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Biomedical subjects

E Schulz

Publications and source records attributed to E Schulz.

At least 163 records · Page 9Linked to original sources
PubMed1984

Contact lens fitting for binocular micromovement recording.

Specially designed hard contact lenses for binocular micromovement recording were tested under static and dynamic conditions. In order to overcome contact lens adherence in fitting 0.2 mm below mean keratometer reading, forces of 70 g were necessary (weight of contact lens 0.058 g). In dynamic testing of induced sinuswave and original micromovement on an experimental globe, pattern identity and synchronism of globe and contact lens are given. Closely spaced saccades were recorded without deformation. Difference in amplitude is due to detector irregularity. Computer calculated time difference in saccadic onset was below 0.003 s. Therefore, requirements are met for micromovement recording in clinical cases and the reliability is outlined.

Contact Lenses↗
PubMed1984

Binocular micromovement recording of human eyes:--methods.

An apparatus is described for binocular recording of micromovements of human eyes, with the contact lens mirror technique used frequently. Horizontal and vertical micromovements of both eyes are recorded simultaneously by means of instruments measuring light-spot positions. Spatial resolution of the measuring instrument is 12 s of arc, while the time resolution is 0.5 ms for this apparatus. The fixation mark (Snellen character) is at a distance of 5 m without any restrictions to the view. The micromovement data are registered by a microcomputer. A second computer enables precise calculation of the results which are given as multicoloured graphs (X/Y-, X/t-graph, velocity/t-graph, frequency analysis, phase correlation of both eyes). In this way the requirements are met for the clinical application of this measuring instrument on patients.

Contact Lenses↗
PubMed1984

Binocular micromovements in normal persons.

Under physiological viewing conditions, binocular micromovements in normal subjects showed multiple saccadic formations which, in their vertical and horizontal components, combined to produce different forms of overshoot which were usually large. On comparing the right and left eyes, micromovements were considerably incongruous, though rough direction identity and absolute synchronism of saccades and drifts were given. Vertical, horizontal and overshoot components of saccades show good correlation in their amplitude/velocity relationship, as seen in voluntary large saccades. Formation, frequency and direction of saccades showed intra-individual similarity rather than dependence on viewing conditions. From our results, we concluded that a central generating process rather than the primary retinal error signals are the source of micromovements during fixation.

Eye Movements↗
PubMed1984

Standardization of a model of E. coli-pyelonephritis in rats.

The validity of preclinical testing of antibiotics in animal experiments is highly dependent on the quality and, especially, the standardizability of the infection model. Some of the factors associated with standardization of the acute phases of infection are demonstrated for experimental pyelonephritis in female albino Wistar rats after transuretheral infection. The renal bacterial count and infection rate are correlated to the volume and bacterial concentration of the instilled E. coli suspension. Strains of albino Wistar rats from different breeding institutions show differing resistance to the infection. E. coli pyelonephritis establishes more easily in female Wistar rats of strain Han: WIST than in strain Bor: WIST. Following dissection of the animals, the infected kidneys can be stored for at least 4 weeks at -30 degrees C or in liquid nitrogen, because the bacterial counts remain constant. However, in frozen renal homogenates the bacterial counts fall rapidly. During the first 4 post-infection days the bacterial content of the kidneys is relatively constant. The period 30-72 h post infection is especially suitable for therapeutic studies.

Animals↗
PubMed1984

Analysis of cephalosporin-induced changes in the volume distribution of Escherichia coli cultures by an electronic counter-channelanalyser.

The demonstration of morphological alterations of the bacterial cell together with bactericidal kinetics are of value for the description of the antibacterial activity of beta-lactam antibiotics. One of the indicators of antibiotic effect on bacterial morphology is the change in bacterial cell volume. This can be demonstrated graphically and numerically by means of electronic cell counting and volume distribution analysis using the Coulter Counter-Channelanalyser system connected to a computer. After registration of the distribution of the relative volume of the Escherichia coli population, the mean cell volume was calculated. The latter parameter increased more than 6 fold with increasing cefotaxim-exposure times. The onset of the delayed (2 h after cefotaxim administration) bacteriolytic effect was reorganized by the appearance of small cell breakdown particles and quantified by counting. In order to demonstrate the therapeutic process graphically the distribution curves were transformed to a common scale. Since a complete storage of the data per sample is performed normally within one minute, the Coulter Counter-Channelanalyser technique can be carried out simultaneously with the bactericidal kinetic experiment. The data demonstrate the speed and intensity of the morphological cell alterations induced by the beta-lactam antibiotic.

