A multichannel feature-based approach for longitudinal lung CT registration in the presence of radiation induced lung damage

Quantifying parenchymal tissue changes in the lungs is imperative in furthering the study of radiation induced lung damage (RILD). Registering lung images from different time-points is a key step of this process. Traditional intensity-based registration approaches fail this task due to the considerable anatomical changes that occur between timepoints. This work proposes a novel method to successfully register longitudinal pre- and post-radiotherapy (RT) lung computed tomography (CT) scans that exhibit large changes due to RILD, by extracting consistent anatomical features from CT (lung boundaries, main airways, vessels) and using these features to optimise the registrations. Pre-RT and 12 month post-RT CT pairs from fifteen lung cancer patients were used for this study, all with varying degrees of RILD, ranging from mild parenchymal change to extensive consolidation and collapse. For each CT, signed distance transforms from segmentations of the lungs and main airways were generated, and the Frangi vesselness map was calculated. These were concatenated into multi-channel images and diffeomorphic multichannel registration was performed for each image pair using NiftyReg. Traditional intensity-based registrations were also performed for comparison purposes. For the evaluation, the pre- and post-registration landmark distance was calculated for all patients, using an average of 44 manually identified landmark pairs per patient. The mean (standard deviation) distance for all datasets decreased from 15.95 (8.09) mm pre-registration to 4.56 (5.70) mm post-registration, compared to 7.90 (8.97) mm for the intensity-based registrations. Qualitative improvements in image alignment were observed for all patient datasets. For four representative subjects, registrations were performed for three additional follow-up timepoints up to 48 months post-RT and similar accuracy was achieved. We have demonstrated that our novel multichannel registration method can successfully align longitudinal scans from RILD patients in the presence of large anatomical changes such as consolidation and atelectasis, outperforming the traditional registration approach both quantitatively and through thorough visual inspection.

Joint effects of pesticides and ultraviolet-B radiation on amphibian larvae

A combination of multiple stressors may be linked to global amphibian declines. Of these, pesticides and UVB radiation co-exposures were examined on the African clawed frog (Xenopus laevis) to provide information that may be useful for amphibian conservation. The independent action model and inferential statistics were used to examine interactions between pesticides (malathion, endosulfan, α-cypermethrin, or chlorothalonil) and environmentally relevant UVB exposures. UVB radiation alone caused 35-68% mortality and nearly 100% of malformations. Pesticides and UVB had additive effects on larval mortality; however, several non-additive effects (antagonistic and synergistic interactions) were observed for total body length. Insecticides mainly affected axial development, whereas UVB radiation caused high incidence of edema, gut malformations, and abnormal tail tips. These results suggest that sublethal developmental endpoints were more sensitive for detecting joint effects. This work has implications for amphibian risk assessments for ecosystems where pesticides and high UVB radiation may co-occur.

Management of dental complications in a child with rhabdomyosarcoma

Radiotherapy treatment options can cause adverse dental sequelae, including xerostomia, dental radiation caries, abnormal tooth development, and osteoradionecrosis (ORN). Hyperbaric oxygen (HBO) therapy can be used prophylactically or therapeutically to treat or reduce the risk of ORN. The purpose of this paper was to describe a case involving a 5-year-old male with rhabdomyosarcoma of the left temporal fossa and a history of radiation therapy who presented with gross radiation caries and xerostomia. Full-mouth extractions of all primary teeth were performed under general anesthesia, with the patient receiving HBO therapy before and after the surgery. The child was monitored postoperatively, and healing occurred with minimal post-operative complications. Based on his results, it can be concluded that hyperbaric oxygen therapy is an effective supplement to consider when treating children who have undergone radiation therapy and require dental care.

Pediatric neurological disorder and present nuclear detonation: a hot issue

It is no doubt for the health effect of the radiation from the nuclear detonation from the destroyed nuclear power plant. Due to the present crisis in Japan, the public health concern on this issue should be raised. In pediatric neurology, there are some interesting reports on pediatric neurological disorder and its relationship to leaked radiation. In this specific brief article, the author hereby discusses on the nuclear detonation and pediatric neurological disorder. Although there are some reports on the increased incidence of some pediatric neurological malignancies and congenital neurological anomalies there is no confirmed evidence. Effect on cognitive function is still controversial. The induction of abnormal electroencephalography is also mentioned. The observation on the effect of present crisis in pediatric neurology can provide more information and help better understand this topic.

