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Biomedical subjects

S Samuelsson

Publications and source records attributed to S Samuelsson.

At least 19 recordsLinked to original sources
PubMed2006

Effectiveness of different policies in preventing meningococcal disease clusters following a single case in day-care and pre-school settings in Europe.

National policies for chemoprophylaxis after single cases of meningococcal disease in day-care or nursery settings vary across Europe. We carried out a multi-national retrospective study to compare the effectiveness of different policies. Countries were divided into those recommending chemoprophylaxis only to close contacts (policy A, close) and those recommending chemoprophylaxis for all children in the same nursery (policy B, mass). Country-specific relative risk (RR) of a cluster was defined as the ratio of the number of clusters observed to the number of clusters expected by chance. In total, 37 clusters were identified between 1 January 1993 and 31 December 2002. After adjusting for marked heterogeneity in RR by country, the ratio of RR between countries suggested possible benefit from mass prophylaxis (RR ratio 3.8, 95% CI 0.7-22.0), although the difference was not statistically significant (P=0.22). The costs of this approach and the low risk of clustering need to be taken into account when deciding national policy.

Child↗
PubMed2006

Food does not affect the pharmacokinetics of tesaglitazar, a novel dual peroxisome proliferator-activated receptor alpha/gamma agonist.

Tesaglitazar is a dual peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist in development to treat lipid and glucose abnormalities associated with type 2 diabetes. This study evaluated the effects of food on tesaglitazar pharmacokinetics. In an open, randomized, 2-way crossover study, 20 healthy men received tesaglitazar 1 mg during fasting and after a high-fat, high-calorie breakfast. Blood samples were taken to assess pharmacokinetic variables. Systemic exposure to tesaglitazar was unaffected by food intake. Estimated ratios were 0.99 (90% confidence interval [CI], 0.94-1.04) for fed/fasted area under plasma concentration-time curve and 0.82 (90% CI, 0.78-0.86) for fed/fasted maximum plasma concentration (C(max)). Mean C(max) was approximately 18% lower (0.41 [95% CI, 0.38-0.43] versus 0.50 [95% CI, 0.47-0.53] mumol/L), and median time to C(max) was increased (2.00 vs 0.75 h) in fed versus fasted state. The median difference of t(max) was 1.25 h (P = .0001, signed-rank test). Tesaglitazar was well tolerated. Tesaglitazar pharmacokinetics is unaffected by food intake, allowing once-daily administration of tesaglitazar with or without food in clinical practice.

Adult↗
PubMed2006

Using sentinel surveillance to monitor effectiveness of influenza vaccine is feasible: a pilot study in Denmark.

The influenza vaccine for the season 2003/04 did not contain the circulating A(H3N2)/Fujian virus strain. Vaccine effectiveness (VE) estimates were needed but unavailable. We explored whether or not laboratory based influenza surveillance can be used to estimate VE. We carried out a case-control study nested within Danish sentinel surveillance. A case was defined as a person aged 25 or above with A(H3N2)/Fujian/411/02 influenza. Four controls per case, matched on age groups and time, were selected from clients of sentinel practitioners (SP) who reported cases. SPs collected the following data in structured one-page questionnaires: vaccination status, chronic illness and previous pneumococcal vaccination. We sent postal survey questionnaires to participating SPs to assess acceptability and simplicity of data collection. Twenty four cases were identified. Data from 19 case-control sets were analysed. One control was excluded because information on vaccination status was missing. Two of the 19 cases and 11 of 75 controls had been vaccinated against influenza. The VE adjusted for chronic illness was 33% (95% CI 0%-88%) and 37% (95% CI 0%-89%) when excluding 5 controls with influenza-like illness. Twenty two SPs returned survey questionnaires. Fifteen of 17 SPs reported that it was easy to find controls. SPs collected data through interviews and clinical notes, spending 1 to 5 minutes per case and 5 to 15 minutes for all four controls. Nineteen of 22 SPs considered the amount of time they spent on the study to be acceptable, 17 said that they would like to participate again, and none ruled out further participation. Monitoring VE within sentinel surveillance systems is feasible. The small numbers in our study limit interpretation of VE. Expansion to a European multicountry study could overcome this limitation and provide VE estimates earlier in the season, for different age groups and emerging virus strains, including new and pandemic subtypes.

Adult↗
PubMed2005

Ascertainment of meningococcal disease in Europe.

