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Biomedical subjects

M Zankl

Publications and source records attributed to M Zankl.

At least 19 recordsLinked to original sources
PubMed1996

[Radiation exposure in interventional radiology as exemplified by the chemoembolization of hepatocellular carcinoma and laser angioplasty of the pelvic arteries].

PURPOSE: Estimation of radiogenic risks for patient and radiologist in chemoembolisation of hepatocellular carcinoma (HCC) and laser angioplasty of the pelvic arteries. METHODS: In 5 chemoembolisations of HCC (4 males, one female) and 6 laser angioplasties of the pelvic arteries (5 males, one female) the surface doses received by patient and operator were measured using thermoluminescent dosimeters in standardised positions. The organ doses of the patient were derived by conversion factors employed on the measured surface doses. Effective dose was determined according to the recommendations of ICRP 60. RESULTS: The risk of lethal malignant disease and genetic disorder derived from the doses in the patient was found to be of the magnitude of 10(-4)-10(-5). The thresholds for transient erythema of the skin and depression of hematopoiesis can be reached after high expositions. A theoretical maximum of 700 laser angioplasties of the pelvic arteries allowable in one year was calculated based on the dose to the operator's left hand. For chemoembolisation of HCC, the dose to the left eye lens would reach the yearly maximum after approximately 1000 procedures. Remarkable risks for malignant disease of skin and thyroid as well as detectable opacities of the eye lens can occur after frequent interventions for many years. CONCLUSIONS: Because of the lower life expectancy the patient's risk for stochastic effect can be seen as minimal. No clinically relevant deterministic effects will occur. In the case of frequent interventions, the dose absorbed by the radiologist is likely to exceed the prescribed dose limit and to cause remarkable risk for stochastic and non-stochastic effects after many years.

Aged↗
PubMed1995

An analysis of the equivalent dose calculation for the remainder tissues.

In the 1990 Recommendations of the International Commission on Radiological Protection, the risk-weighted quantity "effective dose equivalent" was replaced by a similar quantity, "effective dose." Among other alterations, the selection of the organs and tissues contributing to the risk-weighted quantity and their respective weighting factors were changed, including a modified definition of the so-called "remainder." Close consideration of this latter definition shows that it causes certain ambiguities and unexpected effects which are dealt with in the following. For several geometries of external photon irradiation, the numerical differences of two possible methods of evaluating the remainder dose from the doses to ten single organs, namely as arithmetic mean or as mass weighted average, are assessed. It is shown that deviation from these averaging procedures, as prescribed for those cases where a remainder organ receives a higher dose than an organ with a specified weighting factor, causes discontinuities in the energy dependence of the remainder dose and, consequently, also non-additivity of this quantity. These problems are discussed, and it is shown that, although the numerical consequences for the calculation of the effective dose are small, this unsatisfactory situation needs clarification. One approach might be to abolish some of the ICRP guidance relating to the appropriate tissue weighting factors for the remainder tissues and organs and to make other guidance more precise.

Adult↗
PubMed1993

Effective dose--how effective for patients?

The question discussed in this paper is whether effective dose can reflect the risk to patients from radiological procedures and can be used, for example, to optimise procedures and compare risks of various methods, to define dose constraints, and to estimate the risks to individuals or populations attributed to medical exposures. This report demonstrates that the use of effective dose for patients could be misleading or even wrong due to inappropriate simplifications of the underlying biological mechanisms and inappropriateness of the weighting factors connected with the definition of effective dose for a given patient population. We show that the choice of the most meaningful quantities to express patient exposure depends strongly on the respective situation.

Bone Marrow↗
PubMed1992

Effective dose and effective dose equivalent--the impact of the new ICRP definition for external photon irradiation.