Biological profiles of Korean atomic bomb survivors in residence at Daegu and Kyungbuk, Republic of Korea

In 1945, many Koreans, in addition to Japanese, were killed or injured by the atomic bombs dropped on Hiroshima and Nagasaki, Japan. This study compared the biological profiles of Korean atomic bomb survivors in residence at Daegu and Kyungbuk, Republic of Korea with those of a representative sample of Koreans obtained during a similar period. We evaluated anthropometric measurements, blood pressure, blood cell counts, blood chemistry, and urinalysis of survivors (n=414) and age- and sex-matched controls (n=414) recruited from the third Korea National Health and Nutrition Examination Survey conducted in 2005. Univariate analyses revealed significantly higher systolic blood pressure, white blood cell count, and serum total cholesterol, triglycerides, high-density lipoprotein-cholesterol, and aspartate aminotransferase levels (p<0.01) in the survivors. Conversely, hemoglobin concentration, hematocrit, red blood cell count, and the proportion of positive urine occult blood (p<0.01) were lower in the survivors. Our findings suggest that biological profiles of Korean atomic bomb survivors were adversely affected by radiation exposure.

Lauriston S. Taylor lecture: fifty years of scientific research: the importance of scholarship and the influence of politics and controversy

Over the past 50 years our laboratory has performed and published many studies in the fields of teratology, radiation biology and radiation embryology. The early work took place when I was a research employee at the University of Rochester Manhattan Project in 1944 and where I had my introduction to embryology and genetics. Over the years our lab has provided consultations dealing with the risks of various environmental toxicant exposures during pregnancy. With the advent of the Internet, consulting has become more rapid and efficient. In the past year our pregnancy Web site of the Health Physics Society received approximately 154,000 hits, of which over a thousand contacts were still quite anxious after reading the Web site answers and requested a personal consultation. From this extensive experience we have learned that many physicians and other counselors are not prepared to counsel patients concerning radiation risks. Approximately 8% of the patient contacts who have consulted a professional have been provided with inaccurate information that would have resulted in an unnecessary interruption of a wanted pregnancy. There are five areas of radiation embryology that are considered to be controversial. 1) Can the fetus be harmed by ionizing radiation if the fetus is not directly exposed? 2) Is the production of mental retardation from radiation during pregnancy a threshold phenomenon? 3) Does fractionation and protraction of radiation decrease the magnitude of the reproductive and developmental risks? 4) Is there a period during pregnancy when radiation will result in an increased mortality but not an increase in malformations? 5) How sensitive is the fetus to the oncogenic effects of radiation? We utilize the scientific information obtained from studies in these five areas to counsel patients concerning pregnancy radiation risks. The willingness and persistence of scientists to debate the controversial aspects of this research and apply the best available scientific information to assist patients in turmoil about the risks of radiation to themselves and their offspring has saved thousand of lives and changed family histories.

Proximal femoral focal deficiency as a manifestation of Antley-Bixler syndrome: a case report

We report a case of the Antley-Bixler syndrome in an 11-year-old girl. She presented with bilateral proximal femoral focal deficiency, right clubfoot, left radiohumeral synostosis, bilateral ear hypoplasia, cleft palate, tongue tie, missing teeth, congenital heart disease, a pelvic kidney with hydronephrosis, and mental retardation. Proximal femoral focal deficiency has never been reported before as a manifestation of Antley-Bixler syndrome. Her mother was exposed to radiation during an intravenous urogram done in the first trimester of pregnancy. Exposure to radiation has not been implicated as a cause of Antley-Bixler syndrome.

[Effects of exposure to extremely low frequency electromagnetic fields on reproduction of female mice and development of offsprings]

OBJECTIVE

To observe the effects of exposure to extremely low frequency electromagnetic fields (ELF EMFs) on pregnant mice and development of offsprings.

METHODS

Female mice were exposed to 50 Hz, 1.2 mT electromagnetic fields during the whole pregnant period (8 h/d). The body weight of dams, delivery and development of offsprings were observed and measured.

RESULTS

The increase of body weight of exposed dams (29.0%) was significantly slower than that of the control group (47.8%) during late pregnancy period (P < 0.05). The producing rate of exposed group was 60% of that of control group. Miscarriage, fetal loss and externally malformed fetus appeared in exposed group. The average number of offsprings of each exposed mouse was significantly decreased (11 +/- 1.6 vs 7 +/- 2.0, P < 0.05) and 11 for control group. Regarding the development of offspring, the body weight of prenatally exposed offsprings was increased more slowly than that of the control in the first two weeks after birth (P < 0.05). Developmental manifestations including eye opening [(252 +/- 24) h] and tooth eruption [(336 +/- 19) h] presented later in exposed offspring [(226 +/- 12), (319 +/- 15) h, respectively] (P < 0.05).

