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Ström, Jakob O.
Alternative names
Publications (10 of 33) Show all publications
Ingberg, E., Dock, H., Theodorsson, E., Theodorsson, A. & Ström, J. O. (2018). Effect of laser Doppler flowmetry and occlusion time on outcome variability and mortality in rat middle cerebral artery occlusion: inconclusive results. BMC neuroscience (Online), 19, Article ID 24.
Open this publication in new window or tab >>Effect of laser Doppler flowmetry and occlusion time on outcome variability and mortality in rat middle cerebral artery occlusion: inconclusive results
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2018 (English)In: BMC neuroscience (Online), ISSN 1471-2202, E-ISSN 1471-2202, Vol. 19, article id 24Article in journal (Refereed) Published
Abstract [en]

Background: Stroke is among the leading causes of death and disability. Although intense research efforts have provided promising treatment options in animals, most clinical trials in humans have failed and the therapeutic options are few. Several factors have been suggested to explain this translational difficulty, particularly concerning methodology and study design. Consistent infarcts and low mortality might be desirable in some, but not all, studies. Here, we aimed to investigate whether the use of laser Doppler flowmetry (LDF) and the occlusion time (60 vs. 45 min) affected outcome variability and mortality in a rat stroke model. Eighty ovariectomized female Wistar rats were subjected to ischemic stroke using intraluminal filament middle cerebral artery occlusion with or without LDF and with occlusion times of 45 or 60 min. Outcome was evaluated by triphenyl tetrazolium chloride staining of brain slices to measure infarct size and a modified sticky tape test. Results: Neither LDF nor occlusion times of 45 versus 60 min significantly affected mortality, outcome variability or outcome severity. Conclusions: Due to the unexpectedly high mortality and variability the statistical power was very low and thus the results were inconclusive.

Place, publisher, year, edition, pages
BIOMED CENTRAL LTD, 2018
Keywords
Rats; Middle cerebral artery occlusion; Ischemic stroke; Laser Doppler flowmetry; Mortality; Variability
National Category
Neurology
Identifiers
urn:nbn:se:liu:diva-147934 (URN)10.1186/s12868-018-0425-0 (DOI)000431072000001 ()29673328 (PubMedID)
Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2019-05-01
Appelros, P., Hals Berglund, M. & Ström, J. O. (2017). Long-Term Risk of Stroke after Transient Ischemic Attack. Cerebrovascular Diseases, 43(1-2), 25-30
Open this publication in new window or tab >>Long-Term Risk of Stroke after Transient Ischemic Attack
2017 (English)In: Cerebrovascular Diseases, ISSN 1015-9770, E-ISSN 1421-9786, Vol. 43, no 1-2, p. 25-30Article in journal (Refereed) Published
Abstract [en]

Background: In the absence of active management, the stroke risk after a transient ischemic attack (TIA) may be high. Almost 10 years ago, the results of the EXPRESS and SOS-TIA studies called for a more rapid management of TIA patients. The purpose of this study was to investigate the other stroke risks in the longer term, after the implementation of a more active approach to TIA. We also wanted to assess the predictive value of the ABCD2 score in this context. Methods: Riksstroke is the national stroke registry in Sweden. Data from Riksstrokes TIA module, and the national cause-of-death register, for the years 2011 and 2012 were used in this study. Stroke occurrence was monitored via Riksstroke. Coxs regression was used for risk evaluation. The predictive value of the ABCD2 score was assessed by calculating the area under the receiver operating characteristics curve. Results: A total of 15,068 TIA episodes occurred in 14,102 patients. The follow-up time varied between 0 and 819 days, with an average of 417 days. The mortality for all TIA patients during the follow-up time was 7.1%. Of the unique patients, 545 had one or more strokes (3.9%), corresponding to 34 events per 1,000 person years. Significant risk factors for stroke were: age, previous TIA, atrial fibrillation (AF), oral anticoagulant (OAC) treatment, hypertension treatment, and the ABCD2 items speech impairment, unilateral weakness, and diabetes mellitus. The ABCD2 score correlated with a subsequent stroke, but its predictive value was low. Conclusion: The risk of stroke is low after the acute phase of a TIA, probably lower than in previous studies. This may be due to better secondary prevention in recent years. Several risk factors predict stroke, notably hypertensive treatment, which may be inadequate; and AF, where OACs may be under-used. It is difficult to identify the role of the ABCD2 score in clinical practice. (C) 2016 S. Karger AG, Basel

