Biomedical subjects
Publications and source records attributed to A Buser.
Cerebral malaria with Plasmodium vivax is uncommon. Normally Plasmodium falciparum is the cause of cerebral malaria. We report about a 18 year old patient from Pakistan with a history of intermittent fever for several months. The patient recovered within a few days; however prognosis can be severe when cerebral malaria is complicating the course of Plasmodium vivax infection.
We studied occurrence, risk factors and outcome of patients with transplant-associated microangiopathy (TAM) after allogeneic stem cell transplantation (HSCT). A total of 221 consecutive patients were transplanted between 1995 and 2002. TAM is defined as evidence of hemolysis and schistocytes in the first 100 days. Outcomes analyzed included TAM and overall survival. Of 221 patients, 68 had TAM. The cumulative incidence was 31 (25-38)% at 100 days. Patients with TAM had higher LDH, higher bilirubin, higher creatinine and more often neurologic symptoms. TAM was not associated with stem cell source, cyclosporine levels and was not more frequent in recent years. In multivariate analysis, risk factors for TAM included donor type, age, gender, ABO-incompatibility and acute graft-versus-host disease (aGvHD). In patients with TAM, 1-year survival was lower than in patients without TAM (27 +/- 18% for TAM with high schistocyte counts; 53 +/- 15% for TAM with low schistocyte counts; vs 78 +/- 7% in patients without TAM; P<0.0001). TAM was independently associated with mortality adjusting for donor type, age and aGvHD occurrence and severity. TAM is frequent after HSCT and is associated with mortality even after adjustment for aGvHD grade. Risk factors of TAM are similar to aGvHD. TAM may represent endothelial damage driven by donor-host interactions.
In hematological neoplasms CD56 (N-CAM) is expressed by T/natural killer (NK) cell lymphoma, by most neoplastic plasma cells in multiple myeloma and also in a subset of acute myelogenous leukemias (AML). In the latter, it is an indicator of poor clinical outcome. Most of the data on CD56 expression in acute leukemia have been obtained by flow cytometric analysis. Up to now, no systematic analysis of the expression pattern of CD56 in formalin fixed paraffin embedded bone marrow biopsies of acute leukemias has been performed. We immunohistochemically studied the expression of CD56 in a series of 141 bone marrow biopsies fixed in Sublimat Mercury II Chloride (SUSA) including 100 cases of AML FAB M0-M7, 11 cases of AML not further specified, 3 cases of biphenotypical leukemia, 20 cases of acute lymphoblastic leukemia (ALL) and 7 cases of reactive bone marrow biopsies. Overall, 14 of 134 (10%) leukemia cases were positive for CD56. Detail analysis revealed positivity in 5/13 cases of AML M5 (38%), 3/9 AML M1 (33%), 1/8 AML M0 (13%), 1/11 AML not specified (9%), 2/31 AML M2 (7%) and 2/26 AML M4 (8%). All cases of ALL and biphenotypic leukemias were CD56 negative. The CD56 expression in AML M5 was statistically significant (p = 0.003). On paraffin embedded bone marrow biopsies CD56 expression occurs in de novo AML with an overall frequency of 13%. It is significantly correlated with AML M5, which is positive in 38% of the cases. Cases of ALL are consistently CD56 negative.
BACKGROUND: This study was carried out to investigate the relationship between the frequency of traffic accidents and impaired vision. MATERIALS AND METHODS: Seven hundred and fifty-four drivers involved in accidents were recruited, in addition to 250 accident-free drivers similar in age and driving experience as an control group. The age distribution of the persons involved in traffic accidents (mean 56.3 years) was similar to that of the control group (mean 57.7 years), the difference was not statistically significant. Both groups underwent a complete ophthalmological examination. RESULTS: All three types of accidents (night-time accidents, violations of right of way, accidents during an overtaking manoeuvre) had a statistically significantly higher incidence of reduced photopic visual acuity, mesopic vision and an increased sensitivity to glare. Some other visual functions were also abnormal, with differences according to the type of accident. In particular, there were noticeable differences between the control group and those who were involved in night-time accidents regarding mesopic vision and sensitivity to glare. Concerning mesopic vision, 15% of the 261 persons involved in night-time accidents did not reach the contrast limit of 1:5; with glare, 20.7% failed. In comparison 4% of the control group reached this critical limit without glare and 7.6% with glare. These differences are highly statistically significant. In contrast to these findings, many of the drivers involved in accidents assessed their own visual capability as "excellent". CONCLUSIONS: The results of this study show that reduced mesopic vision and increased sensitivity to glare are accompanied by an increased risk of night-time accidents (for example, collisions with a non-illuminated obstacle). This emphasizes the importance of regular ophthalmological check-ups including visual functions such as mesopic vision and sensitivity to glare, which currently are not required by the traffic laws in Germany.