CONCLUSION

Exposure to ELF EMFs during pregnancy period can cause adverse effects on pregnancy of female mice and development of offsprings.

Non-cancer diseases of Korean atomic bomb survivors in residence at Hapcheon, Republic of Korea

Many Koreans, in addition to Japanese, were killed or injured by the atomic bombs detonated over Hiroshima and Nagasaki, Japan, in 1945. Our study examined noncancer diseases of Korean A-bomb survivors in residence at Hapcheon, Republic of Korea and evaluated whether they had significantly higher prevalence of noncancer diseases than non-exposed people. We evaluated a number of tests, including anthropometric measurements, blood pressure, blood chemistry, hepatitis B surface antigen, and urinalysis, of survivors (n=223) and controls (n=372). Univariate analysis revealed significantly lower fasting glucose and creatinine, and higher diastolic blood pressure, aspartate aminotransferase, alanine aminotransferase, and blood urea nitrogen levels in the survivors than in the controls. The calculation of crude prevalence ratios (PRs) revealed that A-bomb survivors had a significantly higher prevalence of hypertension (PR, 1.16; 95% CI, 1.00-1.35) and chronic liver disease (2.20; 1.59-3.06) than controls. After adjusting for covariates (age, sex, body mass index, marital status, education, alcohol consumption, and smoking), A-bomb survivors had a significantly higher prevalence of hypertension (1.24; 1.06-1.44), chronic liver disease (2.07; 1.51-2.84), and hypercholesterolemia (1.79; 1.11-2.90) than controls. This study suggests that A-bomb exposure is associated with a higher prevalence of non-cancer diseases in Korean survivors.

Clinical validation of the LKB model and parameter sets for predicting radiation-induced pneumonitis from breast cancer radiotherapy

The choice of the appropriate model and parameter set in determining the relation between the incidence of radiation pneumonitis and dose distribution in the lung is of great importance, especially in the case of breast radiotherapy where the observed incidence is fairly low. From our previous study based on 150 breast cancer patients, where the fits of dose-volume models to clinical data were estimated (Tsougos et al 2005 Evaluation of dose-response models and parameters predicting radiation induced pneumonitis using clinical data from breast cancer radiotherapy Phys. Med. Biol. 50 3535-54), one could get the impression that the relative seriality is significantly better than the LKB NTCP model. However, the estimation of the different NTCP models was based on their goodness-of-fit on clinical data, using various sets of published parameters from other groups, and this fact may provisionally justify the results. Hence, we sought to investigate further the LKB model, by applying different published parameter sets for the very same group of patients, in order to be able to compare the results. It was shown that, depending on the parameter set applied, the LKB model is able to predict the incidence of radiation pneumonitis with acceptable accuracy, especially when implemented on a sub-group of patients (120) receiving [see text]|EUD higher than 8 Gy. In conclusion, the goodness-of-fit of a certain radiobiological model on a given clinical case is closely related to the selection of the proper scoring criteria and parameter set as well as to the compatibility of the clinical case from which the data were derived.

Diagnostic Radiation in Pregnancy: Perception Versus True Risks

Significant numbers of therapeutic abortions are performed for radiation-exposed pregnant women because of concerns about the teratogenic risk. However, available data suggest that current diagnostic radiation procedures are not teratogenic.

Telomere shortening is associated with malformation in p53-deficient mice after irradiation during specific stages of development

The natural ends of linear chromosomes, the telomeres, recruit specific proteins in the formation of protective caps that preserve the integrity of the genome. Unprotected chromosomes induce DNA damage checkpoint cascades and ultimately lead to senescence both in mouse and man in a p53 dependent manner and initial telomere length setting therefore determines the proliferative capacity of each cell. Yet, only little information is available on telomere biology during embryonic development. We have previously shown that the p53 gene plays a crucial role in the development of malformations (exencephaly, gastroschisis, polydactyly, cleft palate and dwarfism) in control and irradiated mouse embryos. Here, we investigated telomere biology and the outcome of radiation exposure in wild type (p53+/+) and p53-mutant (p53+/-- and--/--) C57BL mouse foetuses irradiated at three different developmental stages. We show that telomeres are significantly shorter in malformed foetuses as compared to normal counterparts. In addition, our results indicate that the observed telomere attrition is primarily associated with p53-deficiency but is also modulated by irradiation, more specifically during the gastrulation and organogenesis stages. In conclusion, we formulate a hypothesis in which telomere shortening is linked to the absence of p53 in mouse foetuses and that when, in the presence of shorter telomeres, these foetuses are irradiated, the chance for the occurrence of developmental defects increases substantially.