Bacteriological Techniques↗
PubMed1984

Different mechanisms of TEM-1 and Oxa-1 mediated resistance to piperacillin in E. coli.

Clinical isolates of Oxa-1 and TEM-1 producing strains of E. coli were studied. Susceptibility to piperacillin was determined by the agar and broth dilution procedure, and beta-lactam hydrolysis rates measured by the iodometric method. The beta-lactamases were identified by isoelectric focusing. Our data on TEM-1 producing strains showed a statistically significant correlation between the MIC, if determined by the agar dilution test, and the specific beta-lactamase activity. The majority of Oxa-1 producing E. coli was resistant to piperacillin although the inactivation rate of piperacillin was usually low. Cell wall permeability of TEM-1 producing strains of E. coli to piperacillin was below the lower limit of detectability, but preincubation of the E. coli strains in piperacillin containing broth led to increased cell wall permeability. Bactericidal kinetics of an Oxa-1 and TEM-1 E. coli were studied. It revealed that regrowth of the Oxa-1 strain in piperacillin containing broth was associated with a 25% decrease of piperacillin concentrations without the formation of degradation products, suggesting binding of piperacillin to bacterial cells. The TEM-1 plasmid bearing strain inactivated piperacillin, and the degradation products (penicilloate) could be detected.

Bacteriolysis↗
PubMed1984

Renal tolerance and pharmacokinetics of vancomycin in rats.

The nephrotoxicity, as measured by urinary cell and enzyme excretion, of vancomycin was studied in rats. The lowest daily iv dose inducing significantly increased cell elimination was 25 mg/kg. Im administration caused less effects probably due to incomplete absorption from the im injection site, since im dosages of 100 mg/kg daily led to lower renal tissue concentrations than the same doses given iv. Nephrotoxicity of vancomycin increased when combined with tobramycin and was reduced when combined with D-glucaro-1.5-lactam, a beta-glucuronidase inhibitor. Vancomycin accumulated in renal tissue during repeated administration.

Animals↗
PubMed1984

[Radioimmunological determination of plasma VIP and serum gastrin concentrations as affected by nutrition].

In 10 volunteers, the plasma VIP and serum gastrin concentrations before and after a test meal were measured at thirty minute intervals over a period of 5 hours. The precision of the VIP radioimmunoassay (double antibody method) is indicated by a coefficient of variation of 6%; its accuracy is reflected by the percentage deviation in the dilution test of between 0.6 and 8.5%. There was no significant difference in VIP concentrations before and after consumption of the test meal (p less than 0.05), WILCOXON test). In contrast, the gastrin concentration had already risen significantly (p less than 0.01) after thirty minutes. It then dropped back to the fasting range over a period of 5 hours. The lack of a rise in VIP after ingestion of the test meal supports the contention that VIP is purely a neurotransmitter. In contrast, the test meal induced a luminal stimulation of G-cells with endocrine secretion.

Adult↗
PubMed1984

[Secretin and cholecystokinin: hormonal action on the concentration of vasoactive intestinal polypeptide and gastrin in human subjects?].

There is little, and partially contradictory information about the mutual hormonal effects of peptides. With the help of volunteers we investigated the influence of a new synthetic secretin (1 CU/kg/h, 0 to 120 min.) alone and in combination with GIH-CCK (1 IU/kg/h, 60 to 120 min.) on the concentration of VIP (n = 13) and gastrin (n = 20). Six of the volunteers were subjected to a randomized cross-over study under NaCl infusion in which both peptides were determined. The VIP concentration was not significantly influenced (31 +/- 3 - 34 +/- 4 - 38 +/- 4.5 pg/ml, p greater than 0.05) by either secretin (0 to 60 min.) or by secretin and CCK (60 to 120 min.). In contrast, secretin induced a significant fall in the gastrin level (30 +/- 2 vs. 24 +/- 2 pg/ml, p less than 0.05). With an additional administration of CCK there was a significant rise in gastrin (75 min.: 46 +/- 3 pg/ml, p less than 0.005) with a decline in peptide levels at the end of the infusion (135 min.: 23 +/- 2 pg/ml, p less than 0.005). The cross reactivity with GIH-CCK and CCK-octapeptide was 2.4 and 3% respectively. The increase in gastrin is not regarded as being due to cross reaction with CCK. This may be due to either contamination of the CCK preparation by other peptides which exert an influence on the gastrin level or the CCK induced release of bile.

