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Biomedical subjects

P Jakobsson

Publications and source records attributed to P Jakobsson.

At least 19 recordsLinked to original sources
PubMed2001

Visual screening of Swedish children: an ophthalmological evaluation.

PURPOSE: This study describes the various ophthalmological conditions detected in the Swedish visual screening program for children. METHODS: The study was longitudinal and retrospective. All children (3126) born in 1982 in three Swedish municipalities have been followed from birth to ten years of age. Visual acuity was examined at the ages of 4, 5.5, 7 and 10 years. Before the age of 4, a gross examination of the eyes was performed. RESULTS: The prevalence of ametropia in the population was 7.7%, the prevalence of strabismus 3.1%, and the prevalence of organic lesions 0.6%. Seven children (0.2%) were visually handicapped (visual acuity </=0.3 in the better eye). Refractive errors and microtropias were mainly detected at the age of 4, when the first visual acuity test was performed, while manifest strabismus was in many cases detected before this age. With this screening and subsequent diagnosis and treatment, the prevalence of deep amblyopia (visual acuity </=0.3) has been reduced from 2% to 0.2%. With treatment, 47% of the amblyopic children achieved a visual acuity better than 0.7. CONCLUSION: Visual screening is effective in detecting visual and ocular disorders. Most conditions are discovered before the age of 6. Compared to an unscreened population, the prevalence of amblyopia is greatly reduced.

Age Distribution↗
PubMed2000

Human glutathione dependent prostaglandin E synthase: gene structure and regulation.

A P1 clone containing the gene for human glutathione dependent PGE synthase (PGES) was isolated and characterized. The gene is divided into three exons, spans 14.8 kb and was localized to chromosome 9q34. 3. In A549 cells, the protein and activity levels of PGES were increased by interleukin-1beta. This increase was prevented by phenobarbital. Reporter constructs containing the 5'-flanking region of exon 1, which exhibited strong promoter activity, responded accordingly, except that interleukin-1beta induced a transient increase followed by a decrease. As cyclooxygenase 2 expression has been reported to respond in a similar fashion, a transcriptional regulatory basis for the observed co-regulation with PGES is implied. The strong down-regulation by phenobarbital raises important issues concerning its mechanisms of action.

Base Sequence↗
PubMed2000

Fourier analysis of steady-state visual evoked potentials in subjects with normal and defective stereo vision.

The purpose of this work was to study the second harmonic in the steady state pattern visual evoked potential (ssVEP) to various stimulus frequencies in subjects with normal and defective binocularity. ssVEPs were elicited by 4 c/deg sinusoidal gratings, with temporal frequencies ranging from 5 to 20 Hz (exp. 1) and 15 to 27.5 Hz (exp. 2). Responses were Fourier analysed and power and phase of the second harmonic to stimulus frequency were measured. For power, binocular enhancement in a bimodal fashion was found both in normals and in subjects with defective binocularity. The power with binocular stimulation was significantly higher in the normal group in the high frequency domain. Latency, estimated from the phase-frequency function, was longer in the group with defective binocularity, but this was statistically significant only for the high frequency domain. The results suggest that a visual system with normal binocular function can follow a stimulus with high temporal frequency more accurately than a system with disturbed binocularity.

Adolescent↗
PubMed1999

Decay of the GRB 990123 optical afterglow: implications for the fireball model

Broad-band (ultraviolet to near-infrared) observations of the intense gamma ray burst GRB 990123 started approximately 8.5 hours after the event and continued until 18 February 1999. When combined with other data, in particular from the Robotic Telescope and Transient Source Experiment (ROTSE) and the Hubble Space Telescope (HST), evidence emerges for a smoothly declining light curve, suggesting some color dependence that could be related to a cooling break passing the ultraviolet-optical band at about 1 day after the high-energy event. The steeper decline rate seen after 1.5 to 2 days may be evidence for a collimated jet pointing toward the observer.

Journal Article↗
PubMed1998

Screening for visual and ocular disorders in children, evaluation of the system in Sweden.