Effects of Prenatal Irradiation with an Accelerated Heavy-Ion Beam on Postnatal Development in Rats: I. Neurophysiological Alterations

Effects on postnatal neurophysiological development in offspring were studied after exposure of pregnant Wistar rats to accelerated carbon-ion beams with an LET of about 13 keV/ mum at doses ranging from 0.1 Gy to 2.5 Gy on the 15th day of gestation. The age at which four physiological markers appeared and five reflexes were acquired was examined prior to weaning. Gain in body weight was monitored until the offspring were 3 months old. Male offspring were evaluated as young adults using two behavioral tests. The effects of X rays estimated for the same biological end points were studied for comparison. For most of the end points at early age, no significant alterations were observed in offspring that received prenatal irradiation with 0.1 Gy of either accelerated carbon ions or X rays compared to the offspring of sham-irradiated dams. However, all offspring whose dams received 2.5 Gy died prior to weaning. Offspring from dams irradiated with accelerated carbon ions generally showed higher incidences of prenatal death and preweaning mortality, markedly delayed accomplishment in their physiological markers and reflexes, and gain in body weight compared to those exposed to X rays at doses of 0.5 to 2 Gy. Significantly reduced ratios of main organ weight to body weight at the postnatal ages of 30, 60 and 90 days were also observed within this dose range. The results indicate that irradiation with 0.5 to 2 Gy on day 15 of gestation caused permanent alterations in offspring that were dependent on dose. The alterations include permanent growth retardation, morphological malformations in main organs, including microcephaly, diminished reflex attainment, delayed appearance of physiological markers, and changes in adult behavior. Exposure to 1 to 2 Gy of radiation resulted in growth retardation and behavioral alterations that persisted throughout life. Accelerated carbon ions generally induced more detrimental effects than X rays.

Ionizing radiations in pregnancy and teratogenesis: a review of literature

The present paper is a review of the data available in the literature concerning the prenatal exposure to radiation evaluating the reported teratogenic effect. We have particularly focused on the fetal effects of maternal ionising radiation exposure, both diagnostic and occupational, particularly in terms of congenital anomalies and birth weight. Ionising radiation represents a possible teratogen for the fetus, but this risk has been found to be dependent on the dosage and the effects correlatable to the gestational age at exposure. Recently, of particularly note is the fact that maternal thyroid exposure to diagnostic radiation has been associated with a slight reduction in the birth weight. Inadvertent exposure from diagnostic procedures in pregnancy doesn't usually increase the natural risk of congenital anomalies but creates a considerable state of maternal anxiety. Diagnostic radiological procedures should be avoided in pregnant women unless the information cannot be obtained by other techniques.

Radioadaptive response for protection against radiation-induced teratogenesis

To clarify the characteristics of the radioadaptive response in mice, we compared the incidence of radiation-induced malformations in ICR mice. Pregnant ICR mice were exposed to a priming dose of 2 cGy (667 muGy/min) on day 9.5 of gestation and to a challenging dose of 2 Gy (1.04 Gy/min) 4 h later and were killed on day 18.5 of gestation. The incidence of malformations and prenatal death and fetal body weights were studied. The incidence of external malformations was significantly lower (by approximately 10%) in the primed (2 cGy + 2 Gy) mice compared to the unprimed (2 Gy alone) mice. However, there were no differences in the incidence of prenatal death or the skeletal malformations or the body weights between primed and unprimed mice. These results suggest that primary conditioning with low doses of radiation suppresses radiation-induced teratogenesis.

Effects of carbon-ion radiation on the postnatal development of mice and on the yield of white spots in the mid-ventrum and tail tips

Pregnant female C57BL/10JHir mice were irradiated whole-body at 9 days of gestation with a single acute dose of carbon-ion radiation. The average linear energy transfer (LET) of the carbon ions was 50 keV/microm within a spread-out Bragg peak (SOBP). The effects were studied by scoring changes in the postnatal development of the mice as well as in the pigmentation of the cutaneous coats and tail tips of their offspring 22 days after birth. The percentage of live births was reduced in mice exposed to carbon ions at doses greater than 0.5 Gy. The survival to day 22 was also reduced in mice exposed to carbon ions at doses greater than 0.75 Gy. Moreover, the body weight at day 22 was reduced in mice exposed to carbon ions at doses greater than 0.1 Gy. A comparison of the survival to day 22 after exposure to carbon ions with our previous results for 60Co gamma rays indicated that carbon ions were twice as effective as gamma rays. White spots were found in the mid-ventrum as well as in the tail tips of offspring exposed to carbon ions in utero. The frequency and the size of the white spots in the mid-ventrum and in the tail tips increased as the dose increased. Carbon ions appear to be slightly more effective than the gamma rays used in our previous study. In the ventral white spots, no melanocytes were observed in the epidermis, dermis and hair follicles. These results indicate that prenatal exposure to carbon ions has a greater effect on the postnatal development and survival of mice than does exposure to gamma rays, and that the relative biological effectiveness is greater than that for effects on melanocyte development.

