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Biomedical subjects

L Nyberg

Publications and source records attributed to L Nyberg.

At least 19 recordsLinked to original sources
PubMed2006

A multidisciplinary, multifactorial intervention program reduces postoperative falls and injuries after femoral neck fracture.

INTRODUCTION: This study evaluates whether a postoperative multidisciplinary, intervention program, including systematic assessment and treatment of fall risk factors, active prevention, detection, and treatment of postoperative complications, could reduce inpatient falls and fall-related injuries after a femoral neck fracture. METHODS: A randomized, controlled trial at the orthopedic and geriatric departments at Umeå University Hospital, Sweden, included 199 patients with femoral neck fracture, aged >or=70 years. RESULTS: Twelve patients fell 18 times in the intervention group compared with 26 patients suffering 60 falls in the control group. Only one patient with dementia fell in the intervention group compared with 11 in the control group. The crude postoperative fall incidence rate was 6.29/1,000 days in the intervention group vs 16.28/1,000 days in the control group. The incidence rate ratio was 0.38 [95% confidence interval (CI): 0.20 - 0.76, p=0.006] for the total sample and 0.07 (95% CI: 0.01-0.57, p=0.013) among patients with dementia. There were no new fractures in the intervention group but four in the control group. CONCLUSION: A team applying comprehensive geriatric assessment and rehabilitation, including prevention, detection, and treatment of fall risk factors, can successfully prevent inpatient falls and injuries, even in patients with dementia.

Accidental Falls↗
PubMed2006

Increased risk of dementia following mild head injury for carriers but not for non-carriers of the APOE epsilon4 allele.

BACKGROUND: The epsilon4 allele of apolipoprotein E (APOE) and head injury are risk factors for dementia diseases, and may act synergistically to further increase the risk. The aim of this study was to examine the association between mild head injury, APOE and dementia. METHODS: Data were obtained from the Betula prospective population-based study of aging, memory, and health. The study included 543 participants in the age range 40-85 years, free of dementia at baseline, who were followed up within a 5-year interval. Dementia was classified using DSM-IV criteria. Information on previous head injury was obtained through screening of the participants' answers to health questionnaires at baseline and at follow-up. RESULTS: Subjects with head injury but without APOE epsilon4 had no increased risk of dementia. Subjects with APOE epsilon4 had an increased risk and those with both APOE epsilon4 and head injury had the highest risk of dementia (odds ratio = 5.2). CONCLUSIONS: APOE epsilon4 constitutes a risk factor for dementia, mild injury in isolation does not increase the risk, but head injury in combination with the APOE epsilon4 leads to increased risk of dementia.

Adult↗
PubMed2006

Altered brain white matter integrity in healthy carriers of the APOE epsilon4 allele: a risk for AD?

BACKGROUND: Previous research has shown that polymorphisms of apolipoprotein E (APOE) represent genetic risk factors for dementia and for cognitive impairment in the elderly. The neural mechanisms by which these genetic variations influence behavioral performance or clinical severity are not well understood. METHODS: The authors used diffusion tensor imaging to investigate ultrastructural properties in brain white matter to detect pathologic processes that modify tissue integrity. Sixty participants were included in the study of which 30 were homozygous for the APOE epsilon3 allele, 10 were homozygous for the APOE epsilon4 allele, and 20 had the APOE epsilon34 allele combination. All individuals were non-demented, and the groups were matched on demographic variables and cognitive performance. RESULTS: The results showed a decline in fractional anisotropy, a marker for white matter integrity, in the posterior corpus callosum of epsilon4 carriers compared to non-carriers. Additional sites of altered white matter integrity included the medial temporal lobe. CONCLUSIONS: Although the mechanism underlying vulnerability of white matter tracts in APOE epsilon4 carriers is still unknown, these findings suggest that increased genetic risk for developing Alzheimer disease is associated with changes in microscopic white matter integrity well before the onset of dementia.