Place, publisher, year, edition, pages
KARGER, 2017
Keywords
Transient ischemic attack; Stroke risk assessment; Stroke risk factors
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:liu:diva-136076 (URN)10.1159/000451061 (DOI)000394585600005 ()27750222 (PubMedID)
Available from: 2017-03-27 Created: 2017-03-27 Last updated: 2018-05-03
Ruborg, R., Gunnarsson, K. & Ström, J. O. (2017). Predictors of post-stroke body temperature elevation. BMC Neurology, 17, Article ID 218.
Open this publication in new window or tab >>Predictors of post-stroke body temperature elevation
2017 (English)In: BMC Neurology, ISSN 1471-2377, E-ISSN 1471-2377, Vol. 17, article id 218Article in journal (Refereed) Published
Abstract [en]

Background: Growing evidence indicates that elevated body temperature after stroke is associated with unfavorable outcome. The aim of the current study was to investigate which factors predict temperature elevation within 48 h of stroke onset. Specifically, we hypothesized that temperature elevation would be associated with stroke symptom severity and that hemorrhagic stroke would cause a more pronounced temperature increase compared to ischemic stroke. Methods: The medical records of 400 stroke patients were retrospectively reviewed. Multiple linear regression analysis was used to determine which factors were associated with elevated body temperature. Results: Several factors were significantly associated with peak body temperature (the highest recorded body temperature) within 48 h of stroke onset: stroke severity measured by the National Institutes of Health Stroke Scale (NIHSS) (regression coefficient; (RC) 0.022), female gender (RC 0.157), tympanic/non-rectal temperature reading (RC -0.265), swallowing difficulties (RC 0.335), intubation (RC 0.470), antipyretic treatment (RC 0.563), and C-reactive protein amp;gt; 50 or signs of infection at admission (RC 0.298). Contrary to our expectations, patients with intracerebral hemorrhage did not have higher peak body temperatures than patients with ischemic stroke. Conclusions: In conclusion, temperature elevation within the first 48 h of stroke onset is common, can be partially predicted using information at admission and is strongly associated with stroke severity. The strong association with stroke severity may, at least partly, explain the previously described association between post-stroke temperature elevation and unfavorable outcome.

Place, publisher, year, edition, pages
BIOMED CENTRAL LTD, 2017
Keywords
Stroke; Fever; Body temperature; Infection
National Category
Neurology
Identifiers
urn:nbn:se:liu:diva-143990 (URN)10.1186/s12883-017-1002-3 (DOI)000418170700002 ()29237408 (PubMedID)
Note

Funding Agencies|Orebro County Council (Region Orebro lan)

Available from: 2018-01-02 Created: 2018-01-02 Last updated: 2018-05-03
Ivars, K., Nelson Follin, N., Theodorsson, A., Theodorsson, E., Ström, J. & Mörelius, E. (2016). Correction: Development of Salivary Cortisol Circadian Rhythm and Reference Intervals in Full-Term Infants. PLoS ONE, 11(3), Article ID e0151888.
Open this publication in new window or tab >>Correction: Development of Salivary Cortisol Circadian Rhythm and Reference Intervals in Full-Term Infants
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 3, article id e0151888Article in journal, Editorial material (Other academic) Published
Abstract [en]

BACKGROUND:

Cortisol concentrations in plasma display a circadian rhythm in adults and children older than one year. Earlier studies report divergent results regarding when cortisol circadian rhythm is established. The present study aims to investigate at what age infants develop a circadian rhythm, as well as the possible influences of behavioral regularity and daily life trauma on when the rhythm is established. Furthermore, we determine age-related reference intervals for cortisol concentrations in saliva during the first year of life.

METHODS:

130 healthy full-term infants were included in a prospective, longitudinal study with saliva sampling on two consecutive days, in the morning (07:30-09:30), noon (10:00-12:00) and evening (19:30-21:30), each month from birth until the infant was twelve months old. Information about development of behavioral regularity and potential exposure to trauma was obtained from the parents through the Baby Behavior Questionnaire and the Life Incidence of Traumatic Events checklist.

RESULTS:

A significant group-level circadian rhythm of salivary cortisol secretion was established at one month, and remained throughout the first year of life, although there was considerable individual variability. No correlation was found between development of cortisol circadian rhythm and the results from either the Baby Behavior Questionnaire or the Life Incidence of Traumatic Events checklist. The study presents salivary cortisol reference intervals for infants during the first twelve months of life.