Adolescent↗
PubMed1984

The effect of in vivo ozone exposure to Dorset sheep, an animal model with low levels of erythrocyte glucose-6-phosphate dehydrogenase activity.

Female Dorset sheep were exposed in vivo to ambient ozone levels of 0.12 ppm, 0.25 ppm, 0.50 ppm, 0.70 ppm for 2.75 hours and the effects of this exposure upon erythrocytes were studied. Ozone exposure induced biochemical evidence of oxidant stress as indicated by decreases in GSH levels (at 0.5 and 0.7 ppm ozone) and ACHE (at 0.7 ppm), increases in MetHb (from 0.12 ppm upward) and decreases in red blood cell counts (from 0.12 ppm upward). However, only the decrease in GSH levels at the 0.5 ppm ozone exposure was statistically significant (p = 0.05).

Acetylcholinesterase↗
PubMed1984

[Individual variability of lamina V pyramidal neurons in the cingulate area of the rat].

Lamina V-pyramidal neurons of regio precentralis agranularis in Golgi-Kopsch impregnated frontal series of the brains of four adult male rats were analyzed quantitatively in order to estimate the degree of individual variability. As parameters served the dendritic lengths, spine numbers and spine densities along the dendritic orders, within single dendritic fields and within the apical and basal parts of the dendritic tree or of the whole neuron. The significance of individual differences in these parameters between the animals was proven by the tests of Mann and Whitney or of Kruskal and Wallis. The variability turned out to be different in particular subdivisions of the neuron analyzed as well as for the parameter chosen. The basal single dendritic field showed a relative high degree of constancy in its data and the dendritic lengths were statistically more invariable than the spine values. The knowledge about high or less variable parameters in strictly selected neurons is of considerable importance for the planning of experiments followed by quantitative analyses of neurons. The application of the most suitable statistical method is also discussed.

Animals↗
PubMed1984

[Rhythm of diurnal and seasonal urine excretion in calcium oxalate-urinary calculi patients and healthy humans and its effect on the incidence of calculi].

Distinct sinus-like variations in the production of urine - with regard to diurnal as well as seasonal rhythms - result in an increased risk of stone formation in the months of May, June, September and November (concerning seasonal rhythm) and between midnight and 6 a.m. (concerning diurnal rhythm). Other data of importance influencing urinary excretion are sex, age and supply of fluid.

Adolescent↗
PubMed1984

Bilateral deprivation amblyopia.

Two children had toxic bilateral cataracts at the ages of 36 months and 41 months and were deprived of treatment for the next 15 and eight years, respectively. After successful surgery the visual results were about 20/40 in both eyes. This visual recovery suggests that the susceptibility to bilateral stimulus deprivation at this age is slight but not absent, and furthermore that the longtime deprivation beyond the sensitive period does not effect greatly the ultimate outcome of the treatment. Absence of nystagmus supports the opinion that the visual motor system is mature by the age of 3 years.

Adolescent↗
PubMed1984

A cause of right ventricular dysfunction after cardiac operations.

We examined the impact of mediastinal healing on right ventricular performance in three groups of five piglets by performing gated blood pool scans in two planes to determine right ventricular ejection fraction. Animals in Group I then had sternotomy and excision of anterior pericardium. Group II animals had a similar operation plus insertion of a silicone rubber sheet as a pericardial substitute. Group III animals (controls) had no operation. Each group was followed up for 60 days, after which gated blood pool scans were repeated in a manner identical to the initial study. Experimental animals in Groups I and II were then put to death and autopsied. Adhesion formation between the right ventricle and sternum was graded on a 0 to 3 scale. Group I animals showed a significant average decline in right ventricular ejection fraction of 19.2% (p less than 0.02). Group II animals demonstrated an average decrease in ejection fraction, although not significant, of 12.2%. Groups I and II combined showed a significant average loss in ejection fraction of 15.7% (p less than 0.01). Severity of adhesions between the right ventricle and sternum correlated well with loss of right ventricular ejection fraction (p less than 0.01). Group III controls demonstrated no significant change in ejection fraction. Mediastinal healing and fibrous attachment of the right ventricle to the sternum may play a significant role in loss of right ventricular ejection fraction after cardiac operations. Variability in loss of right ventricular ejection fraction is related to intensity of the mediastinal healing process.

Animals↗