Aged↗
PubMed2006

Effect of erythromycin on the absorption of fexofenadine in the jejunum, ileum and colon determined using local intubation in healthy volunteers.

OBJECTIVE: To investigate the in vivo intestinal absorption mechanism(s) and systemic availability of fexofenadine in the jejunum, ileum and colon in humans. METHOD: A single dose of fexofenadine hydrochloride (60 mg as solution) was applied under fasting conditions, either alone or directly after a solution of erythromycin lactobionate (corresponding to a dose of 250 mg erythromycin), to the jejunum, ileum and colon in 6 healthy volunteers (3 male and 3 female) using a regional intubation dosing technology (Bioperm AB, Lund, Sweden). A total of 36 fexofenadine administrations were performed. The administration of fexofenadine to the specified location either alone or in combination with erythromycin was conducted in a randomized manner on 2 consecutive days with a 5-day washout period between doses. RESULTS: The plasma AUC for fexofenadine (mean +/- SEM) was higher (2.7-to 2.3-fold, p < 0.001) after application to the jejunum (1090 +/- 134 h x ng/ml) than to the ileum (404 +/- 102 h x ng/ml) or colon (476 +/- 212 h x ng/ml). No significant differences were found between application to the ileum and colon. The administration of erythromycin affected the absorption rate after jejunal application with a prolonged tmax from a median of 40 min (range 10-90 min) to a median of 3 hours (range 10-180 min) (p = 0.009). A change in tmax was not observed with application to the ileum and colon. The concomitant administration of erythromycin in the jejunum tended to increase the plasma AUC of fexofenadine from 1090 +/- 134 to 1750 +/- 305 h x ng/ml (p = 0.069). CONCLUSIONS: The systemic availability of fexofenadine was significantly higher after jejunal administration in accordance with a low permeability compound. The effects of erythromycin suggest that absorption of fexofenadine involves an uptake transport in addition to passive diffusion in the jejunum and predominantly passive diffusion in the ileum and colon.

Administration, Oral↗
PubMed2004

APOE influences on neuropsychological function after mild head injury: within-person comparisons.

OBJECTIVE: To examine the relationship between neuropsychological outcome following mild head injury (MHI) and APOE genotype. METHODS: Data from a population-based longitudinal study (n = 3,500) were used to identify 34 adults who experienced MHI during the course of the study. Their pre- and postinjury performances on a battery of nine neuropsychological tests were compared within person, and the postinjury performance was compared with that of age- and gender-matched control subjects. RESULTS: The within-person comparisons showed that participants with at least one APOE epsilon4 allele (n = 11) had a significantly decreased postinjury performance on three of the tests, whereas the postinjury performance for APOE epsilon4-negative participants (n = 23) was unchanged. There was no significant difference in postinjury performance between participants with/without the epsilon4 allele, and neither group was impaired relative to controls. CONCLUSIONS: APOE genotype may influence the outcome following an MHI. Pre/postinjury within-person comparisons seem more sensitive than control group comparisons for detecting injury-related effects.

Adult↗
PubMed2004

Cerebral atrophy as predictor of cognitive function in old, community-dwelling individuals.

OBJECTIVES: The impact of cortical and subcortical atrophy on cognitive function was examined in a sample of older community-dwelling men and women. MATERIAL AND METHODS: Magnetic resonance imaging was performed on a sample of 129 individuals [age: 68.4 +/- 3.6 years (mean +/- SD), range 64-74 years, 64 women and 65 men, Mini-Mental State Examination scores above 23] to assess cortical and subcortical atrophy. Participants also performed a number of cognitive tasks, and the measures of atrophy were used to predict performance in these tasks. RESULTS: In men, frontal cortical atrophy predicted worse performance in word fluency and the Stroop test, and occipital cortical atrophy was associated with poor performance in motor speed. In women, poor performance in motor speed was associated with subcortical atrophy at the level of the caudate nucleus. CONCLUSION: Atrophy in certain areas was associated with poor performance in specific cognitive tasks, although the amount of explained variance was rather limited in this quite homogeneous sample.