Meningococcal disease surveillance in most countries is based upon a combination of statutory notification systems and laboratory reporting, both of which are recognised to underestimate the true burden of disease. The incidence of meningococcal disease varies throughout Europe, and although there are many reasons for this, it is important to quantify the degree of under-ascertainment in order to validate international comparisons. Here, we review the literature on the ascertainment of meningococcal disease in Europe and the available methods for estimating the degree of under-reporting. We found that the sensitivity of surveillance varies between countries and over time, with estimates ranging from 40% to 96%. We identified five methods suitable for conducting ascertainment studies, from simple comparative studies to more complicated capture-recapture and regression analyses. Studies of ascertainment may be used to identify weaknesses and biases in surveillance data, and facilitate the improvement of these systems. These findings are relevant to the surveillance of other infectious diseases, particularly those with lower mortality and a lower public profile than meningococcal disease, for which ascertainment may be worse.

Europe↗
PubMed2003

Very-low-birth-weight children at school age: academic achievement, behavior and self-esteem and relation to risk factors.

OBJECTIVE: To investigate school performance, behavior and self-esteem of children with very low birth weight (VLBW). METHODS: All children with birth weight below 1501 g (VLBW) and normal birth weight controls, born in the south-east region of Sweden during a 15-month period in 1987-88, were enrolled in a prospective follow-up study. At the age of 9 years, 81% and 82%, respectively, were re-examined regarding growth, neurofunctional classification, academic achievement tests, need for special education and behavioral problems. At 12 years, 89% and 76%, respectively, were re-examined regarding growth, neurofunctional classification, visual acuity and self-esteem. RESULTS: VLBW children were shorter and lighter, and differed from the controls with regard to neurological functional classification. They produced poorer results in most academic achievement tests. When the comparison was restricted to children with normal intelligence, almost all the differences in other academic achievements disappeared. VLBW children had more reading difficulties but were less often than expected defined as dyslexics compared to control children. We did not find any major disparity in visual acuity and self-esteem between the groups. Low Apgar scores, intracranial hemorrhage and the need for mechanical ventilation neonatally were associated with poorer results in most outcome measures. Neurofunctional assessments in early childhood were associated with most outcome measures. The mother's education was related to delayed reading skills and need for special education. CONCLUSIONS: Although VLBW children performed less well in most academic achievement tests and on some behavioral subscales, those who had a normal intellectual capacity did not differ in any important aspects from the controls.

Achievement↗
PubMed2001

The prevalence of depression in relation to cerebral atrophy and cognitive performance in 70- and 74-year-old women in Gothenburg. The Women's Health Study.

BACKGROUND: Hospital-based studies report that depression in the elderly is associated with brain atrophy. This notion could not be confirmed in a population study on 85-year-olds. We aimed to assess depression in relation to brain atrophy and cognition in 70- and 74-year-old women. METHODS; A representative sample of 70- and 74-year-old women (N = 501) was examined with a psychiatric examination including the Mini-Mental State Examination (MMSE), measuring global cognitive function, and computerized tomography (CT) of the brain (N = 268). Depression was diagnosed according to DSM-III-R. Previous depression was diagnosed by history and by information from previous examinations in this 24-year longitudinal study. RESULTS: The prevalence of depression was 11.6%, including 8.4% with major depression (MDD). Among those who were currently mentally healthy, 43.0% had a history of previous depression. Women with current MDD had lower scores on the MMSE than the mentally healthy women. This association was only found in women with a lower level of education. Current depressives, previous depressives and mentally healthy women without a history of depression did not differ on CT with regard to brain atrophy or white matter lesions. The association between MDD and lower cognitive performance was independent of the association of cognitive performance with structural brain changes on CT. CONCLUSIONS: Brain atrophy on CT is not associated with depression in the general population, despite the fact that individuals with depression have a worse cognitive performance. The finding that cognitive performance was not decreased in individuals with previous depression suggests that cognitive dysfunction is a state phenomenon in depression.

Aged↗
PubMed2000

[School maladjustment common among children with very low birth weight Special attention and support are required during school start].

Children of very low birth weight (VLBW), defined as less than 1500 g, and normal birth weight controls (NBW) were enrolled in a long-term follow-up study. Five of 86 surviving VLBW children had a neurological handicap. Seventy VLBW children and 72 NBW children were re-examined at the age of nine, which entailed a neurological examination, a non-verbal intelligence test and a test for reading ability, mathematical skills and vocabulary. Their behavior was rated regarding hyperactivity, social behavior and fine and motor skills. The two groups differed with regard to the neurological examination and the tests, with poorer results shown for the low birth weight group. The VLBW children were also more hyperactive and scored lower on fine motor skills. Considering only those who scored normally as regards non-verbal intelligence (54% of VLBW children and 88% of controls), practically all differences disappeared.

Attention Deficit Disorder with Hyperactivity↗
PubMed2000

Visual implicit memory deficit and developmental surface dyslexia: a case of early occipital damage.