The aim of this study was to evaluate the visual screening system in Sweden. We have made a retrospective investigation of the results of screening for ocular disease and visual impairment of all children born in 1982 in three Swedish communities. The records from screening examinations from 0 to 10 y and from diagnostic follow-up at the departments of ophthalmology that the children were referred to were inspected. The data were used to evaluate the efficiency of the Swedish visual screening system. The study included 3126 children. The attendance rate at the 4-y examination was better than 99%. The sensitivity of the 4- and 5.5-y screening examinations was on the average 92% and the specificity was 97%. The average number of false negative cases at 4 y was 5.6 in 1000 (0.56%). With this screening and subsequent diagnosis and treatment, the prevalence of amblyopia at different levels of visual acuity at the age of 10 y was: 0.06% with visual acuity < or = 0.1, 0.9% with visual acuity < or = 0.5 and 1.7% with visual acuity < or = 0.7. In spite of largely unchanged pressure of amblyogenic factors in the population, the prevalence of deep and moderate amblyopia has been markedly reduced by screening and early treatment.

Amblyopia↗
PubMed1998

Domiciliary liquid oxygen versus concentrator treatment in chronic hypoxaemia: a cost-utility analysis.

Whether long-term oxygen therapy (LTOT) improves quality of life in chronic hypoxaemia has been questioned. LTOT with an oxygen concentrator (C/C) and gas cylinders for ambulation is considered cumbersome compared to mobile liquid oxygen equipment (L). The hypothesis for this study was that LTOT with liquid oxygen treatment (L) improves patients' health-related quality of life, but that it is also more expensive compared to concentrator (C/C) treatment. A prospective, randomized multicentre trial comparing C/C with L for LTOT was conducted during a six-month period. Fifty-one patients (29 on L and 22 on C/C) with chronic hypoxaemia, regularly active outside the home, participated in the study initially. Costs for oxygen were obtained from the pharmacies. Patient diaries and telephone contacts with members of the healthcare sector were used to estimate costs. Health-related quality of life was measured by the Sickness Impact Profile (SIP) and the EuroQol, instruments at the start and after 6 months. The average total cost per patient for group C/C for the six-month period was US$1,310, and for group L it was US$4,950. Health-related quality of life measured by the SIP instrument showed significant differences in favour of group L in the categories/dimensions of physical function, body care, ambulation, social interaction and total SIP score. In conclusion, liquid-oxygen treatment was more expensive compared to concentrator treatment. However, treatment effects showed that liquid oxygen had a better impact on quality of life.

Chronic Disease↗
PubMed1995

A computer and video display based system for training eccentric viewing in macular degeneration with an absolute central scotoma.

A new approach designed to establish the most suitable area for eccentric viewing and to teach and train patients with severe age-related macular degeneration (AMD) to use the eccentric viewing technique is described. Using a computer and video display based system, as well as software written specifically for this purpose, we investigated and trained ten consecutive patients with AMD. The patients were 80.1 + or - 5.6 years old, on average. All of them had an absolute central scotoma. Mean visual acuity was 0.035 + or - 0.016. After 30 min of testing, instruction and reading on the screen, followed by 2.6 + or - 0.69 one-hour training sessions, on average, with the low vision therapist, reading newspaper and book texts with the aid of hyperoculars or aplanatic systems and a very short reading distance, the patients achieved a reading speed of 58.9 + or - 19.7 words/min, significantly (p<0.001) higher than the initial speed when reading on the screen, 11.5 + or - 4.5 words/min.

Aged↗
PubMed1995

Long-term oxygen therapy may improve skeletal muscle metabolism in advanced chronic obstructive pulmonary disease patients with chronic hypoxaemia.

Skeletal muscle metabolite depletion exists in advanced chronic obstructive pulmonary disease (COPD) patients with chronic hypoxaemia. The purpose of this study was to investigate if long-term oxygen therapy (LTOT) can improve skeletal muscle energy metabolism. Eight patients with advanced COPD, four with chronic hypoxaemia, were investigated using muscle biopsy specimens from the quadriceps femoris muscle applying the needle biopsy technique. The investigation was performed twice, before and after approximately 8 months of LTOT in the hypoxaemic patients. Eight healthy controls of similar age were also investigated. In the COPD patients, muscle glycogen, ATP and creatine phosphate (CrP) concentrations, were 42% (P < 0.01), 18% (P < 0.05) and 21% (P = n.s.) lower than in the healthy controls, respectively, while creatine (Cr) and lactate concentrations were 21% and 90% higher, respectively in the COPD patients compared to the healthy control subjects (P < 0.05). After LTOT, the 'energy index' CrP/(CrP + Cr) ratio increased by 0.12 in the LTOT patients but decreased by 0.12 in the control COPD patients (P < 0.05). The results indicate an improvement in skeletal muscle energy metabolism during LTOT in COPD patients with chronic hypoxaemia.