Transgenerational genomic instability as revealed by a somatic mutation assay using the medaka fish

We previously established a somatic mutation assay of the medaka wl (white leucophores) locus based on visual inspection, and showed that somatic mutations at paternally derived alleles frequently arise during the development of F1 embryos fertilized by sperm/late spermatids that had been exposed to gamma-rays. To further study such delayed mutations, we determined the frequency of mutant embryos obtained from three different crosses between irradiated males and non-irradiated females. When sperm and late spermatids were irradiated, the mutant frequency within non-irradiated maternally derived alleles was approximately 3 times higher than in the control group. In the F2 generation, however, no increase in mutant frequency was observed. Similarly, there was no significant increase in the F1 mutant frequency when stem spermatogonia were irradiated. These data suggest that irradiation of sperm and late spermatids can induce indirect mutations in F1 somatic cells, supporting the idea that genomic instability arises during F1 embryonic development. Moreover, such instability apparently arises most frequently when eggs are fertilized just after the sperm are irradiated.

Biological effects after prenatal irradiation (embryo and fetus). A report of the International Commission on Radiological Protection

In its 1990 recommendations, the ICRP considered the radiation risks after exposure during prenatal development. This report is a critical review of new experimental animal data on biological effects and evaluations of human studies after prenatal radiation published since the 1990 recommendations.Thus, the report discusses the effects after radiation exposure during pre-implantation, organogenesis, and fetogenesis. The aetiology of long-term effects on brain development is discussed, as well as evidence from studies in man on the effects of in-utero radiation exposure on neurological and mental processes. Animal studies of carcinogenic risk from in-utero radiation and the epidemiology of childhood cancer are discussed, and the carcinogenic risk to man from in-utero radiation is assessed. Open questions and needs for future research are elaborated. The report reiterates that the mammalian embryo and fetus are highly radiosensitive. The nature and sensitivity of induced biological effects depend upon dose and developmental stage at irradiation. The various effects, as studied in experimental systems and in man, are discussed in detail. It is concluded that the findings in the report strengthen and supplement the 1990 recommendations of the ICRP.

Implications of research in male-mediated developmental toxicity to clinical counsellors, regulators, and occupational safety officers

In closing, let me return to the somewhat irreverent question that I asked at the beginning: Apart from what we learn about fundamentally important biological processes, does male-mediated developmental toxicity make any practical difference? The answer is no, yes, and we don't know. No: The risk of serious birth defects in the future children of a man who is concerned about exposure to radiation or chemicals in the remote past does not appear to be measurably increased in comparison to the background. Yes: Male-mediated developmental toxicity may be of sufficient concern to restrict certain exposures in the population as a whole, but in order for male-mediated developmental toxicity to be determinative, these conditions will have to be otherwise non-toxic. To date, no exposures have been identified that produce substantial male-mediated developmental toxicity in the complete absence of other kinds of toxicity. We don't know how big a problem male-mediated developmental toxicity really is because we have not studied a large enough number and variety of exposures. We don't know if our perspective will change as we begin to understand the importance of individual susceptibility better. We don't know all of the mechanisms that may be involved in male-mediated developmental toxicity or their general biological importance. We don't know more than we do know about male-mediated developmental toxicity, and we are anxious to learn more.

Radiation and malformations in a murine model

Thus, the results of radiation exposure of the different stages of spermatogenesis with regard to the induction of malformations in the offspring of these exposed male mice can be summarized as follows: It is possible to induce malformations in the offspring by radiation exposure of male mice of the HLG strain. This means that direct DNA damage is responsible for the induction of the observed malformations. The highest sensitivity is observed during meiosis. The fact that direct DNA damage is involved in the induction of radiation induced malformations underlines the hypothesis mentioned above, that two processes may have a major impact on malformation induction in germ cells and preimplantation stages: 'genetic predisposition' and 'genomic instability'.