Thyroid-associated ophthalmopathy (TAO) is evaluated mainly by orthoptic examination and morphometric parameters such as ultrasound, CT scanning or magnetic resonance imaging. Inflammatory changes of the extraocular muscles lead to an impairment of eye movement. Recent evidence suggests that saccades are altered by changes to the extraocular muscles. Although of potential interest, this phenomenon has so far received little attention. To determine the role of saccades as a potential diagnostic tool for assessing the function of the affected muscles, we have begun to analyze saccadic parameters in patients with TAO. Preliminary results of this study are reported in the present paper. For registration of both horizontal and vertical eye movements, we used the "Ober-2-Apparatus," which uses the infrared technique. Horizontal and vertical saccades with an amplitude of 10 degrees were analyzed in 20 healthy persons and 30 patients suffering from TAO. Patients showed changes in the quality of saccades, such as the appearance of glissades and additional correctional saccades as well as quantitative changes, such as an increase in the maximum speed and latency. Our current data suggest the presence of saccadic alterations in TAO. Our ongoing studies are designed to evaluate whether characteristic changes can be assigned to certain stages of the disease and whether assessment of saccadic changes in a promising tool for early detection and functional follow-up in patients with TAO.
There is currently public discussion as to whether the legal limit of blood alcohol concentration of drivers might be reduced from 0.8% to 0.5%. To acquire information concerning this problem, we measured temporal parameters of saccades and analysed the overall eye-movement behaviour with various blood ethanol concentrations. Eye movements were registered with an IR eye tracker and analysed while the subjects followed a randomly moving stimulus on a CRT screen and during presentation of a realistic traffic scene of 4 min duration on a TV screen. Alcohol has a significant effect on latency, velocity and accuracy of saccades, even at low concentrations between 0.4% and 0.6%. Because of the altered "gaze activity", the inflow of visual information is reduced in a state of inebriation. Our results are a further argument for reducing the legal limit of blood alcohol concentration to 0.5%.
High plus lenses may cause defects in the peripheral visual field. Simple full vision lenses or lenticular lenses without a masked transition zone caused an absolute ring scotoma in the mid-periphery. Patients who were glasses of this type cannot see well enough to drive safely. Although modern edge finishes with masking of the transition zone reduce this problem, visual disturbances in the periphery of the lenses cannot be completely eliminated. A recommendation recently issued by the German Ophthalmological Society concerning maximum lens powers for motorists is aimed at preventing visual field defects of this type.
In daytime traffic the driver experiences a tremendous input of visual information: His problem is to extract the relevant stimuli in order to have an adequate reaction. Traffic at dusk or nighttime, however, is characterized by the fact that even a driver with full visual function approaches his physiological limit. By assessing real traffic situations under various circumstances of weather and illumination (daytime, dusk, nighttime, city traffic, country road) limits of adaptation luminance, object size, object contrast and color are demonstrated. In addition, typical distributions of luminance in the visual field of the driver and the distributions of size and location of relevant objects are quantified. For glare situations typical values of glare angle and corneal illuminance of the glare light and the induced reduction of contrast are determined. Our data demonstrate the type of visual information required by the driver in order to drive safely in road traffic. These data allow conclusions to be made with respect to minimum requirements of visual function for car drivers.
Saccadic eye movements are required for the recognition of peripheral objects in road traffic. Their latencies largely determine reaction time in emergency situations. The aim of this study was to investigate the influence of stimulus and surround parameters on the temporal characteristics of saccadic eye movements under conditions of object size, contrast and luminance corresponding to nighttime traffic. Square stimuli of 1 degree or 5 degrees size were presented under an eccentricity of 5 degrees and 15 degrees. The luminance of the surround was 4 x 10(-4) cd/m2 and 1 cd/m2. More than approx. 2,000 saccades of 7 normal subjects were registered and evaluated with respect to the latency, maximal velocity, and frequency of secondary saccades. At high stimulus contrast, latency approaches a minimum of approx. 200 ms. Latency increases with decreasing contrast up to maximal values of more than 600 ms. Transforming the contrast values into a relative decibel scale shows that this increase in latency occurs at significantly higher relative contrast values under scotopic as compared with photopic conditions. Our results demonstrate that an overall latency of 200-300 ms is not adequate for the assessment of accidents, especially under the stimulus conditions of nighttime traffic.