This study reports the case of EBON, a fifteen-year-old right-handed female Swedish student, who suffered an early medial/dorsal occipital brain lesion and showed a clearly defined pattern of developmental surface dyslexia. EBON and 17 controls were examined with within and cross-modality (visual and auditory) word stem completion tasks together with tasks requiring free-recall and recognition for visually and auditory presented words. Compared to age-matched controls, EBON was found to show a significant deficit of visual priming following visual presentation, and a deficit approaching significance following auditory presentation. Explicit memory and visual and spatial abilities were not significantly different from controls. Therefore, EBON represents the first childhood case establishing the role of occipital regions in visual priming, as well as illustrating a profile of surface reading difficulty as a developmental consequence of this locus of lesion.

Adolescent↗
PubMed2000

Converging evidence for the role of occipital regions in orthographic processing: a case of developmental surface dyslexia.

Recently, there have been several reports focusing on the neural basis for word recognition. Two different views have emerged: one emphasizing the role of the left angular gyrus in recognizing printed words, and the second view suggesting that visual word processing activates the left extrastriate cortex. This paper describes the case of EBON, a 14-year-old girl with an extensive early (most likely congenital) brain lesion in the left occipital lobe. She demonstrates a clear pattern of developmental surface dyslexia in that she is more successful at reading and spelling regular words than irregular words and makes frequent regularization errors. Thus, EBON is the first case reported with the potential to establish converging evidence for the role of extrastriate regions in the left hemisphere in the acquisition of orthographic representations.

Adolescent↗
PubMed2000

Prevention of secondary cases of meningococcal disease in Denmark.

Close contacts of cases of meningococcal disease are at increased risk of disease themselves. We identified household-like contacts of index cases, to investigate whether relevant target groups are informed, receive and follow recommended chemoprophylaxis and vaccination, and to ascertain the time delay for implementation of these measures. A telephone interview of 172 households of index cases and a questionnaire survey among 634 parents of contacts of cases in institutions were carried out. Results were compared with reports from Medical Officers of Health. In 21% of the cases, Medical Officers reported fewer household-like contacts than were identified in this study. Written information was effective. However, 59% of households, and 36% of parents of contacts in institutions felt a lack of information about how the disease is acquired, the risk and signs of illness. For household-like contacts the coverage rate for chemoprophylaxis with an appropriate drug was 90% and for vaccination 59%. No secondary cases occurred among those treated with chemoprophylaxis, but among those not treated, there were two secondary cases. The study design provided a useful audit methodology to evaluate the completeness of implementation and the success of prophylactic measures for meningococcal disease.

Adolescent↗
PubMed2000

Fentanyl and midazolam anaesthesia for coronary bypass surgery: a clinical study of bispectral electroencephalogram analysis, drug concentrations and recall.

Bispectral index (BIS) was assessed as a monitor of depth of anaesthesia during fentanyl and midazolam anaesthesia for coronary bypass surgery. In 10 patients given morphine premedication, anaesthesia was induced with a combination of midazolam and fentanyl and thereafter maintained with a continuous infusion of a mixture of midazolam and fentanyl 5 and 50 micrograms kg-1 h-1, respectively. BIS was recorded continuously but not shown to the attending anaesthetist. Plasma concentrations of midazolam and fentanyl were measured five times during the procedure. An auditory stimulus was given during bypass. All patients were interviewed twice after operation for explicit and implicit recall. No patient had any anaesthetic complications. BIS decreased during anaesthesia, but varied considerably during surgery (range 36-91) with eight patients having values > 60. Midazolam and fentanyl drug concentrations did not correlate with BIS. No patient reported explicit or implicit recall. During clinically adequate anaesthesia with midazolam and fentanyl BIS varies considerably. The most likely reason is that BIS is not an accurate measure of the depth of anaesthesia when using this combination of agents.

Acoustic Stimulation↗
PubMed1999

A speechreading expert: the case of MM.

The present case study of MM, who acquired both sign language and spoken language in her early preschool years-and then reached the normal milestones of development in each language--revealed that her speechreading expertise is associated with cognitive functions such as high working memory capacity and phonological skills. Her cognitive profile is in accord with previous case studies of extremely good speechreading skill. MM's enhanced right prefrontal/frontal cerebral blood flow activation during speechreading seems to be indicative of efficient visual scanning, but it is also possibly due to her strategy for phonological decoding of visual speech.

Adult↗
PubMed1999

Intelligence and dyslexia: implications for diagnosis and intervention.

