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Biomedical subjects

K Horn

Publications and source records attributed to K Horn.

At least 19 recordsLinked to original sources
PubMed1992

A comparison of sporozoite and cyst merozoite surface proteins of Sarcocystis.

Surface labeling of Sarcocystis muris and S. suicanis sporozoites with N-hydroxysuccinimide biotin led to the detection of major membrane proteins with relative molecular weights of 29 and 30 kDa, respectively. Immunoblots of Sarcocystis sporozoite proteins probed with sera from infected hosts or with polyclonal monospecific antibodies generated against membrane antigens of cyst merozoites (noncorresponding stages) showed cross-reactivity between the two developmental stages (cyst merozoites and sporozoites) as well as between the species S. muris and S. suicanis. Two-dimensional gel electrophoresis resulted in the identification of isoforms of the sporozoite membrane antigens, with isoelectric points ranging from pH 4.7 to pH 6.4 for S. muris and from pH 4.7 to pH 5.2 for S. suicanis. The molecular masses, the charge heterogeneity, and the immunological reactivity of the surface proteins of Sarcocystis sporozoites were similar to those of cyst merozoites of both species.

Animals↗
PubMed1992

Results of the multicenter evaluation of the CEDIA cortisol assay.

The present paper describes the multicenter evaluation of the CEDIA Cortisol test for total cortisol. The observed linearity of the test was between 1.2 and 50 micrograms/dL cortisol. The limit of detection was calculated as 1.2/dL. Imprecision studies covering the diagnostically relevant range (5-20 micrograms/dL cortisol) yielded coefficients of variation between 1.7-8.9% (within-run) and 2.7-10.5% (between-day). An interlaboratory survey using 41 human samples and three control sera demonstrated that the new CEDIA Cortisol assay has a good interlaboratory transferability. Method comparison studies between the CEDIA Cortisol test and EIA, FIA, FPIA, and various RIAs yielded an acceptable level of agreement and concordant results in most cases. Low cross-reactivity of the antibody used in the new cortisol assay was observed with precursors or metabolites of cortisol. Especially, dexamethasone did not cross-react. However, prednisolone, 6-methylprednisone, and corticosterone showed cross-reactivities. No limitation by endogenous interferences was observed. The CEDIA Cortisol assay permits the precise, fast and sufficiently specific determination of cortisol. Furthermore, it offers the advantages of a non-radioactive assay and can be performed conveniently on Boehringer Mannheim/Hitachi analyzers in combination with routine clinical chemistry.

Humans↗
PubMed1991

Purification of in vitro excysted Sarcocystis sporozoites by passage through a modified DE 52 anion-exchange column.

A method of purifying Sarcocystis sporozoites following in vitro excystation is described. After passage of sporozoites through a modified DE 52 anion-exchange cellulose column, the mean recovery was 88% for S. capracanis, 71% for S. hircicanis, 77% for S. ovicanis and 74% for S. arieticanis. Most of the sporozoites were motile, and the parasite suspension was free of excystation debris.

Animals↗
PubMed1991

Spatial vision of the cat: variation with eccentricity.

We examined the grating acuity and contrast sensitivity of cats whose eye position was monitored with a scleral search-coil technique. During each trial, the cat was required to maintain fixation on a laser spot and respond to the presence or the absence of a grating by pressing a right or left pedal. With this procedure, acuity was measured along the horizontal and vertical meridian over a range of eccentricities in the nasal, temporal, superior, and inferior retina. In addition, contrast sensitivity for stationary and drifting gratings was measured for the temporal retina along the horizontal meridian. Acuity in area centralis reached about 3.5 cycle/deg and declined by 0.5 octaves at 4 deg and by about 1.3 octaves at 16-deg eccentricity in the nasal retina. The acuity was higher in the nasal than temporal retina. At all eccentricities, spatial resolution exceeded the resolution limit derived from Y (alpha)-cell properties. Contrast sensitivity also decreased as the eccentricity increased when the target size was held constant. The slope of sensitivity-eccentricity function was relatively shallow for a low spatial frequency (0.30 cycle/deg) with sensitivity decreasing by a factor of 1.5-2 at 8-deg eccentricity. The slope of the sensitivity falloff for high spatial-frequency gratings (1.2 cycle/deg) was steeper, with a 5-10-fold difference in sensitivity between 0 and 8 deg. By varying the target size, we determined that the summation area in the cat is about a factor of 3 smaller in area centralis than a 16-deg eccentricity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The determination of thyroxine and thyroxine uptake with new homogeneous enzyme immunoassays using Boehringer Mannheim/Hitachi analysis systems.