Adenosine Triphosphate↗
PubMed1995

Fat metabolism and its response to infusion of insulin and glucose in patients with advanced chronic obstructive pulmonary disease.

In order to investigate fat metabolism and the regulation of lipolysis and blood fuel metabolites by insulin, nine patients with chronic obstructive pulmonary disease (COPD) with chronic hypoxaemia and seven healthy control subjects of similar age were investigated by determination of the turnover rate of free fatty acids (TOR), using 1-14C-oleic acid as a tracer, and arterial concentrations of FFA, glycerol and 3-hydroxybutyrate. The measurements were performed in the basal state and during insulin and glucose infusion, aiming at euglycaemia at insulin levels of 50 and 100 mU l-1. The subjects' ages were 64 +/- 2.7 and 66 +/- 1.1 (mean +/- SEM) years in the COPD and control groups, respectively. TOR was 0.73 +/- 0.06 and 0.52 +/- 0.02 mmol min-1 (P < 0.05) in the basal state, 0.33 +/- 0.04 and 0.30 +/- 0.02 at an insulin level of 50 mU l-1 and 0.32 +/- 0.08 and 0.24 +/- 0.02 at an insulin level of 100 mU l-1, in the COPD and control groups, respectively. Arterial FFA concentration was 0.98 +/- 0.08 and 0.75 +/- 0.06 mmol l-1 (P < 0.05) in the basal state in the COPD and control groups, respectively. During the clamp, the decrease in FFA mirrored that in TOR. The results show that the state of lipolysis is increased in severe COPD patients with chronic hypoxaemia. Furthermore, the results suggest a reduced effect of insulin in lipolysis.

Aged↗
PubMed1995

Insulin resistance is not exhibited by advanced chronic obstructive pulmonary disease patients.

We have previously reported increased blood glucose concentrations and skeletal muscle glycogen depletion in severe COPD patients with chronic respiratory failure. In order to see if insulin resistance exists in severe COPD, we investigated nine patients with advanced COPD with chronic hypoxaemia and seven healthy control subjects of similar age, using the euglycaemic hyperinsulinaemic glucose clamp technique. We could not demonstrate a subnormal intravenous glucose requirement in response to insulin when maintaining euglycaemia in the COPD patients with chronic hypoxaemia. This indicates that the net metabolism of glucose in COPD patients with chronic hypoxaemia is not resistant to insulin.

Blood Gas Analysis↗
PubMed1995

Screening for ocular dysfunction in children: approaching a common program.

According to the general principles of screening, detection of visual impairment in children is worthwhile, since the condition is a serious health problem, reliable diagnostic tests are available and effective treatment is possible in most instances of ocular and visual dysfunction. However, an evaluation of the screening procedures has not been properly done and the cost-benefit of screening has not been studied. The aim of the present study is to perform a systematic analysis of the screening programs for detection of visual dysfunction. In the screening two parts can be separated, one that concerns the more serious ocular and visual conditions which have to be discovered by general survey methods very early in life, and one that involves detection of less serious conditions, mainly amblyopia, which can be diagnosed by testing for monocular reduction of visual acuity at about 3-4 years of age. The performance characteristics of the screening programs used in Sweden and Canada were evaluated and found to be very favourable. Based on the analysis and the evaluation, recommendations are made on programs for vision screening in children that could be applied more widely. The program could involve all or parts of the following: 1) A careful inspection of the eyes in the neonatal period and preferably also examination of the red reflex with the ophthalmoscope. 2) Children at high risk for ocular and visual disorder, i.e. those born prematurely before 32 weeks of age, or with genetic disease, hearing deficit and/or neurological and mental disorder, should be examined at the proper age by an ophthalmologist. 3) All staff at pediatric departments and child health care centers should be familiar with the visual development of the normal baby and should be alerted to the various symptoms and signs which first warn parents that there may be a visual defect. An inspection of the eyes to detect squint should be part of all pediatric examinations. 4) A screening test of monocular visual acuity in 4 year-old children can be reliably performed by non-ophthalmic personnel after proper training. The screening test should be repeated by school nurses during the first grade of school, and at regular intervals during the school years. 5) The children that screen positively should be seen by ophthalmologists, and in some cases by orthoptists, without undue delay for diagnosis and treatment.

