Search PubMed⌕ Search

Biomedical subjects

A Karma

Publications and source records attributed to A Karma.

At least 19 recordsLinked to original sources
PubMed2000

Multiscale random-walk algorithm for simulating interfacial pattern formation.

We present a novel computational method to simulate accurately a wide range of interfacial patterns whose growth is limited by a large-scale diffusion field. To illustrate the computational power of this method, we demonstrate that it can be used to simulate three-dimensional dendritic growth in a previously unreachable range of low undercoolings that is of direct experimental relevance.

Algorithms↗
PubMed2000

The expanding clinical spectrum of ocular lyme borreliosis.

OBJECTIVE: To delineate the clinical manifestations of ocular Lyme borreliosis, while concentrating on new symptoms and findings and the phase of appearance of ophthalmologic disorders. DESIGN: Observational case series. PARTICIPANTS: Ten patients with Lyme borreliosis-associated ophthalmologic findings previously reported from the Helsinki University Central Hospital in addition to 10 new cases that have since been diagnosed. INTERVENTION/TESTING: The patients underwent medical and ophthalmologic evaluation. The diagnosis of Lyme borreliosis was based on medical history, clinical ocular and systemic findings, determinations of antibodies to Borrelia burgdorferi by enzyme-linked immunosorbent assay and immunoblot analysis, the detection of DNA of B. burgdorferi by polymerase chain reaction, and exclusion of other infectious and inflammatory causes. MAIN OUTCOME MEASURES: Ocular complaints, presenting ophthalmologic findings, and the stage of Lyme borreliosis were recorded. RESULTS: Four patients presented with a neuro-ophthalmologic disorder, five had external ocular inflammation, 10 patients had uveitis, and one had branch retinal vein occlusion. One patient developed episcleritis and one patient developed abducens palsy within 2 months of the infection incident. In the remaining 14 patients in whom the time of infection was traced, the ocular manifestations appeared in the late stage of Lyme borreliosis. Two patients with a neuro-ophthalmologic disorder and one with external ocular inflammation experienced severe photophobia, whereas the main reported symptom of the patients with uveitis was decreased visual acuity. Four patients with external ocular disease and one with a neuro-ophthalmologic disorder experienced severe periodic ocular or facial pain. Retinal vasculitis developed in seven patients with uveitis. CONCLUSIONS: Lyme borreliosis can cause a variety of ocular manifestations, which develop mainly in the late stage of the disease. Photophobia and severe periodic ocular pain can be characteristic symptoms of Lyme borreliosis. In the differential diagnosis of retinal vasculitis, Lyme borreliosis should be taken into account, especially in endemic areas.

Adult↗
PubMed2000

Search for autoantibodies against the HNK-1 carbohydrate epitope in the human eye in intermediate uveitis.

PURPOSE: Molecules bearing the immunogenic HNK-1 epitope are present in the inner connective tissue layer and epithelia of the ciliary body. We investigated whether autoantibodies to these molecules can be detected in patients with intermediate uveitis, which affects the ciliary body. METHODS: Serum was collected from 9 patients with intermediate uveitis, and from 6 controls with idiopathic iritis and 3 controls with sarcoid uveitis, representing nongranulomatous and granulomatous uveitis, respectively. The sera were used as polyclonal antibodies to immunostain 3 formalin-fixed, paraffin-embedded normal human donor eyes by the avidin-biotinylated peroxidase complex method. RESULTS: No immunostaining in the ciliary body could be detected using the sera from patients with intermediate uveitis or from the controls. Serum within blood vessels was nonspecifically immunolabelled with the secondary anti-human anti-serum. CONCLUSION: No autoantibodies against the HNK-1 epitope or other antigens of the ciliary body could be demonstrated in patients with intermediate uveitis. It is unlikely that such autoantibodies against the HNK-1 epitope have a role in intermediate uveitis.