In a recent recommendation, the International Commission on Radiological Protection substituted the effective dose equivalent, HE, with a similar quantity--the "effective dose," E--changing both the set of organs considered and the respective weighting factors. To quantify the impact of these changes, calculations of E and HE were performed for various photon energies and external irradiation geometries using a Monte Carlo code and mathematical anthropomorphic phantoms to which an esophagus was introduced for this purpose. For energies greater than 15 keV, E less than HE, the difference depending on photon energy and exposure geometry.

Female↗
PubMed1992

Spastic disorder in patients with hereditary multiple exostoses, but without spinal cord compression: a new syndrome?

We describe a 37 year old man with a history of a gait disorder which had been worsening over a period of three years. Clinical examination showed the typical signs of a spastic tetraparesis with increased tone of all the extremities. Sensation, autonomic and cerebellar functions were not disturbed. Multiple exostoses had been present since early childhood, but none had been found in the spine or the cranium to cause the tetraspastic disorder. MRI scan was normal. Pedigree analysis of four generations showed that other family members were affected by both disorders. Chromosomal analysis was normal. We consider this to be a previously unknown hereditary syndrome transmitted as an autosomal dominant and manifesting a combination of spastic tetraparesis and multiple exostoses.

Adult↗
PubMed1991

Mosaic tetraploidy in a liveborn infant with features of the DiGeorge anomaly.

We report on a liveborn male infant with mosaic tetraploidy who presented with multiple congenital anomalies including features of the DiGeorge anomaly (type I truncus arteriosus with other cardiovascular malformations, thymic hypoplasia, hypocalcemia). No structural chromosome aberrations, namely of chromosome 22, were detected. These findings contribute to the variability of symptoms of the polyploid phenotype. Additionally, the cytogenetic studies in our case emphasize the necessity of investigating fibroblasts in order to evaluate the relevant proportion of aberrant cells in mosaicism.

Abnormalities, Multiple↗
PubMed1988

The construction of computer tomographic phantoms and their application in radiology and radiation protection.

In order to assess human organ doses for risk estimates under natural and man made radiation exposure conditions, human phantoms have to be used. As an improvement to the mathematical anthropomorphic phantoms, a new family of phantoms is proposed, constructed from computer tomographic (CT) data. A technique is developed which allows any physical phantom to be converted into computer files to be used for several applications. The new human phantoms present advantages towards the location and shape of the organs, in particular the hard bone and bone marrow. The CT phantoms were used to construct three dimensional images of high resolution; some examples are given and their potential is discussed. The use of CT phantoms is also demonstrated to assess accurately the proportion of bone marrow in the skeleton. Finally, the use of CT phantoms for Monte Carlo (MC) calculations of doses resulting from various photon exposures in radiology and radiation protection is discussed.

Bone Marrow↗
PubMed1988

Organ doses from radionuclides on the ground. Part I. Simple time dependences.

Organ dose equivalents of mathematical, anthropomorphical phantoms ADAM and EVA for photon exposures from plane sources on the ground have been calculated by Monte Carlo photon transport codes and tabulated in this article. The calculation takes into account the air-ground interface and a typical surface roughness, the energy and angular dependence of the photon fluence impinging on the phantom and the time dependence of the contributions from daughter nuclides. Results are up to 35% higher than data reported in the literature for important radionuclides. This manuscript deals with radionuclides, for which the time dependence of dose equivalent rates and dose equivalents may be approximated by a simple exponential. A companion manuscript treats radionuclides with non-trivial time dependences.

Female↗
PubMed1984

[The long-eyelash syndrome (trichomegaly syndrome, Oliver-McFarlane)].

Two children with abnormally long eyelashes and bushy brows ("trichomegaly") present at birth and associated with pigmentary degeneration of the retina and general growth retardation are described. This combination of findings has been observed previously in three cases. Mental retardation, sparse scalp hair, endocrinologic deficiencies and (in one of our cases) koilonychia may be found in addition, but not necessarily.

Abnormalities, Multiple↗
PubMed1982

Cocultivation studies with cells of patients bearing fragile X chromosomes.