New homogeneous enzyme immunoassays for the determination of thyroxine and thyroxine uptake have been developed. The CEDIA assays are based on the cloned enzyme donor immunoassay technology, which involves fragments of beta-galactosidase prepared by genetic engineering. The assays have been adapted for Boehringer Mannheim/Hitachi analysers. The CEDIA T4/T Uptake assays were evaluated in eleven clinical chemistry laboratories on various Boehringer Mannheim/Hitachi analysis systems, using a 2-point calibration. The analytical range of the T4 test was 10 to 258 nmol/l thyroxine. The T uptake test had a measuring range between 20-50%. Depending on the concentration of the analyte (samples from hypo-, eu- or hyperthyroid patients), mean coefficients of variation ranged from 1.8 to 4.8% within-run and from 4.1 to 6.5% between-run for the T4 assay. Even better coefficients of variation were obtained for the T uptake assay (1.4 to 2.3% within-run, 2.8 to 3.3% between run). The relative inaccuracy of the CEDIA assays with respect to values assigned by other tests was satisfactory in various control sera. The T4 assay was compared with one radioimmunoassay, one enzyme immunoassay and one fluorescence polarisation immunoassay. Slopes ranging from 0.9 to 1.1 and intercepts ranging from -10 to +10 nmol/l thyroxine were obtained with two exceptions. The results of the T uptake test correlated reasonably with those of other thyroxine-binding methods. No interference was observed with icteric and lipaemic sera. Haemoglobin up to 4 g/l had no significant influence. Results of the CEDIA T Uptake test are mainly used for calculation of the free thyroxine index, in which the thyroxine value is corrected for variations of thyroxine-binding protein concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoanalysis↗
PubMed1991

Environmental medicine.

Four theses appear as the focal point of the paper: 1. Variability and specificity of medical protection of the environment, 2. Interdisciplinary character of the medical environment protection, 3. Medical protection of the environment within the powers of the public health services, 4. Medical protection of the environment as a nationwide issue.

Environmental Exposure↗
PubMed1991

[Carbon disulfide excretion in urine--a biological exposure test for the workplace and environmental concentration ranges].

The biological control procedure for carbon disulphide (CS2), the determination of free and bound CS2 in urine--a procedure already applied to hygienic surveillance--were modified by using gas chromatography and sulphide selective detection (FPD). The results obtained by the changed biological monitoring test in workplace and environmental surveillance are present and discussed. For CS2 concentrations at workplaces in the range of 8-54 mg/m3 a correlation coefficient of r = 0.56 (n = 11, p less than 0.07) was calculated for the mathematical connection of CS2 shift exposure and CS2 content in urine. For environmental exposures in the range of the CS2 immision short term threshold value (MIKK) of 0.03 mg/m3 the procedure may discriminate significantly exposure load from naturally occurring CS2 background.

Adult↗
PubMed1990

[Global 99mTc uptake in the differential diagnosis of a normal thyroid,goiter with euthyroidism and thyroid autonomy in an area of iodine deficiency].

Global TcTU was determined in 568 patients without any specific thyroid drug intake--54 with normal thyroid, 274 with goitre and euthyroidism and 240 with thyroid autonomy. 57 patients with autonomy and overt hyperthyroidism were the only group with TcTU values significantly higher than normals. Common to all groups was a large scatter of the TcTU values. In 332, the effects of individual iodine supply were studied by measuring the iodine concentration in spot urine samples. There was a significant inverse correlation between the TcTU values and the urinary iodine excretion in the groups of normal thyroids and of goitres with euthyroidism. In the group with autonomy an effect of iodine supply could only be seen in cases of greatly increased urinary iodine excretion, resulting in very low TcTU values. Out of 20 patients with autonomy and iodine contamination, only 4 showed overt hyperthyroidism. The large scatter of TcTU values in all groups may be explained by the persistent iodine deficiency as well as by the frequent exposure to unknown amounts of iodine in patients with thyroid disease. Therefore, the spontaneous TcTU alone cannot identify a small group of patients with autonomy and high risk of iodine-induced hyperthyroidism, from a very large group of patients with goitre.