Adolescent↗
PubMed2000

Three-dimensional dendrite-tip morphology at low undercooling

We investigate the three-dimensional morphology of the dendrite tip using the phase-field method. We find that, for low undercoolings, this morphology is ostensibly independent of anisotropy strength except for a localized shape distortion near the tip that only affects the value of the tip radius rho [which is crudely approximated by rho approximately (1-alpha)rho(Iv) where rho(Iv) is the Ivantsov tip radius of an isothermal paraboloid with the same tip velocity and alpha is the stiffness anisotropy]. The universal tip shape, which excludes this distortion, is well fitted by the form z=-r(2)/2+A(4)r(4) cos 4straight phi where |z| is the distance from the tip and all lengths are scaled by rho(Iv). This fit yields A4 in the range 0.004-0.005 in good quantitative agreement with the existing tip morphology measurements in succinonitrile [LaCombe et al., Phys. Rev. E 52, 2778 (1995)], which are reanalyzed here and found to be consistent with a single cos 4straight phi mode nonaxisymmetric deviation from a paraboloid. Moreover, the fin shape away from the tip is well fitted by the power law z=-a|x|(5/3) with a approximately 0.68. Finally, the characterization of the operating state of the dendrite tip is revisited in the light of these results.

Journal Article↗
PubMed2000

Velocity and shape selection of dendritic crystals in a forced flow

The phase-field method is used to simulate the two-dimensional growth of a dendritic crystal in a forced flow. The selection of the velocity and shape of the dendrite tip is investigated as a function of flow rate, growth direction relative to the flow, as well as anisotropy strength, and the results for the upstream growing tips are compared to existing theoretical predictions.

Journal Article↗
PubMed2000

HLA-B27 typing in the categorisation of uveitis in a HLA-B27 rich population.

AIMS: To determine whether HLA-B27 typing helps the clinician in the diagnostic examination of uveitis in a HLA-B27 rich population and also whether the clinical picture of HLA-B27 positive unilateral acute or recurrent anterior uveitis (AAU) is distinguishable from the idiopathic negative form. METHODS: During a 3 year period 220 consecutive patients with undetermined uveitis at onset were examined in the Helsinki University Eye Clinic. HLA-B27 antigen was tested for 85% of the patients. Other laboratory or x ray examinations were performed on the basis of the anatomical classification of uveitis and the biomicroscopic features characteristic of uveitis associated systemic diseases. RESULTS: HLA-B27 antigen was found significantly more often in patients with anterior (71%) and acute/recurrent unilateral (79%) uveitis than in patients with intermediate, posterior panuveitis (7%), and chronic (7%) or bilateral (12%) forms. Of the 16 cases of HLA-B27 negative unilateral AAU, five showed biomicroscopic features representing uveitis entities. The remaining 11 cases did not differ in any respect from the cases of HLA-B27 positive unilateral AAU. CONCLUSION: HLA-B27 antigen helps the clinician in the diagnostic examination of unilateral AAU. Positive test results serve as a clue to search for spondyloarthropathies, and negative results indicate the need to look for specific uveitis entities and other systemic diseases. The occurrence of HLA-B27 positivity in conjunction with uveitis entities other than unilateral AAU is of the same level or less than in the population of Finland in general.

Acute Disease↗
PubMed1999

The laboratory diagnosis of ocular Lyme borreliosis.

BACKGROUND: A study was carried out to evaluate indirect enzyme-linked immunosorbent assay (ELISA), immunoblot analysis, and polymerase chain reaction (PCR) in the diagnostic work-up of ocular Lyme borreliosis. METHODS: Twenty patients with ocular Lyme borreliosis were examined. IgG and IgM antibodies to Borrelia burgdorferi were measured by ELISA in serum, and in cerebrospinal fluid (CSF) when indicated, and immunoblot analysis of B. burgdorferi IgG antibodies in serum was performed. A nested PCR was used to detect a segment of a gene coding for B. burgdorferi endoflagellin. The samples used in PCR testing were serum and CSF and in isolated cases conjunctiva and vitreous. RESULTS: Seventeen patients had elevated Borrelia antibodies in serum or CSF by ELISA. Seven patients, including two with negative ELISA, had a positive immunoblot. Seven of the 13 patients in whom PCR was examined during clinically active disease had a positive PCR result. Immunoblot analysis gave a negative result from the sera of five PCR-positive patients. CONCLUSIONS: For efficient diagnosis of ocular Lyme borreliosis, immunoblot analysis and PCR should be used in addition to ELISA. A positive PCR seems to be associated with a negative immunoblot.

Adolescent↗
PubMed1997

The etiology of uveitis: the role of infections with special reference to Lyme borreliosis.

