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Biomedical subjects

U Quast

Publications and source records attributed to U Quast.

At least 145 records · Page 8Linked to original sources
PubMed1979

[Fully automatical control of patient positioning--a new technique leading to exact and safe radiation therapy (author's transl)].

Any motion of the patient causing a displacement of the target volume or an immediate mechanical danger in the course of radiation therapy must be prevented. A new possibility for individual objective monitoring of patient movements, fully automatical, can be presented. Every significant displacement is releasing alarm and is detectable instantaneously. Normal respiratory movements or even the motion of the gantry do not cause a wrong alarm. Important displacements will interrupt the irradiation. Mechanical hazards to the patient thus are almost impossible. First experiences are reported.

Humans↗
PubMed1979

Multidetector endodosimetry probe with silicon-pn-junction-diodes for in-vivo-dosimetry.

In-vivo-dosimetry is necessary to prevent overdosage during radiation treatment techniques of great risk. New special dosemeter probes with up to five Si-pn-junction-diodes in a silicone tube were developed and tested for endodosimetry. They show high efficiency and good linearity of response, without dose-rate dependence. The steep increase of the sensitivity for low energies causes a phantom depth dependence of response. A low temperature dependence but a large anisotropy of response is found for the tested diodes. These multidetector probes proved to be sufficient for direct reading endodosimetric control of dose and dose-distribution during radiotherapy.

Brachytherapy↗
PubMed1979

BCG vaccination of neonates, infants, schoolchildren and adolescents. Part II: Safety of a vaccine with strain 1331 Copenhagen.

The safety of the vaccine could be assessed by three different investigations: a) During the dose finding study (part I) the vaccine showed good safety in all concentrations employed concerning reactions at the site of injection; palpable lymph node enlargement was common. There was one case of suppurative lymphadenitis amond the 262 children who were given the vaccine in the highest concentration (25 X 10(4) VU). b) Subsequent trials in the course of 21 months, when high risk persons could be vaccinated, revealed a rate of this complication in the 1:1,000 range, no case was reported among older persons. c) After the official approval of the vaccine (10 - 30 X 10(4) VU/ml) in the FRG 1 supp. lymphadenitis among 5,000 vaccinated newborns can be calculated.

Adolescent↗
PubMed1979

Mono- and polyneuritis after tetanus vaccination (1970--1977).

Due to the similarity of symptoms, 22 cases of mono- and polyneuritis after tetanus vaccination from our own records covering the years 1970--1977, as well as 6 additional cases taken from existing literature, are being analyzed. As expected, the number of male vaccinees exceede that of female vaccinees, the former being younger than the latter and women generally received less previous tetanus vaccination than men. Three out of four cases occurred during the summer season. The interval between vaccination and the first symptoms was shorter in mononeuritis than in polyneuritis. The prognosis of most cases was benign, irrespective of age, sex and tetanus vaccination history. Cases with delayed recovery only occurred during the summer months. In cases of polyneuritis it seems that the longer the interval between vaccination and the first symptoms, the slower the recovery. It has to be emphasized that the discussed cases of neuritis have to be viewed as extremely rare complications due to tetanus vaccine.

Adult↗
PubMed1979

Vaccine induced mumps-like diseases.

Sixteen cases of parotitis and 2 cases of diabetes mellitus after mumps vaccination have been reported since the introduction of the live attenuated mumps vaccine in the F. R. Germany in the fall of 1976. Due to the post-vaccination incubation of 7 to 10 days, support is given to the assumption that these cases are vaccine induced and not coincidental wild virus infections. The diabetes mellitus cases, however, are too few to be included in this rational.

Diabetes Mellitus↗
PubMed1979

Adverse reactions after pertussis vaccination.

During 1970 to 1977 adverse reactions after pertussis vaccination were reported for 149 persons, 56% male and 44% female. Their symptoms permitted to divide the vaccinees into 2 groups, the first with more severe (S) and the second with other symptoms (O). No differences were observed in age and sex among the two groups. The interval between vaccination and appearance of first symptoms was longer for the O than for the S group. While less than one quarter of the reactions in the O group occurred after primovaccination, more than half of the S side effects were seen after the first vaccination. Further analysis of the S group revealed that all but two of their symptoms (fever and encephalopatht) corresponded to the hypoglycaemic syndrome. The consequences hereof are discussed with regard to prevention and therapy.

Child↗
PubMed1978

Ligand-induced conformation changes in Torpedo californica membrane-bound acetylcholine receptor.