Adult↗
PubMed1990

[Development and application of an environment dosimeter for carbon disulfide].

Construction, function, and quality of parameters of a newly developed passive dosimeter for carbon disulphide are described. CS2 adsorbed on chromosorb 101 is thermically desorbed and then dosed to a gas chromatograph via a gas sampling valve and finally determined by flame photometric detection (FPD). The dosimeter allows 24-hr immission and indoor measurements, respectively, and is also suitable as a personal dosimeter for the environmental concentration range. First practical measurement results are discussed.

Air Pollutants↗
PubMed1990

[Meteorologic effects on dental pain conditions].

Cases of treatment because of acutely occurring states of pain were analysed in a big-city dental outpatients department. The one-year examination covered about 4,000 cases of the total number of 40,000 consultations. As for the diagnoses considered in the examination, it concerned primarily dental caries, acute apical periodontitis and pulpitis. It was to find out if here is a relation between "toothache" and airhygienic influences. This was done with reference to an examination using the same method which was performed as early as in 1982/83. Apparently, there is no immediate correlation.

Air Pollution↗
PubMed1990

[Contamination of public children's playgrounds in Hannover with helminth eggs].

Fifty-two public sand pits on children playgrounds in Hannover were investigated for the presence of parasites. A large proportion (63.5%) of these playgrounds were contaminated with parasite eggs. Eggs from Toxocara spp., Toxascaris leonina and other common helminth parasites were found in 55.8%, 9.6% and 26.1% of these playgrounds, respectively. A total of 208 sand samples were collected, and 30.8% of them contained eggs from Toxocara spp. (24.5%), Toxascaris leonina (2.4%) or other common helminths (9.1%). In 45.1% of the Toxocara positive samples, the eggs were embryonated. Eggs from Toxocara spp. were found in 33.0%, 31.0% or 14.0% of samples from districts with low, medium or high numbers of dogs per hectare, respectively.

Animals↗
PubMed1990

[Quantitative comparison of different methods for the detection of Toxocara canis eggs in sand samples].

Eleven techniques for recovering helminth eggs from sand and soil samples were tested for efficiency and suitability for routine use. The tests were done under standardized conditions on sand samples of 100 g contaminated experimentally with 10, 100 or 1,000 eggs of Toxocara canis. Best results were achieved by a flotation-sedimentation technique (Stoye and Horn, 1986) and by a sieving method (Köhler et al., 1980), showing mean recovery rates of 43.1% and 41.4%, respectively. All other methods tested, mean recovery rates were about 20% or less.

Animals↗
PubMed1990

[Exposure analysis of the effect of air pollution by carbon disulfide].

In the framework of an epidemiological cross sectional study on the medical effects of environmental carbon disulphide loads a specific exposure analysis has been developed concerning this harmful substance. The main point of this analysis is the determination of the individual exposure by personal sampling and biological monitoring, respectively, in addition to emission and in-door measurements. The non-metabolised and acid labile CS2 in urine is determined as the specific biological marker. For characterizing the additional exposure the drinking water, soil, and settlement structure were investigated. Since 1987 this expensive analysis is performed parallel to a specific medical examination programme.

Air Pollutants↗
PubMed1990

[A program of medical examination of the effect of air pollution by carbon disulfide].

For investigating the effect of emissions of the cellulose and rayon silk production on the health state of selected groups of the population as part of an epidemiological cross sectional study on 9-year old school children a medical examination programme with emphasis to the following 5 points--psychological examination, clinical-chemical investigations, lung function analysis, actual state, anamnestic inquiry--has been developed. The programme has been successfully tested in 660 specifically exposed and non-exposed children, respectively. Hitherto performed part evaluations of the mentioned 5 points confirm the correctness of the broadly constructed study.

Air Pollutants↗