PURPOSE: To assess the distribution of different uveitis entities and to evaluate their associations with infections, especially Lyme borreliosis. METHODS: During a one-year period 160 consecutive uveitis patients were evaluated in a university clinic. Selected tests were performed depending on the medical history of the patient and the clinical picture of the ocular inflammation. RESULTS: Uveitis was classified into selected entities for 74.4% of the patients. A direct infection was suggested to be linked with uveitis in 23 patients (14.4%). Lyme borreliosis, toxoplasmosis, and herpetic infections were the most frequently seen, in seven patients (4.3%) each. All patients with Lyme uveitis had manifestations of the posterior segment of the eye, such as vitritis, retinal vasculitis, neuroretinitis, chorioretinitis, or optic neuropathy. CONCLUSION: Infections are an important cause of uveitis in a university clinic. Lyme borreliosis is a newly recognised uveitis entity which should be kept in mind in the differential diagnosis of intermediate or posterior uveitis in areas endemic for Lyme borreliosis.

Adolescent↗
PubMed1996

Long-term follow-up of chronic Lyme neuroretinitis.

PURPOSE: The authors report sequential fluorescein angiographic and color photographic findings of the fundi and response to treatment in a patient with chronic Lyme neuroretinitis. METHODS: A Lyme enzyme-linked immunosorbent assay with purified 41-kd flagellin as antigen was used to detect immunoglobulin G and immunoglobulin M antibodies to Borrelia burgdorferi in serum, cerebrospinal fluid, and vitreous. The changes were documented by fluorescein angiography and color photography tests performed during a 5 1/2 year follow-up. RESULTS: The diagnosis of Lyme neuroretinitis was based on the history of erythema migrans and positive Lyme enzyme-linked immunosorbent assay tests from cerebrospinal fluid and vitreous and by the exclusion of other infectious and systemic diseases and uveitis entities. Fluorescein angiography results disclosed bilateral chronic neuroretinal edema with areas of cystoid, patchy, and diffuse hyperfluorescence peripapillary and in the macular areas. The hyperfluorescent lesions enlarged despite a 9-month period of antibiotic therapy. CONCLUSION: Lyme borreliosis may cause neuroretinitis with unusual angiographic findings. Chronic Lyme neuroretinitis may be unresponsive to antibiotic therapy.

Adult↗
PubMed1996

Ocular manifestations and treatment of Lyme disease.

Ocular manifestations in Lyme disease have been considered rare. In surveys and epidemiologic studies the possibility of ocular Lyme disease has usually not been taken into account. Patients with late ocular. Lyme disease may be seronegative by routine enzyme-linked immunosorbent assays, but immunoblot or detection of Borrelia DNA by polymerase chain reaction may help in diagnosing those cases. An ophthalmologist may suspect the diagnosis of Lyme disease in inflammatory ocular syndromes with unusual biomicroscopic or angiographic findings. Intraocular Lyme disease is usually treated with intravenous ceftriaxone or cefotaxime. Jarisch-Herxheimer reaction may occasionally complicate the antibiotic treatment of ocular manifestations. Overtreatment with ceftriaxone should be avoided because of a possibility of biliary complications.

Eye Diseases↗
PubMed1996

Screening of amblyopic children and long-term follow-up.

A prospective study of amblyopic children was carried out in 1982-1992 in the ophthalmology unit of a community health center, a referral center for 14,000 preschool children. Five hundred and twenty-six children in 1982-1983 were referred to an ophthalmologist because of a suspicion of amblyopia, strabismus or other visual disorders. Amblyopia was diagnosed in 109 children. In 18 children amblyopia was on an organic basis and among them 4 children had X-chromosomal retinoschisis. Risk factors for functional amblyopia were convergent strabismus, spherical equivalent of the refractive error of 3.5 dioptres or more or anisometropia of 1.0 dioptres or more. The children with established functional amblyopia (91 children) were treated with a full-time occlusion, or, at the age of younger than 18 months, with 0.5% atropin, and, at the minimum of 6 years, with pleoptics when indicated. One hundred amblyopic children were followed for a minimum of 4 years, reinstituting the occlusion therapy if visual acuity deteriorated. Seventy-two children with functional amblyopia (79%) were available for a detailed ophthalmological examination 9.7 years, on the average, after the initial examination. Only three of these children (4%) had visual acuity of less than 0.4 at that time. Well-functioning child health centers and school health care, as well as the availability of ophthalmological services, are important for a good final visual result of amblyopic children.

Amblyopia↗