In this paper we critically examine theoretical issues and practical consequences of including IQ in the definition of dyslexia. According to the discrepancy criterion individuals are classified as dyslexic if their reading skills are below what would be expected from their IQ scores. However, we argue that intelligence is a fuzzy concept and that there is no clear causal relationship between intelligence level and word decoding skills. Also, high and low IQ poor readers show the same reading performance patterns, indicating that both groups might benefit from the same remedial activities. Evidence for the critical role of phonological skills in dyslexia is presented and a more recent definition of dyslexia is discussed in relation to these findings. Finally, two alternative, more outcome-based classifications of poor readers are suggested and some critical consequences for individual interventions are outlined.

Adult↗
PubMed1998

Cognition as a bridge between signal and dialogue: communication in the hearing impaired and deaf.

This paper is an overview of the research we have carried out at Linköping University on cognitive aspects of visual language processing and related communicative forms. In the first section, a cognitive individual difference perspective on speechreading is introduced. In the second, compensatory perceptual mechanisms are discussed on the basis of behavioral and neurophysiological data. The third section addresses further the issue of perceptual versus cognitive compensation, and the fourth and fifth sections apply a set of cognitive tests based on the concept of working memory for poorly specified language input to data on the successes and failures with cochlear implants, tactile aids and hearing aids.

Cognition↗
PubMed1997

Left ventricular function after repeated episodes of ventricular fibrillation and defibrillation assessed by transoesophageal echocardiography.

BACKGROUND: Investigators studying the effects of cardioverter-defibrillators on left ventricular systolic function have given only minor attention to the diastolic effects. OBJECTIVES: The purpose of this study was to investigate the impact of repeated episodes of ventricular fibrillation and defibrillation on systolic function and diastolic filling of the left ventricle during non-thoracotomy implantation of a cardioverter-defibrillator. METHODS: Systolic function and diastolic filling of the left ventricle were assessed peri-operatively on a beat-by-beat basis using a transoesophageal echo-Doppler technique in 12 patients during > or = 4 episodes of ventricular fibrillation and defibrillation. Systolic function was assessed from the fractional area change and diastolic filling from the E/A ratio. Arterial blood pressure and the ECG were recorded continuously. RESULTS: Blood pressure and heart rate did not change significantly throughout the procedure. The systolic function, similarly, was not significantly affected; the only changes were seen in the first two beats after defibrillation when the mean fractional area increased from 0.2 +/- 0.01 to 0.4 +/- 0.02 and 0.3 +/- 0.02, respectively (P < 0.001). Diastolic filling was, however, impaired as reflected by a decrease in the E/A ratio from 2.6 +/- 0.5 before to 1.6 +/- 0.4 (P < 0.01) after repeated threshold tests. CONCLUSIONS: While the combined ischaemic and electrical trauma caused by repeated episodes of ventricular fibrillation and defibrillation during the implantation of a cardioverter-defibrillator did not cause any systolic dysfunction, diastolic filling was significantly impaired.

Adult↗
PubMed1997

Brief episodes of ventricular fibrillation do not influence postischemic cerebral perfusion assessed by positron emission tomography.

OBJECTIVES: To establish the defibrillation threshold in patients receiving an implantable cardioverter defibrillator, at least three episodes of ventricular fibrillation are induced and converted back to regular rhythm, using direct current countershocks. The aim of this study was to examine the influence of repeated short episodes of ventricular fibrillation on global and regional cerebral perfusion. DESIGN: A prospective, descriptive study. SETTING: A positron emission tomography laboratory at a university hospital. PATIENTS: Four patients, admitted for defibrillation threshold tests 2 yrs after the implantation of a cardioverter defibrillator, were included in the study. Global and regional cerebral blood flow was measured by cerebral positron emission tomography, using an 15O-labeled tracer under propofol-induced general anesthesia. Electroencephalograms (EEGs) were concomitantly recorded. INTERVENTIONS: Induction and conversion of ventricular fibrillation. MEASUREMENTS AND MAIN RESULTS: No effect on global cerebral perfusion was observed after induced ventricular fibrillation lasting 21 +/- 3 secs. The average global cerebral perfusion was 23 +/- 1 mL/100 g/min after induction of anesthesia and 31 +/- 8 mL/100 g/min and 24 +/- 2 mL/100 g/min immediately after the termination of the first and second ventricular fibrillation episodes, respectively. Ten minutes after the second and the third threshold tests, global cerebral perfusion was 21 +/- 1 mL/100 g/min and 21 +/- 2 mL/100 g/min, respectively. Regional cerebral perfusion and EEGs were not influenced. CONCLUSION: Short episodes of ventricular fibrillation did not induce any measurable effects on global and regional cerebral perfusion detectable by positron emission tomography 30 secs and 10 mins after restitution of sinus rhythm.

Aged↗