Fourteen cocultivation studies were carried out with cells of our patients with fragile X, one obligate and two possible female heterozygotes, two female controls, and a rabbit. In all cocultivations the number of fragile X chromosomes was sharply reduced in the patient cells. The strongest effect was causes by the animal cells. A distinct difference between the two controls in the reducing ability was observed. No such difference was found between the obligate and possible heterozygotes on the one hand and the controls on the other. To test the influence of the residual serum in the mixed blood cultures, the serum of a patient's blood sample was replaced by the serum of a control. The frequency of fragile X chromosomes was not decreased by this procedure. Therefore a soluble factor is supposed to exist which is produced by normal or heterozygote cells in culture and which reduces the expression of fragile sites in patient cells.

Animals↗
PubMed1982

Interstitial de novo deletion of the long arm of chromosome 5: mapping of 5q bands associated with particular malformations.

A new case of interstitial deletion of the long arm of one chromosome No. 5 (q13 leads to q22) is described. The girl shows mental retardation, severe hypotonia, dysmorphic facies and peculiar dermatoglyphics. The relationship between partial trisomies and partial monosomies of 5q chromosomal segments and associated clinical features is discussed. It seems possible to draw a rough phenotypic map of the long arm of chromosome 5 (5q), correlating observed malformations and phenotypic features with specific chromosomal regions.

Abnormalities, Multiple↗
PubMed1981

Dermatoglyphic peculiarities in Down's syndrome detection of mosaicism and balanced translocation carriers.

The combination of dermatoglyphic patterns and the number and intensity of traits characteristic for Down's syndrome can be statistically expressed by the "Walker" index and the "general" index. More than 96% of a Down's syndrome series and a control series could clearly be separated by the general index. Cytogenetic and dermatoglyphic features were studied in 17 patients with mosaic trisomy 21 and their parents. In the 17 cytogenetically diagnosed patients with mosaic Down's syndrome, a highly significant correlation was observed between the percentage of trisomic cells and the presence of traits characteristic for this syndrome in the dermatoglyphic patterns. The diagnostic problems and the value of dermatoglyphic examination in cases of mosaicism, where the trisomic cell line seems to have disappeared, is discussed. The results of our study also indicate an elevated incidence of a specific dermatoglyphic pattern combination with general index values similar to Down's syndrome in one parent in nearly 20% of Down's syndrome children. The possibility of hidden mosaicism in these parents of Down's syndrome children is discussed. Furthermore, the dermatoglyphic patterns in a large kindred with an inherited 15/21 translocation (21/41 carriers of the balanced translocation; 14/41 chromosomally normal; 6/41 mongoloid members) was analyzed. The data obtained from this translocation family and especially the values obtained in the general index indicate that some dermatoglyphic stigmata are directly associated with the D/21 translocation carrier state and can therefore be used for predicting this state.

Chromosomes, Human, 13-15↗
PubMed1981

New chromosomal dysmorphic syndromes. 4. Trisomy 12p.

This is the report of two independent families in which a balanced maternal translocation led to trisomy 12 p in one of each their offspring. Evaluation of 21 further case reports indicates that this is a phenotypically well defined syndrome which leads to severe developmental retardation. It can be recognized by a characteristic combination of craniofacial anomalies which are summarized in a phantom picture. The gene sequences which produce the typical features in the trisomic state must be localized distally to band 12p12, which is the breakpoint in the partial trisomies. The specific craniofacial anomalies are not visibly modified by the length of the trisomic segment or additional small monosomies or trisomies of recipient chromosomes. However, the frequency and severity of organ malformations and the resulting probability of survival seem to decrease with increasing degrees of chromosomal imbalance. A cytogenetic classification of the 21 inherited translocations and a segregation analysis from the pedigree data was performed. For the different types of translocations the calculated risk figures are given.

Chromosomes, Human, 6-12 and X↗