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At least 19 recordsLinked to original sources
PubMed1976

Evaluation and re-evaluation of genetic radiation hazards in man. III. Other relevant data and risk assessment.

Some of the advances in mammalian radiation genetics, human genetics and cytogenetics that were made during the last 2-3 years and that have either a direct bearing on, or that may be potentially useful in, the evaluation of genetic radiation hazards in man have been examined. Among these are (1) the new data on the incidence of genetic diseases in man; (2) the latest results of the study of mortality rates among children born to survivors of the atomic bombings of Hiroshima and Nagasaki; (3) new data on the radiation-induction of reciprocal translocations in human spermatogonia; (4) new results from radiation studies with mice on skeletal mutations, autosomal recessive lethals, sex-chromosome losses, translocation induction and recovery etc., and (5) a re-analysis of the earlier data on dose-rate effects for the induction of specific locus mutations in mouse spermatogonia. Using the pertinent new information as a basis, quantitative estimates are presented employing both a direct method of expressing risks in terms of effects per unit dose of irradiation and the indirect doubling-dose method of expressing these as increments over the load of genetic disorders occurring spontaneously in man.

Chromosome Aberrations↗
PubMed1976

Evaluation and re-evaluation of genetic radiation hazards in man. II. The arm number hypothesis and the induction of reciprocal translocations in man.

The arm number hypothesis proposed by Brewen and collagues in 1973 has been examined in the light of information thus far available from mammalian studies. In experiments with peripheral blood lymphocytes (radiation in vitro), a linear relationship between dicentric yield and the effective chromosome arm number of the species was obtained in the mouse, Chinese hamster, goat, sheep, pig, wallaby and man. However, the data are not consistent with such a relationship in several primate species (marmoset, rhesus monkey, cynomolgus monkey, squirrel monkey and the slow loris), the cat and the dog. In the rabbit, the data are conflicting. In the mouse and Chinese hamster the frequencies of reciprocal translocations recorded in spermatocytes descended from irradiated spermatogonia are in line with the expectation based on the arm number hypothesis, whereas in the golden hamster, rabbit and the rhesus monkey they are not. In man and the marmoset, the limited data are not inconsistent with a 2-fold higher sensitivity of these species relative to the mouse although they do not rule out a difference as high as 4-fold. In the guinea-pig, the situation is unclear. New data on the transmission of reciprocal translocations in mice suggest that the frequency in the F1 progeny may be close to one-quarter of that recorded in the spermatocytes of the irradiated fathers (spermatogonial irradiation) at an exposure level of 150 R, whereas at higher exposures, the reduction factor is about one-eighth, the latter being in line with the earlier finding. All these results taken together suggest that inter-specific extrapolation from the radiosensitivity of somatic cells (to dicentric induction) to that of germ cells (to translocation induction) is fraught with uncertainity at present. Certain aspects that need to be studied in more detail in the context of induced chromosome aberrations are discussed.

Animals↗
PubMed1976

[The mutagenic effect of x-rays iii. radiation genetic risks].

In the estimation of radiation genetic risks, the results must be derived from animal experiments. According to recently performed investigations, humans have almost the same mutation sensibility like mice. In risk estimations, it is necessary to take into account the factors which influence the mutation rate induced per unit dose. Risk estimations are carried out by comparing the effect per unit dose with the risk of the same effect, which is caused by unknown natural influences. The reader is reffered to data derived from humans.

Animals↗
PubMed1983

Failla Memorial Lectures. Radiation genetics: the mouse's view.

This report describes the lecturer's visit to Murinia where he consulted with the leading geneticists, including Dr. Maxie Mouse CXIV. The mice are greatly interested in the field of radiation genetics, but they no longer wish the honor of the major responsibility for setting our genetic radiation standards.

Animals↗
PubMed1986

Transposable genetic elements, spontaneous mutations and the doubling-dose method of radiation genetic risk evaluation in man.

The principal aspects of the 'doubling-dose method' currently used by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the Committee on the Biological Effects of Ionizing Radiation (BEIR) of the U.S. National Academy of Sciences, for the evaluation of genetic radiation hazards in man are briefly reviewed. With this method, which is primarily applicable to autosomal dominant and X-linked disorders, the expected increase in risk from radiation is expressed as a fraction of the current prevalence of these disorders, and thus in relation to an understandable frame of reference. Since the doubling dose is estimated as a ratio of spontaneous to induction rates of mutations, its magnitude is susceptible to changes in either the numerator (spontaneous rate) or the denominator (induction rate). Studies during the past 20 years or so with a number of experimental systems have demonstrated the existence of mobile DNA sequences in the genome and their causal role in the origin of spontaneous mutations, although the proportion of the latter among all spontaneous mutations is not known for any species. If a major proportion of spontaneous mutations in man is mediated by these mobile DNA sequences, and if their mobility is unaltered by radiation exposures, the calculation of the doubling dose in the manner mentioned above, and its use in risk evaluations becomes questionable. However, considerations based on the organization of the human genome would suggest that it is unlikely that a major fraction of spontaneous mutations that lead to disease states in man is due to mobile genetic elements. Consequently, the use of the doubling-dose method for the evaluation of genetic radiation hazards in man would appear to be valid at the present time.

Animals↗
PubMed1975

Estimation of the effects of chemical mutagens: lessons from radiation genetics.

Years of work with ionizing radiations have given us a wealth of data on radiation-induced mutations. These data, which have given insights regarding the mutational processes, should form the background for all mutagenesis work. In chemical mutagenesis, as in radiation mutagenesis, it is important to know the shape of the dose-effect curve in order to make further interpretations and calculations. It is also important to be on the constant alert for new relations that can be explored.

Animals↗
PubMed1986

Somatic and genetic radiation exposure of the patient in digital subtraction angiography (DSA)

The somatic and genetic radiation exposure of patients undergoing Digital Subtraction Angiography (DSA) and traditional Film Arteriography (FA) of cranial, cervical, thoracic and abdominal vascular territories are compared. The radiation doses absorbed within the critical organs--red bone marrow, lung, thyroid gland and female breast--and in the gonads were measured using an anthropomorphic Alderson phantom. A Somatic Dose Index was calculated in order to estimate the somatic radiation risk. The somatic radiation exposure depends upon the location of the critical organs with respect to the entrance site of the x-ray beam, and can be reduced by an appropriate choice of the angiographic projection. Under this condition, the radiation exposure of the patient during DSA can be lower than during FA. For renal DSA an a.p. projection, the use of an abdominal compression device and careful caudal shielding of the field are advocated.

Cerebrovascular Disorders↗