Finnbogi Jakobsson - Academia.edu (original) (raw)

Papers by Finnbogi Jakobsson

Journal of Rehabilitation Medicine, May 12, 2020

Isokinetic foot dorsiflexion strength and muscle biopsy data from eight patients with overuse of ... more Isokinetic foot dorsiflexion strength and muscle biopsy data from eight patients with overuse of tibialis anterior muscle (TA) fibres due to weakness after prior polio or L5 root lesion were compared to data from age and sex matched, healthy subjects. Concentric peak torque at an angular velocity of 30 degrees/s was 6-24 Nm in the patients and 15-34 Nm in the controls (p < 0.01). Muscle biopsies from TA showed a significantly higher proportion of type 1 fibres in the patients as compared to the controls (p < 0.005). The type 1 fibres in the patients had a significantly larger cross-sectional area than in the controls (p < 0.005). The type 1 fibre proportion and relative area were inversely correlated to the relative concentric torque produced at 180 degrees/s (p < 0.05) and 240 degrees/s (p < 0.05) compared to that produced at 30 degrees/s in the controls but not in the patients. However, the relative concentric torque produced at 180 degrees/s and 240 degrees/s compared to that produced at 30 degrees/s was not significantly different in the patients and the controls. This indicates that the contractile properties of the overused muscle fibres do not change in parallel with the histochemical fibre type.

Journal of Rehabilitation Medicine

The thigh and lower leg of six patients with prior polio were examined using magnetic resonance i... more The thigh and lower leg of six patients with prior polio were examined using magnetic resonance imaging (MRI), and the strength of their weak foot dorsiflexors was measured isokinetically. Spinecho images of the lower extremities were visually evaluated on a semi-quantitative four-point scale, and T1 and T2 relaxation times of the lower leg anterior compartment were analysed. There were prominent MRI signs of randomly distributed muscle degeneration. The high signal intensity changes in the affected muscles on T1-weighted images and T1 and T2 values indicated replacement of muscle fibres with fat and the accumulation of tissue water, respectively. MRI findings were compared with isokinetic strength in foot dorsiflexor muscles. Foot dorsiflexor peak torque values at 30 deg/s ranged from 6 to 29 Nm. There was no significant correlation between MRI visual scoring, T1 and T2 relaxation times and peak torque values at 30 deg/s. However, the most severe MRI changes with visual scoring and...

ABSTRACT Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn S... more ABSTRACT Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn Skoða/Opna(view/open) A prospective study of acute self poisonings admitted to the Reykjavik City Hospital emergency ward is presented in this paper. The study period was 6 months from December 1983 through May 1984. 145 patients were admitted, 74 females and 71 males. The largest age group was 20-29 years (30%) and 67% of the patients were less than 40 years of age. A drug screening and alchohol assays were performed in 104 cases on admission, and a drug history was obtained in all possible instances. 93 blood samples were positive for drugs and/or alchohol and 24 different drugs were found. Bensodiazepines were by far the most common compounds (52%) and antidepressants came in second (18%). Cannabinoids were found in 3 cases, but they were not routinely looked for. Multiple drugs and a combination of drugs and alchohol were common. A comparison of drug assays and drug history revealed that discrepancies between the purported drug consumption and toxicological results were frequent. A complete agreement was only found in 43% and a partial agreement in 14% of the cases. Most of the poisonings were relatively mild, requiring only short hospitalization. There was one death from hydrochloric acid poisoning. Borgarspítalinn hefur nokkra sérstöðu meðal sjúkrahúsanna í Reykjavik vegna slysadeildarinnar, sem er einasta bráðamóttakan á höfuðborgarsvæðinu. Þangað koma flestir þeir sem þurfa á læknismeðferð eða rannsókn að halda vegna lyfjaeitrana eða gruns um eitranir. Þegar hafa verið gerðar tvær rannsóknir á sjúklingum sem innlagðir voru á lyflækningadeild Borgarspítalans vegna lyfjaeitrana árin 1971-1975 (1) og 1976-1981 (2). Rannsókn sú, sem hér greinir frá, er frábrugðin hinum fyrri að því leyti, að hún er framsýn (prospektiv) og nær til allra sjúklinga, sem komu á slysadeild Borgarspítalans á 6 mánaða tímabili vegna gruns um eitrun. Stuðst var við lyfjamælingar í mun fleiri tilfellum en áður og rannsóknin gefur því miklu nákvæmari mynd af hlutdeild einstakra lyfja og eiturefna en fyrri athuganir, sem styðjast að mestu leyti við lyfjasögu.