A time-dependent increase in ligand affinity has been studied in cholinergic ligand binding to Torpedocalifornica acetylcholine receptor by inhibition of the kinetics of of [125I]-alpha-bungarotoxin-receptor complex formation. The conversion of the acetylcholine receptor from low to high affinity form was induced by both agonists and antagonists of acetylcholine and was reversible upon removal of the ligand. The slow ligand induced affinity change in vitro resembled electrophysiological desensitization observed at the neuromuscular junction and described by a two-state model (Katz, B., & Thesleff, S. (1957) J. Physiol. 138, 63). A quantitative treatment of the rate and equilibrium constants determined for binding of the agonist carbamoylcholine to membrane bound acetylcholine receptor indicated that the two-state model is not compatible with the in vitro results.

Acetylcholine↗
PubMed1978

Kinetics of the interaction of alpha-chymotrypsin with trypsin kallikrein inhibitor (Kunitz) in which the reactive-site peptide bond Lys-15--Ala-16 is split.

Modified trypsin kallikrein inhibitor (I*), with the reactive-site peptide bond Lys-15--Ala-16 split, reacts with alpha-chymotrypsin (E) via an intermediate X to the stable tetrahedral complex C:E + I in equilibrium X leads to C. Formation X constitutes a fast pre-equilibrium (equilibrium constant Kx = 7 X 10(-5) M, association rate constant kx = 4 X 10(3)M-1s-1) to the slow reaction X leads to C (rate constant kc = 2 X 10(-3) s-1), all values at pH 7.5. No intermediate X is observed when alpha-chymotrypsin reacts with I*-OMe in which the carboxyl group of Lys-15 is esterified by methanol. This observation as well as the different pH dependence of the overall association rate constants in the case of I* and I*-OMe indicate tha formation of X precedes formation of the acyl enzyme in the catalytic pathway. The data are compared to the similar results obtained with beta-trypsin and I* or I*-OMe.

Alanine↗
PubMed1978

New individual tissue compensators for high-energetic photons. Part I. Principle and procedure.

Part I. The inhomogeneity of absorbed dose caused by irregular body surface contour in the treatment port for external photon radiation is shown as a problem. The discussion of the physical fundamentals and technical possibilities of missing tissue compensators leads to a practical solution. A new handy procedure is presented allowing easy and rapid preparing of geometrically minified as well as absorption- and stray radiation corrected individual compensators. The achievable dose homogeneity within the target volume is shown as better than +/-5%. Systematical errors are investigated for the different parameters. In Part II systematical preclinical tests and first practical clinical experiences will be discussed.

Absorption↗
PubMed1978

[Possibilities, limitations and errors with ultrasound tomography in computer-assisted treatment planning (author's transl)].

Ultrasound tomography provides two-dimensional images, true in scale, of sonographic interfaces within nearly every sectional plane desired; it has become especially important, therefore, in irradiation planning. Complementary to results from a therapy simulator, an improvement in localization of tumor and target volume or of critical organs and of tissue inhomogeneities is possible. The hard-copy of gray-scale sonotomograms furnishes all essential geometric and anatomical input data needed for electronic systems used in irradiation planning. Technical, physical and diagnostic limitations of the method are stated. The possible systematic or technical-instrumental errors in sonographic treatment planning are discussed and the necessary calibration controls specified.

Abdomen↗
PubMed1978

[Homogenization of the dose to the target volume in case of irregular body-surface by means of compensation (author's transl)].

Irregular body-surface contours in the treatment part of high-energetic photon fields are producing an inhomogeneous dose distribution within the target volume. Homogenization of the dose is necessary in order to avoid over- or underdosage. A technique of making compensators is described. These are individual compensation filters substituting tissue layers which are lacking, they are correctly scaled down and optimally corrected in view of absorption and scattering according to the actual irradiation conditions. A simple mechanical device makes possible the production of a mould for heavy-metal compensators immediately in the course of scanning of the body-surface. A universal semi-automatic version of this method is appropriate to clinical practice; it records optically, and therefore without contact and quickly, all body-contours desired. By means of the image of moiré contour-lines thus obtained can be made the mould for the compensator in a second operation using an electronically controlled copy-milling machine.

Filtration↗
PubMed1976

[Importance of sonotomography in radiation therapy (author's transl)].

Ultrasound tomography provides true scale representation of body contours and organ structures. The image supplies substantial, individual geometrical data, essential for computerized radiation treatment planning. The mehtod is described. Typical planning examples for therapy are demonstrated. The value of follow up sonograms for radiation therapy is described. The limitations of the method are pointed out.

Humans↗