Aged↗
PubMed2003

Pentosan polysulfate decreases prostate smooth muscle proliferation and extracellular matrix turnover.

Benign prostatic hyperplasia (BPH) involves proliferation of smooth muscle cells and increased deposition of extracellular matrix (ECM). We recently found that pentosan polysulfate (PPS) has marked effects on growth and ECM of smooth muscle cells derived from vascular tissues. We examined smooth muscle cells cultured from human prostates and the effects of PPS on their growth and ECM production. Fragments of surgical prostatectomy specimens were diced, digested with collagenase (0.01%), and placed in culture medium supplemented with 20% fetal bovine serum. Outgrowths of elongated cells were characterized by light microscopic examination and immunohistochemical techniques by the presence of F-actin, alpha-smooth muscle actin, and myosin, which is a characteristic of smooth muscle cells. Two independent isolates were propagated, and growth curves and ECM production were assessed in the presence and absence of PPS (10 or 100 microg/ml). PPS decreased cell number beginning at day 1 and throughout the incubation period, up to 4 days. The amount of the ECM degradative enzymes, metallo-proteinases MMP-9 and MMP-2, was examined by zymography. PPS did not alter the amount of MMP-2 in the supernatants but MMP-9 was increased 234.4 +/- 17.23-fold over control cells. Tissue inhibitor of MMP (TIMPS), examined by reverse zymography, increased 200% over control. The amount of alpha I type (IV) and alpha I type (I) collagen released in the supernatant, measured by ELISA, significantly decreased in PPS-treated cultures. In conclusion, we found that the administration of PPS decreased proliferation as well as ECM production in prostate smooth muscle. Since smooth muscle proliferation and ECM are involved in the pathophysiology of BPH, PPS may have therapeutic potential.

Cell Culture Techniques↗
PubMed2003

Sustained performance and regulation of effort in clinical and non-clinical hyperactive children.

OBJECTIVE: To study sustained performance and its relation to regulation of effort among four different groups of children: two clinical subgroups of children diagnosed with attention-deficit hyperactivity disorder (ADHD)--one with and one without comorbid oppositional defiant disorder (ODD); a control sample of children without a diagnosis of ADHD but with parental reports of hyperactivity; and a normal control sample. METHODS: Sustained performance was studied (n=64) using a choice reaction time task with long interstimulus intervals, and hyperactive behaviour and regulation of effort was rated throughout the task. RESULTS: The clinical sample differed from the normal controls regarding all measures of overall, but not initial, performance. When studying performance over time, the ADHD group was shown to differ from the normal controls with regard to omissions, mean reaction time and regulation of effort. No significant differences were found between the ADHD children with or without comorbid ODD. The non-clinical hyperactive children differed from the normal controls with regard to reaction time, initially and overall, and regulation of effort overall. CONCLUSIONS: Deficits in sustained performance among ADHD children appear to be evident when long interstimulus intervals are used, and these deficits are related to poor regulation of effort. Further, the observed differences between ADHD children and normal controls do not appear to be a result of comorbid conduct problems. The non-clinical hyperactive children were more similar to the control group than to the ADHD group.

Adolescent↗
PubMed2002

Predisposing and precipitating factors for falls among older people in residential care.

Falls and their consequences are serious health problems among older populations. To study predisposing and precipitating factors for falls among older people in residential care we used a cross-sectional study design with a prospective follow up for falls. Fifty-eight women and 25 men, with a mean age of 79.6 y, were included and prospectively followed up regarding falls for a period of 1 y after baseline assessments. All those who fell were assessed regarding factors that might have precipitated the fall. The incidence rate was 2.29 falls/person years. Antidepressants (selective serotonin reuptake inhibitors, SSRIs), impaired vision and being unable to use stairs without assistance were independently associated with being a 'faller'. Twenty-eight (53.8%) of the fallers suffered injuries as a result of their falls, including 21 fractures. Twenty-seven percent of the falls were judged to be precipitated by an acute illness or disease and 8.6% by a side effect of a drug. Acute symptoms of diseases or drug side effects were associated with 58% of the falls which resulted in fractures. We conclude that SSRIs seem to constitute one important factor that predisposes older people to fall, once or repeatedly. Since acute illnesses and drug side-effects were important precipitating factors, falls should be regarded as a possible symptom of disease or a side-effect of a drug until it is proven otherwise.