The American Journal of Human Genetics, 2002

Stroke is one of the most complex diseases, with several subtypes, as well as secondary risk fact... more Stroke is one of the most complex diseases, with several subtypes, as well as secondary risk factors, such as hypertension, hyperlipidemia, and diabetes, which, in turn, have genetic and environmental risk factors of their own. Here, we report the results of a genomewide search for susceptibility genes for the common forms of stroke. We cross-matched a population-based list of patients with stroke in Iceland with an extensive computerized genealogy database clustering 476 patients with stroke within 179 extended pedigrees. Linkage to 5q12 was detected, and the LOD score at this locus meets the criteria for genomewide significance (multipoint allele-sharing LOD score of 4.40,). A 20-cM region on 5q was physically and genetically mapped to obtain accurate marker 56 P p 3.9 # 10 order and intermarker distances. This locus on 5q12, which we have designated as "STRK1," does not correspond to known susceptibility loci for stroke or for its risk factors and represents the first mapping of a locus for common stroke.

Nature Genetics, 2009

In the version of this article initially published, the SNP rs1049550 listed in the abstract was ... more In the version of this article initially published, the SNP rs1049550 listed in the abstract was indicated incorrectly as a T>C change. It is a C>T change. On the third page of the article, the haplotype containing rs1049550 was incorrectly listed as TATACC. It should be AGCATT. These errors have been corrected in the HTML and PDF versions of the article.

Electroencephalography and Clinical Neurophysiology, 1990

Neuromuscular Disorders, 1994

A~traet-Seven patients with Welander distal myopathy were subjected to magnetic resonance imaging... more A~traet-Seven patients with Welander distal myopathy were subjected to magnetic resonance imaging (MRI) of the lower extremity, and muscle biopsies of the tibialis anterior, soleus and vastus lateralis muscles. MRI revealed abnormalities in both the anterior and posterior compartments of the lower leg in three of the patients, and in only the posterior compartment in the rest of the patients. No MRI abnormalities were found in either the proximal muscles of the leg or in the peroneal or posterior tibial muscle groups. Affected muscles had TI-and T2-values indicating a replacement of muscle fibres with fat tissue. Muscle biopsies showed pathological changes varying from slight to severe in tibialis anterior and soleus muscles in all patients. No muscle fibre abnormalities were seen in the vastus lateralis muscle in any of the patients. In accordance with earlier reports from patients with Welander distal myopathy, there was muscle degeneration of tibialis anterior muscles corresponding to the weakness of dorsal extension of the feet, but also degeneration in the muscles of the posterior compartment. The patients did not, however, show any clinical signs of weakness related to posterior muscle groups. There is no evidence of involvement of proximal muscles of the leg clinically, with MRI or in muscle biopsies.

Muscle & Nerve, 1988

The use of the musculus tibialis anterior during walking and the type and size of its muscle fibe... more The use of the musculus tibialis anterior during walking and the type and size of its muscle fibers were determined in 15 young normal subjects (29 2 4 years) and in 13 old healthy subjects (70 2 3 years). In the average step cycle 16 2 6% of the maximal surface EMG was recorded during the swing phase and 44 ? 15% during 100 rnsec at the heel strike. Single rnotor unit recordings showed that low-threshold units fired at 10-15 Hz during the swing and at 20-25 Hz during the heel strike peak. Usually, highthreshold units did not participate in the ordinary step cycle. A significantly higher mean use was found in the old subjects as compared with the young ones presumably due to lower muscle power in relation to body weight. In the young subjects 76 ? 7% of the muscle fibers were type 1 and 22 ? 7% were type 2A. In the old subjects 84 _i 9% were type 1 and 15 2 8% were type 2A. In the young sub'ects the mean cross-sectional area of type 1 fithe old subjects the corresponding numerals were 4050 ? 890 prn2 and 5700 2 1970 pm2, respectively. The significance of physiological variations in use for muscle fiber type composition and size is discussed. bers was 3950 2 950 Fm a and of type 2 fibers was 8070-+ 1850 pm2. In