CONCLUSIONS:

Cortisol circadian rhythm in infants is already established by one month of age, earlier than previous studies have shown. The current study also provides first year age-related reference intervals for salivary cortisol levels in healthy, full-term infants.

Place, publisher, year, edition, pages
Public Library of Science, 2016
National Category
Pediatrics Psychology (excluding Applied Psychology)
Identifiers
urn:nbn:se:liu:diva-127497 (URN)10.1371/journal.pone.0151888 (DOI)26086734 (PubMedID)
Available from: 2016-04-28 Created: 2016-04-28 Last updated: 2017-11-30Bibliographically approved
Ingberg, E., Theodorsson, E., Theodorsson, A. & Ström, J. (2016). Effects of high and low 17 beta-estradiol doses on focal cerebral ischemia in rats. Scientific Reports, 6(20228)
Open this publication in new window or tab >>Effects of high and low 17 beta-estradiol doses on focal cerebral ischemia in rats
2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 20228Article in journal (Refereed) Published
Abstract [en]

The majority of the numerous animal studies of the effects of estrogens on cerebral ischemia have reported neuroprotective results, but a few have shown increased damage. Differences in hormone administration methods, resulting in highly different 17 beta-estradiol levels, may explain the discrepancies in previously reported effects. The objective of the present study was to test the hypothesis that it is the delivered dose per se, and not the route and method of administration, that determines the effect, and that high doses are damaging while lower doses are protective. One hundred and twenty ovariectomized female Wistar rats (n = 40 per group) were randomized into three groups, subcutaneously administered different doses of 17 beta-estradiol and subjected to transient middle cerebral artery occlusion. The modified sticky tape test was performed after 24 h and the rats were subsequently sacrificed for infarct size measurements. In contrast to our hypothesis, a significant negative correlation between 17 beta-estradiol dose and infarct size was found (p = 0.018). Thus, no support was found for the hypothesis that 17 beta-estradiol can be both neuroprotective and neurotoxic merely depending on dose. In fact, on the contrary, the findings indicate that the higher the dose of 17 beta-estradiol, the smaller the infarct.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2016
National Category
Other Biological Topics
Identifiers
urn:nbn:se:liu:diva-125674 (URN)10.1038/srep20228 (DOI)000369323500001 ()26839007 (PubMedID)
Note

Funding Agencies|County Council of Ostergotland, Sweden

Available from: 2016-03-02 Created: 2016-02-29 Last updated: 2017-05-03
Ingberg, E., Theodorsson, E., Theodorsson, A. & Ström, J. O. (2016). Effects of high and low 17β-estradiol doses on focal cerebral ischemia in rats.
Open this publication in new window or tab >>Effects of high and low 17β-estradiol doses on focal cerebral ischemia in rats
2016 (English)Manuscript (preprint) (Other academic)
Abstract [en]

The majority of the numerous animal studies of the effects of estrogens on cerebral ischemia have reported neuroprotective results, but a few have shown increased damage. Differences in hormone administration methods, resulting in highly different 17β-estradiol levels, may explain the discrepancies in previously reported effects. The objective of the present study was to test the hypothesis that it is the delivered dose per se, and not the route and method of administration, that determines the effect, and that high doses are damaging while lower doses are protective. One hundred and twenty ovariectomized female Wistar rats (n=40 per group) were randomized into three groups, subcutaneously administered different doses of 17β-estradiol and subjected to transient middle cerebral artery occlusion. The modifi ed sticky tape test was performed after 24 h and the rats were subsequently sacrifi ced for infarct size measurements. In contrast to our hypothesis, a signifi cant negative correlation between 17β-estradiol dose and infarct size was found (p=0.018). Thus, no support was found for the hypothesis that 17β-estradiol can be both neuroprotective and neurotoxic merely depending on dose. In fact, on the contrary, the fi ndings indicate that the higher the dose of 17β-estradiol, the smaller the infarct.