Effects of power frequency alternating magnetic fields on reproduction and pre-natal development of mice

Three groups of ICR male and female mice were exposed to 50-Hz, sinusoidal, alternating, horizontal magnetic fields of 0.0 mT (sham), 0.5 mT and 5.0 mT (rms) for 9 and 2 weeks prior to mating for males and females, respectively, through fertilization and until cesarean sectioning. Fetuses were collected by cesarean section on the 18th day of gestation. Approximately half were randomly selected for skeletal examination and the remainder used for visceral examination. No significant differences were found between the field- and the sham-exposed groups in pre-, post- and total implantation losses; number of live fetuses; sex ratio; live fetal weight; number of externally abnormal fetuses; and numbers of fetuses with skeletal and visceral anomalies. These results suggest that exposure to power-frequency magnetic fields has no major effects on reproduction and development in mice, and do not support the association of EMF exposure with adverse reproductive effects suggested by epidemiology.

Combined effects of radiation and ultrasound on ICR mice in the preimplantation stage

Embryos of ICR mice at the preimplantation stage of development were used to examine the single and combined effects of ultrasound (US) and radiation. Pregnant mice were exposed to a single dose of whole body gamma radiation and/or US at 2 hpc (hours postconception) or 3 hpc. The exposure duration was 10 min with 1-MHz continuous wave US at 1 or 2 W/cm(2) by I(SPTA) (intensities of spatial peak temporal average). Gamma irradiation of pregnant mice (2 hpc) was at 0.5 Gy at a dosage rate of 0.2 Gy/min. The rate for ultrasonic irradiation was a dose of 1 or 2 W/cm(2), considered by some to be too high in therapy, such as for arthritis in the rehabilitation area of the medical application. Various malformations were recognized, and the incidence of malformations in the 0.5-Gy exposure and the control groups were compared. A greater number of malformations were observed in the 0.5-Gy exposure group relative to the 0.5-Gy plus 1.0 W/cm(2) US exposure group. Therefore, the synergistic effects of radiation relate to external malformations, the number of implantations, and the rate of embryonic death due to US. It appears that US may act to repair DNA damaged by ionizing radiation. The cell cycle of the fertilized egg is delayed, which may be the mechanism by which lesions induced by ionizing radiation are healed by ultrasonic irradiation.

Radiobiological results of the Biostack experiment on board Apollo 16 and 17

After penetrating the Biostack capsule, some of the HZE particles hit the biological objects carried: bacterial spores (Bacillus subtilis), seeds (Arabidopsis thaliana and Vicia faba), and shrimp eggs (Artemia salina). The different biological objects were affected by heavy ions in widely varying ways. A broad range of radiobiological investigations has been carried out in regard to the objects' response to HZE particles. The most sensitive biological objects in the Biostack experiments proved to be the shrimp eggs. The development of 500 eggs hit by heavy cosmic ions was investigated. This differed significantly from the flight controls (eggs flown in the Biostack but not hit by heavy ions) and from the ground controls. From this it has been concluded that penetration on the part of a single heavy ion may injure the encysted blastula. This damage was found to influence gastrula formation and even the hatching process of the nauplius. Abnormalities (increased by a factor of 10) in the orthonauplius were observed during the development of the hit eggs; they consisted, for example, of shortened extremities or an abnormal thorax or abdomen. In addition, eggs of Tribolium confusum and Carausius morosus, which were included in Biostack 2 (Apollo 17), have been investigated, and the influence of single heavy ions on the development process of these highly organized insects has been studied.