Accidental Falls↗
PubMed2001

Reactivation of motor brain areas during explicit memory for actions.

Recent functional brain imaging studies have shown that sensory-specific brain regions that are activated during perception/encoding of sensory-specific information are reactivated during memory retrieval of the same information. Here we used PET to examine whether verbal retrieval of action phrases is associated with reactivation of motor brain regions if the actions were overtly or covertly performed during encoding. Compared to a verbal condition, encoding by means of overt as well as covert activity was associated with differential activity in regions in contralateral somatosensory and motor cortex. Several of these regions were reactivated during retrieval. Common to both the overt and covert conditions was reactivation of regions in left ventral motor cortex and left inferior parietal cortex. A direct comparison of the overt and covert activity conditions showed that activation and reactivation of left dorsal parietal cortex and right cerebellum was specific to the overt condition. These results support the reactivation hypothesis by showing that verbal-explicit memory of actions involves areas that are engaged during overt and covert motor activity.

Adult↗
PubMed2001

Controlling mechanisms of aluminium in soil solution--an evaluation of 180 podzolic forest soils.

To monitor the level of soil acidification in the county of Värmland in the middle west of Sweden 180 podzolic forest soils were investigated. Soil solutions from four horizons were obtained by centrifugation and the soil was sampled for a determination of the exchangeable pool by extraction. The concentrations of inorganic Al and its fraction of the total Al in solution were greater in the south of the county (up to 50%). The factors influencing the total Al and free inorganic Al3+ in the soil solutions were evaluated. Saturation indices (SI) for five different mineral phases were calculated but none implied equilibrium conditions. The relationships between pAl3+ and pH (in the pH range 4-6.2) gave slopes of about 1, which indicated that ion exchange/complexation reactions may be important for determining the Al3+ concentration in the B and C horizons. In the E horizon solutions complexation with soluble organic acids seemed to be the major factor which influenced the Al3+ activity. The influence of organic matter on Al solubility was supported by partial least square (PLS) regressions.

Aluminum↗
PubMed2001

Functional neuroimaging of cognition: state-of-the-art.

This paper presents a brief overview of functional neuroimaging studies of cognitive processes. A "publication profile" is identified for PET and fMRI studies of cognitive functions. It is shown that the number of publications has increased exponentially over the last ten years, and that a set of ten journals accounts for the vast majority of publications. It is argued that the field has moved from a state of explorative character to a state of high theoretical sophistication. With special reference to the contributions in this issue of Scandinavian Journal of Psychology, methodological, topical, regional, and clinical implications of cognitive neuroscientific studies are discussed.

Brain↗
PubMed2000

Conjunction analysis of cortical activations common to encoding and retrieval.

The notion of overlap between encoding and retrieval processes is central in cognitive theories of episodic memory, but to date most functional neuroimaging studies have emphasized differences between these processes. In the present study, overlap between encoding and retrieval processes was investigated by analyzing data from a positron emission tomography (PET) study of encoding and retrieval of different kinds of event information. Using a conjunction analysis, we specifically aimed at identifying overlap in activation patterns for encoding and retrieval of three classes of event information: item, temporal, and spatial. It was found that both encoding and retrieval of spatial information activated posterior parietal areas bilaterally. In addition, item encoding and retrieval were associated with increased activity in the right temporal pole, and temporal encoding and retrieval with left inferior frontal and left inferior temporal regions. These findings suggest that when specific episodic information is retrieved from memory, regions involved in encoding of the same information are engaged.