Muscle & Nerve, 2012

Introduction: Upper motor neuron lesions after stroke are a major cause of disability. We aimed t... more Introduction: Upper motor neuron lesions after stroke are a major cause of disability. We aimed to determine whether skeletal muscles from these patients display typical molecular signatures of inflammation, growth arrest, and atrophy. Methods: Muscle biopsies were analyzed for morphological, histochemical, ultrastructural, and molecular features indicative of changes in gene expression involved in muscle atrophy. Results: Chronic hemiplegia resulted in $9.5% atrophy, fiber type shifts, and histochemical and ultrastructural signs of impaired remodeling. TNF and TWEAK expressions were unaltered, but MSTN mRNA was lower (À73%, P < 0.05) in paretic tibialis anterior vs. age-matched controls. The expression of autophagy-related genes (BCN-1, LC3, and GABARAPL1) was lower in paretic tibialis anterior (À81%, À48%, and À60%, respectively, P < 0.01) and soleus (À85%, À54%, and À60% respectively, P < 0.01) compared with old controls. Conclusions: Persistent atrophy in chronic spastic hemiplegia may be associated with impaired remodeling partly due to altered autophagy gene expression.

Movement Disorders, 2005

In Iceland, the crude prevalence for all types of primary dystonia was 37.1/10 5 (confidence inte... more In Iceland, the crude prevalence for all types of primary dystonia was 37.1/10 5 (confidence interval, 30.4-44.9). Focal dystonia had the highest prevalence (31.2/10 5), followed by segmental (3.1/10 5), multifocal (2.4/10 5) and generalized dystonia (0.3/10 5). Cervical dystonia was the most common focal dystonia (11.5/10 5), followed by limb dystonia (8.0/10 5), laryngeal dystonia (5.9/10 5), blepharospasm (3.1/10 5), and oromandibular dystonia (2.8/10 5). The male:female ratio for all patients was 1:1.9 (P ϭ 0.0007), and females outnumbered males in all subtypes except oromandibular dystonia. Mean age of onset for all patients was 42.7 years (range, 3-82 years). This prevalence of primary dystonia is higher than in most reported studies, possibly because of more complete ascertainment but the relative frequencies of dystonia subtypes is similar.

Journal of the Neurological Sciences, 1991

Annals of Neurology, 2005

Previous work has suggested that in many neurological diseases genetic variability in the loci pr... more Previous work has suggested that in many neurological diseases genetic variability in the loci predisposing subjects to autosomal dominant disease contributes to the risk of sporadic disease. Here, using a population-based sample of dystonia cases, we show an association with the torsin A haplotype and sporadic idiopathic dystonia.

Acta Neuropathologica, 1990

Muscle biopsies were obtained from the anterior tibial muscle (TA) of 15 healthy, sedentary young... more Muscle biopsies were obtained from the anterior tibial muscle (TA) of 15 healthy, sedentary young (23-37 years) and 13 healthy and physically active elderly (66-77 years) volunteers. The mean frequency of type I fibres was lower in the young subjects compared with the elderly, but the mean type I fibre cross-sectional area was equal in the two groups. The type IIA fibres were, however, smaller in the elderly than in young subjects. Capillary density, capillary per fibre ratio, capillaries in contact with type I fibres (CC) and CC in relation to type I and type II fibre area did not differ in the two groups. The number of capillaries in contact with type IIA fibres was higher in the younger group. Only occasional and minor pathological changes were observed in the young subjects. In the elderly, such changes were much more common, including central nuclei, ring fibres, fibre splitting, scattered highly atrophic fibres, motheaten fibres and vacuoles. Ring fibres were most easily identified with anti-desmin labelling and highly atrophic fibres exhibited a rough network of labelling. Increased content of actin and spectrin was also observed at the periphery of ring fibres. In the elderly group, a qualitative ultrastructural analysis was also obtained and obvious changes included some myofilament loss, collections of lipofuscin which were also observed in satellite cells, proliferation of the SR-T systems and increased wrinkling of nuclear membranes and sarcolemma.

Page 1. 836 LEKNABLADID 1996; 82 Skorpulifur á íslandi Faraldsfrôileg rannsókn Dora Lúôvíksdótti... more Page 1. 836 LEKNABLADID 1996; 82 Skorpulifur á íslandi Faraldsfrôileg rannsókn Dora Lúôvíksdóttir1', Hafsteinn Skúlason11, Finnbogi Jakobsson11, Anna pórisdóttir1', Nick Cariglia2', Bjarki Magnússon3', Bjarni pjóôleifsson4 ...