National Category
Clinical Medicine Microbiology in the medical area
Identifiers
urn:nbn:se:liu:diva-123890 (URN)
Available from: 2016-01-13 Created: 2016-01-13 Last updated: 2018-01-10Bibliographically approved
Ingberg, E., Dock, H., Theodorsson, E., Theodorsson, A. & Ström, J. O. (2016). Method parameters’ impact on mortality and variability in mouse stroke experiments: a meta-analysis. Scientific Reports, 6
Open this publication in new window or tab >>Method parameters’ impact on mortality and variability in mouse stroke experiments: a meta-analysis
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2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6Article in journal (Refereed) Published
Abstract [en]

Although hundreds of promising substances have been tested in clinical trials, thrombolysis currently remains the only specifi c pharmacological treatment for ischemic stroke. Poor quality, e.g. low statistical power, in the preclinical studies has been suggested to play an important role in these failures. Therefore, it would be attractive to use animal models optimized to minimize unnecessary mortality and outcome variability, or at least to be able to power studies more exactly by predicting variability and mortality given a certain experimental setup. The possible combinations of methodological parameters are innumerous, and an experimental comparison of them all is therefore not feasible. As an alternative approach, we extracted data from 334 experimental mouse stroke articles and, using a hypothesis-driven meta-analysis, investigated the method parameters’ impact on infarct size variability and mortality. The use of Swiss and C57BL6 mice as well as permanent occlusion of the middle cerebral artery rendered the lowest variability of the infarct size while the emboli methods increased variability. The use of Swiss mice increased mortality. Our study offers guidance for researchers striving to optimize mouse stroke models.

Place, publisher, year, edition, pages
Nature Publishing Group, 2016
National Category
Clinical Medicine Microbiology in the medical area
Identifiers
urn:nbn:se:liu:diva-123892 (URN)10.1038/srep21086 (DOI)000370034300001 ()
Note

Funding agencies:  County Council of Ostergotland, Sweden

Vid tiden för disputation förelåg publikationen endast som manuskript

Available from: 2016-01-13 Created: 2016-01-13 Last updated: 2018-01-10Bibliographically approved
Ivars, K., Nelson Follin, N., Theodorsson, A., Theodorsson, E., Ström, J. & Mörelius, E. (2015). Development of Salivary Cortisol Circadian Rhythm and Reference Intervals in Full-Term Infants. PLoS ONE, 10(6), Article ID e0129502.
Open this publication in new window or tab >>Development of Salivary Cortisol Circadian Rhythm and Reference Intervals in Full-Term Infants
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2015 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 6, article id e0129502Article in journal (Refereed) Published
Abstract [en]

Background Cortisol concentrations in plasma display a circadian rhythm in adults and children older than one year. Earlier studies report divergent results regarding when cortisol circadian rhythm is established. The present study aims to investigate at what age infants develop a circadian rhythm, as well as the possible influences of behavioral regularity and daily life trauma on when the rhythm is established. Furthermore, we determine age-related reference intervals for cortisol concentrations in saliva during the first year of life. Methods 130 healthy full-term infants were included in a prospective, longitudinal study with saliva sampling on two consecutive days, in the morning (07:30-09:30), noon (10:00-12:00) and evening (19:30-21:30), each month from birth until the infant was twelve months old. Information about development of behavioral regularity and potential exposure to trauma was obtained from the parents through the Baby Behavior Questionnaire and the Life Incidence of Traumatic Events checklist. Results A significant group-level circadian rhythm of salivary cortisol secretion was established at one month, and remained throughout the first year of life, although there was considerable individual variability. No correlation was found between development of cortisol circadian rhythm and the results from either the Baby Behavior Questionnaire or the Life Incidence of Traumatic Events checklist. The study presents salivary cortisol reference intervals for infants during the first twelve months of life. Conclusions Cortisol circadian rhythm in infants is already established by one month of age, earlier than previous studies have shown. The current study also provides first year age-related reference intervals for salivary cortisol levels in healthy, full-term infants.

Place, publisher, year, edition, pages
Public Library of Science, 2015
National Category
Clinical Medicine Sociology
Identifiers
urn:nbn:se:liu:diva-120229 (URN)10.1371/journal.pone.0129502 (DOI)000356567500051 ()26086734 (PubMedID)
Note

Funding Agencies|County Council of Ostergotland, Sweden; Medical Research Council of Southeast Sweden, FORSS

Available from: 2015-07-21 Created: 2015-07-20 Last updated: 2017-12-04Bibliographically approved
Ingberg, E., Gudjonsdottir, J., Theodorsson, E., Theodorsson, A. & Ström, J. (2015). Elevated body swing test after focal cerebral ischemia in rodents: methodological considerations. BMC neuroscience (Online), 16(50)
Open this publication in new window or tab >>Elevated body swing test after focal cerebral ischemia in rodents: methodological considerations
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2015 (English)In: BMC neuroscience (Online), ISSN 1471-2202, E-ISSN 1471-2202, Vol. 16, no 50Article in journal (Refereed) Published
Abstract [en]

