslow activity was 27% larger in boys, whereas during wakefulness the average amount of higher frequencies was 17% larger in girls. Both these differences indicate an earlier maturation of cortical function in girls than in boys.
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| 50. |
- Thordstein, Magnus, et al.
(författare)
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Spectral analysis of burst periods in EEG from healthy and post-asphyctic full-term neonates
- 2004
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Ingår i: Clin Neurophysiol. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 115:11, s. 2461-6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate whether the periodic EEG patterns seen in healthy and sick full term neonates (trace alternant and burst suppression, respectively) have different frequency characteristics. METHODS: Burst episodes were selected from the EEGs of 9 healthy and 9 post-asphyctic full-term neonates and subjected to power spectrum analysis. Powers in two bands were estimated; 0-4 and 4-30 Hz, designated low- and high-frequency activity, respectively (LFA, HFA). The spectral edge frequency (SEF) was also assessed. RESULTS: In bursts, the LFA power was lower in periods of burst suppression as compared to those of trace alternant. The parameter that best discriminated between the groups was the relative amount of low- and high-frequency activity. The SEF parameter had a low sensitivity to the group differences. In healthy neonates, the LFA power was higher over the posterior right as compared to the posterior left region. CONCLUSIONS: Spectral power of low frequencies differs significantly between the burst episodes of healthy and sick neonates. SIGNIFICANCE: These results can be used when monitoring cerebral function in neonates.
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