Brain Mapping↗
PubMed2000

Reactivation of encoding-related brain activity during memory retrieval.

Neuronal models predict that retrieval of specific event information reactivates brain regions that were active during encoding of this information. Consistent with this prediction, this positron-emission tomography study showed that remembering that visual words had been paired with sounds at encoding activated some of the auditory brain regions that were engaged during encoding. After word-sound encoding, activation of auditory brain regions was also observed during visual word recognition when there was no demand to retrieve auditory information. Collectively, these observations suggest that information about the auditory components of multisensory event information is stored in auditory responsive cortex and reactivated at retrieval, in keeping with classical ideas about "redintegration, " that is, the power of part of an encoded stimulus complex to evoke the whole experience.

Adult↗
PubMed2000

Activity in motor areas while remembering action events.

Episodic memory for simple commands is better following enacted than verbal encoding. This has been proposed to be due to the possibility to base retrieval on motor information. Here we used PET to test the hypothesis that motor brain areas show increased retrieval-related activity following enacted compared to verbal encoding. Brain activity was also monitored during retrieval after imaginary enactment during encoding. It was found that activity in the right motor cortex was maximal following encoding enactment, intermediate following imaginary encoding enactment, and lowest following verbal encoding. These findings provide support that one basis for the facilitating effect on memory performance of overt, and to a lesser degree covert, encoding enactment is the possibility to base retrieval on motor information.

Adult↗
PubMed2000

Prefrontal cortex and episodic memory retrieval mode.

A multistudy analysis of positron emission tomography data identified three right prefrontal and two left prefrontal cortical sites, as well as a region in the anterior cingulate gyrus, where neuronal activity is correlated with the maintenance of episodic memory retrieval mode (REMO), a basic and necessary condition of remembering past experiences. The right prefrontal sites were near the frontal pole [Brodmann's area (BA) 10], frontal operculum (BA 47/45), and lateral dorsal area (BA 8/9). The two left prefrontal sites were homotopical with the right frontal pole and opercular sites. The same kinds of REMO sites were not observed in any other cerebral region. Many previous functional neuroimaging studies of episodic memory retrieval have reported activations near the frontal REMO sites identified here, although their function has not been clear. Many of these, too, probably have signaled their involvement in REMO. We propose that REMO activations largely if not entirely account for the frontal hemispheric asymmetry of retrieval as described by the original hemispheric encoding retrieval asymmetry model.

Humans↗
PubMed2000

The Mobility Interaction Fall chart.

BACKGROUND AND PURPOSE: The aim of this study was to develop and evaluate a screening tool for the identification of older people living in residential care facilities who are prone to falling. METHOD: Two tests focusing on attentional demands while walking were performed: 'Stops walking when talking' and the 'diffTUG'. Medical assessment, rating for cognition, depression and activities of daily living were also carried out. Falls indoors were followed up prospectively over a period of six months. A flowchart, the Mobility Interaction Fall (MIF) chart, for the identification of older people who are prone to falling was developed. The MIF chart includes an observation of mobility level and 'Stops walking when talking', the diffTUG, a test of vision and a rating of concentration. Study subjects were 78 residents, aged over 65 years, in one residential care facility (22 M; 56 F; median age 82 years, range 66-99 years) in Umeå, Sweden. RESULTS: Thirty-three (42%) subjects suffered at least one fall indoors during the follow-up period. The rate of falls differed significantly between those subjects classified as being at risk of falls and those not so classified (log rank test 39.1; p < 0.001; hazard ratio 12.1; 95% CI 4.6-31.8). The positive predictive value for the classification was 78% (95% CI 67-87%) and the negative predictive value was 88% (95% CI 79-95%). CONCLUSION: The initial findings for the MIF chart indicate a promising way of classifying older people at residential care facilities as being at high or low risk of falling. The classification is quick and easy and requires no expensive equipment.

Accidental Falls↗