Background: The elevated body swing test (EBST) is a behavioral test used to evaluate experimental stroke in rodents. The basic idea is that when the animal is suspended vertically by the tail, it will swing its head laterally to the left or right depending on lesion side. In a previous study from our lab using the EBST after middle cerebral artery occlusion (MCAo), rats swung contralateral to the infarct day 1 post-MCAo, but ipsilateral day 3 post-MCAo. This shift was unexpected and prompted us to perform the present study. First, the literature was systematically reviewed to elucidate whether a similar shift had been noticed before, and if consensus existed regarding swing direction. Secondly, an experiment was conducted to systematically investigate the suggested behavior. Eighty-three adult male and female Sprague-Dawley rats were subjected to MCAo or sham surgery and the EBST was performed up to 7 days after the lesion. Results: Both experimentally and through systematic literature review, the present study shows that the direction of biased swing activity in the EBST for rodents after cerebral ischemia can differ and even shift over time in some situations. The EBST curve for females was significantly different from that of males after the same occlusion time (p = 0.023). Conclusions: This study highlights the importance of adequate reporting of behavioral tests for lateralization and it is concluded that the EBST cannot be recommended as a test for motor asymmetry after MCAo in rats.

Place, publisher, year, edition, pages
BioMed Central / Springer Verlag (Germany), 2015
Keywords
Brain infarction; Focal cerebral ischemia; Middle cerebral artery occlusion; Elevated body swing test; Rodents; Rats; Lateralization
National Category
Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-120862 (URN)10.1186/s12868-015-0189-8 (DOI)000358984700001 ()26242584 (PubMedID)
Note

Funding Agencies|Region Ostergotland/Linkoping University, Sweden

Available from: 2015-08-28 Created: 2015-08-28 Last updated: 2017-12-04
Ström, J. & Ingberg, E. (2014). Impact of methodology on estrogens’ effects on cerebral ischemia in rats: an updated meta-analysis. BMC neuroscience (Online), 15(22)
Open this publication in new window or tab >>Impact of methodology on estrogens’ effects on cerebral ischemia in rats: an updated meta-analysis
2014 (English)In: BMC neuroscience (Online), ISSN 1471-2202, E-ISSN 1471-2202, Vol. 15, no 22Article in journal (Refereed) Published
Abstract [en]

BACKGROUND:

Although most animal stroke studies have demonstrated potent neuroprotective effects of estrogens, there are a number of articles reporting the opposite. In 2009, we made the case that this dichotomy was related to administered estrogen dose. Several other suggestions for the discordant results have also been propagated, including the age of the experimental animals and the length of hypoestrogenicity prior to estrogen administration. These two suggestions have gained much popularity, probably because of their kinship with the window of opportunity hypothesis, which is commonly used to explain the analogous dichotomy among human studies. We were therefore encouraged to perform an updated meta-analysis, and to improve it by including all relevant variables in a large multiple regression model, where the impact of confounders could be controlled for.

RESULTS:

The multiple regression model revealed an indisputable impact of estrogen administration mode on the effects of estrogens in ischemic stroke. Subcutaneous slow-release pellets differed from the injection and silastic capsule treatments in terms of impact of estrogens on ischemic stroke, showing that the first mentioned were more prone to render estrogens damaging. Neither the use of elderly animals nor the adoption of longer wash-out periods influenced estrogens' effects on experimental ischemic stroke in rats.

CONCLUSIONS:

We conclude that the discordant results regarding estrogens' effects in rat models of ischemic stroke are a consequence of differences in estrogen administration modes. These results are not only of importance for the ongoing debate regarding menopausal hormone therapy, but also have an important bearing on experimental stroke methodology and the apparent translational roadblock for suggested stroke interventions.

Place, publisher, year, edition, pages
BioMed Central, 2014
Keywords
Cerebral ischemia; Estradiol; Estrogens; Meta-analysis; Rats; Stroke
National Category
Basic Medicine
Identifiers
urn:nbn:se:liu:diva-106875 (URN)10.1186/1471-2202-15-22 (DOI)000334885400001 ()24495535 (PubMedID)
Available from: 2014-05-28 Created: 2014-05-23 Last updated: 2018-01-11Bibliographically approved
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