Child↗
PubMed1995

Metabolic enzyme activity in the quadriceps femoris muscle in patients with severe chronic obstructive pulmonary disease.

Eighteen patients with severe COPD and seven healthy control subjects 64.0 +/- 2.2 and 66.8 +/- 1.4 yr of age, respectively (mean +/- SEM), were investigated. Arterial blood gas analysis, dynamic lung volumes, and muscle biopsy specimens from the quadriceps femoris muscle were performed. The muscle biopsies were analyzed for citrate synthase (CS), succinic acid dehydrogenase (SDH), 3-hydroxyacyl-CoA dehydrogenase (HAD), phosphofructokinase (PFK), and lactate dehydrogenase (LDH) activities and related to protein content. The PFK activity was higher in the COPD group than in the control group (+34%, p < 0.05). CS showed a group difference in the opposite direction (-29%, p < 0.05). LDH activity followed PFK and tended to be higher in the patient group (+27%, NS), whereas SDH (-31%, NS) and HAD (-28%, NS) mirrored the CS results. Muscle protein concentration tended to be lower in the COPD group (-14%, NS). There were no significant changes in enzyme activity after 7 mo of long-term oxygen therapy (n = 6). These results indicate adaptation in the form of augmented glycolysis (PFK), and decreased aerobic metabolism (CS) in the quadriceps femoris muscle in patients with advanced COPD.

Citrate (si)-Synthase↗
PubMed1994

Patient positioning for fractionated precision radiation treatment of targets in the head using fiducial markers.

When irradiating targets in the brain, an accurately localised dose is often needed. One crucial moment to achieve this is the positioning of the patient. We have developed a positioning method where the patient is immobilised with a bite block and a head mould, and where the position of the target is determined by X-ray imaging of fiducial markers that are placed in the patient's skull. A method for computing the transformation needed to move the target from the observed to the prescribed position and orientation is described. This method uses the information from two orthogonal X-ray images and takes measurement errors and data from three or more markers into account. Results from using the method clinically in proton beam therapy are given.

Algorithms↗
PubMed1992

The effect of spatial frequency and contrast on the latency in the visual evoked potential.

The latency in the visual evoked potential was measured at spatial frequencies of 2-12 c/deg in 10 subjects. The contrast levels of the sinuosoidal grating patterns were set at 1.5, 1.75, 2.0, 2.25, 2.5, 2.75 and 3.0 log units above each subject's contrast sensitivity threshold. Two factors were shown to influence the latency: suprathreshold contrast and, to a lesser extent, spatial frequency. The visual evoked potential latencies at contrast sensitivity threshold were extrapolated. These threshold latencies showed considerable variation with spatial frequency and between subjects. Therefore, the visual evoked potential latency cannot be considered a useful tool for estimating the contrast sensitivity function.

Adult↗
PubMed1991

The narrow proton beam therapy unit at the the Svedberg Laboratory in Uppsala.

The synchrocyclotron at the The Svedberg Laboratory (TSL) in Uppsala is now reconstructed and can presently operate with fixed frequency and proton energies up to 100 MeV. A first treatment room with a narrow proton beam unit for therapy of eye tumours is now in operation. Therapy of eye melanomas started in April, 1989 and during 1989 and 1990, 19 patients were treated with 72 MeV protons. The narrow beam unit provides a fixed horizontal beam and the patient is treated in a seated position. The present paper describes mainly the technical aspects of the unit which so far has been used only for eye melanomas. In the future, modifications of the unit will allow therapy of intracranial targets when higher proton energies are available. In its final form, the proton therapy facility at TSL will harbour a second treatment unit. Here a rotating gantry for 200 MeV protons will provide a broad beam, which will enable treatment of tumours located anywhere in the body.

Eye Neoplasms↗