Developmental abnormalities induced by X-irradiation in p53 deficient mice

In order to assess the influence of p53 inactivation on radiation-induced developmental effects, male mice heterozygous for the wild-type p53 allele (mimicking the human Li-Fraumeni syndrome) were crossed with C57BL females, and their heterozygous p53+/- progeny were mated with each other to obtain p53+/-, p53-/- and p53+/+ embryos. Pregnant females were X-irradiated with 0.5 Gy on days 1 (pre-implantation period), 8 or 11 (organogenesis period) of gestation. Dissection of the pregnant females occurred on day 19 of gestation. The p53 genotype of the foetuses was determined by PCR from small pieces of soft tissues. Exencephaly was the only external malformation found in the control group. It affected essentially p53-/- female foetuses. A number of p53+/- and p53+/- control foetuses also showed dwarfism, or underdevelopment. In the group irradiated on day 1, the frequency of abnormal foetuses was, paradoxically, lower than that found in the control group. As in that group, exencephaly and dwarfism constituted the only anomalies that were found. Exencephaly affected only homozygous p53-/- females, while dwarfism concerned either p53-/- or p53+/- foetuses, with a majority of females. Irradiation on day 8 of gestation induced a significant increase in the frequency of abnormal foetuses, compared to the control group. Various malformations were observed in addition to exencephaly, including gastroschisis, polydactyly, cephalic oedema and cleft palate. All malformed foetuses were either homozygous p53-/- or heterozygous p53+/- while most affected foetuses were females, as was the case for dwarf individuals. Irradiation on day 11 did not cause an increase in the frequency of abnormal foetuses, in comparison with the controls. However, a large spectrum of external malformations was again noticed, as in the group irradiated on day 8. All affected foetuses were homozygous p53-/- and there were slightly more abnormal females than males (3 out of 5). No dwarfs were found in this group. Overall, these results confirm the importance of the p53 tumour-suppressor protein for normal embryonic development. They clearly show that homozygous p53-/- (or heterozygous p53+/- to a lesser extent) foetuses are more at risk for radiation-induction of external malformations during the organogenesis period, and that the risk of developing such malformations is much higher for females than for males. In contrast to results published very recently by others, we found that malformed foetuses resulting from an X-irradiation with a low-dose during the highly sensitive period of gastrulation are able to survive to birth.

[Pregnancy and medical irradiation; summary and conclusions from the International Commission on Radiological Protection, Publication 84]

Prenatal exposure to ionising radiation as used during most diagnostic procedures generally presents no increased risk of prenatal death, malformation or impairment of mental development (i.e. deterministic effects) compared to the background incidence of these entities. Higher doses of radiation used in therapeutic procedures can result in significant foetal harm. In general, malformations only occur above a threshold dose of 100-200 mGy. These doses are not normally reached with most properly executed diagnostic procedures. During the period from 8 to 25 weeks after conception, the central nervous system is particularly sensitive to radiation. Foetal doses in excess of about 100 mGy may result in a decrease in IQ. Between 8-15 weeks after conception, a foetal dose of 1000 mGy (1 Gy) reduces IQ by about 30 points. This reduction is less marked during the period from 16-25 weeks. At foetal doses of 1000 mGy in the period from 8 to 15 weeks after conception the risk of severe mental retardation is about 40%. During the period from 16 to 25 weeks, this risk is practically zero at a dose of 1000 mGy. Radiation exposure of the embryo/foetus is associated with an increased risk of tumour induction (stochastic effect). Recent absolute risk estimates for fatal cancer risk for ages 0-15 year after in utero irradiation have been estimated to be 6% per Gy (0.06% per 10 mGy). For the whole life span this risk is about 15% per Gy (0.15% per 10 mGy). Pre-conception irradiation of either parent's gonads has not been shown to result in increased cancer or malformations in the children.

Model prediction of treatment planning for dose-fractionated radioimmunotherapy

BACKGROUND

Clinical trials of radioimmunotherapy (RIT) often use dose fractionation to reduce marrow toxicity. The dosing scheme can be optimized if marrow and tumor cell kinetics following radiation exposure are known.

METHODS

A mathematic model of tumor clonogenic cell kinetics was combined with a previously reported marrow cell kinetics model that included marrow stromal cells, progenitor cells, megakaryocytes, and platelets. Reported values for murine tumor and marrow cellular turnover rates and radiosensitivity were used in the model calculation.

RESULTS

Given a tolerated level of thrombocytopenia, there is a fractionation scheme in which total radioactive dose administration can be maximized. Isoeffect doses that had different numbers of fractions and total radioactivity, but induced identical platelet nadirs of 20%, were determined. Assuming identical tumor uptake for all dose fractions, six tumor types were examined: early-responding tumors, late-responding tumors, and tumors that lacked a late-responding effect, with either constant or accelerated doubling time. For most tumor types, better tumor control (tumor growth delay and nadir of survival fraction) was predicted for a dosing scheme in which total radioactive dose was maximized. For late-responding tumors with accelerated doubling time, tumor growth delay increased, but the nadir of survival fraction became shallower as the number of fractions increased.

CONCLUSIONS

A mathematic model has been developed that allows prediction of the nadir and duration of thrombocytopenia as well as tumor clonogenic cell response to various RIT doses and fractionation schemes. Given a maximum tolerated level of thrombocytopenia, the model can be used to determine a dosing scheme for optimal tumor response.

Reproductive and developmental toxicity of natural and depleted uranium: a review

Although the biokinetics, metabolism, and chemical toxicity of uranium are well known, until recently little attention was paid to the potential toxic effects of uranium on reproduction and development in mammals. In recent years, it has been shown that uranium is a developmental toxicant when given orally or subcutaneously (SC) to mice. Decreased fertility, embryo/fetal toxicity including teratogenicity, and reduced growth of the offspring have been observed following uranium exposure at different gestation periods. The reproductive toxicity, maternal toxicity, embryo/fetal toxicity, and postnatal effects of uranium, as well as the prevention by chelating agents of uranium-induced maternal and developmental toxicity are reviewed here. Data on the toxic effects of depleted uranium on reproduction and development are also reviewed.

Developmental toxicity interactions of methanol and radiofrequency radiation or 2-methoxyethanol in rats

This research was undertaken to determine potential interactions among chemical and physical agents. Radiofrequency (RF) radiation is used in numerous workplaces, and many workers are concurrently exposed to RF radiation and various chemicals. The developmental toxicity of RF radiation is associated with the degree and duration of hyperthermia induced by the exposure. Previous animal research indicates that hyperthermia induced by an elevation in ambient temperature can potentiate the toxicity and teratogenicity of some chemical agents. We previously demonstrated that combined exposure to RF radiation (10 MHz) and the industrial solvent, 2-methoxyethanol (2ME), enhanced teratogenicity in rats. Interactions were noted at even the lowest levels of 2ME tested, but only at hyperthermic levels of RF radiation. The purpose of the present research is to investigate if the interactive effects noted for RF radiation and 2ME are unique to these agents, or if similar interactions might be seen with other chemicals. Because methanol is widely used as a solvent as well as fuel additive, and, at high levels, is teratogenic in animals, we selected methanol as a chemical to address generalizability. Based on the literature and our pilot studies, 0, 2, or 3 g/kg methanol (twice, at 6-hour intervals) were administered on gestation day 9 or 13 to groups of 10 Sprague-Dawley rats. Dams treated on day 9 were given methanol and exposed to RF radiation sufficient to maintain colonic temperature at 41 degrees C for 60 minutes (or sham). Those treated on day 13 were given methanol plus either 0 or 100 mg/kg 2ME. Because we observed that methanol produced hypothermia, some groups were given the initial dose of methanol concurrently with the RF or 2ME, and others were given the first dose of methanol 1.5 hours prior to RF or 2ME. Dams were sacrificed on gestation day 20, and the fetuses were examined for external malformations. The results indicate that RF radiation or methanol on day 9 increased the incidence of resorbed fetuses, but no interactive effects were observed. The resorptions were highest in groups given the experimental treatments 1.5 hours apart. The higher dose of methanol also reduced fetal weights. Administration of 2ME or methanol on day 13 increased the rate of malformations, and there was evidence of a positive interaction between 2ME and methanol. Fetal weights were reduced by 2ME and methanol alone, but no interaction was observed. Also, separation of the dosing with the teratogens did not affect the results. These results point out that interactions in developmental toxicology, such as those of RF radiation, 2ME, and methanol that we have studied, are complex, and such interactions cannot be fully understood or predicted without more research. It is important that combined exposure effects be considered when developing both physical agent and chemical agent exposure guidelines and intervention strategies.

Effects on ontogenesis of Carausius morosus hit by cosmic heavy ions

Among the biological problems that arise in long duration spaceflights, the effects of weightlessness and ionizing radiation appear to be the two main risk factors. Eggs of the stick insect Carausius morosus were exposed to spaceflight conditions during the 12.56 day Biosatellite mission Cosmos 1887. Five different ages were used, representing different sensitivities to radiation and different capacities for regeneration. During spaceflight the eggs continued their development. Already, in the Spacelab D1 mission in 1985, it has been shown that microgravity leads to a reduced hatching rate of eggs exposed during the early steps of development. When the eggs were hit by a heavy ion, a further but not significant reduction of the hatching rate was observed. Hatching was normal for eggs which were exposed on a 1 g reference centrifuge in space. Heavy ion hits caused body anomalies. The combined action of heavy ions and microgravity resulted in an unexpectedly high rate of anomalies. In the experiment on Cosmos 1887 these results were confirmed. Studies on the embryonic development before hatching showed no major difference between flight and ground control specimen, neither in speed of development nor in morphological anomalies. Hatching therefore seems to be the critical point in insect ontogenesis.

[Evolution of the ideas on genetic hazards of ionizing radiation in humans]

Based on the reports of UNSCEAR for the period from 1958 to 2001 the paper presents a retrospective analysis of the use of direct methods and the doubling dose method for quantitative determination of the genetic risk of human exposure expressed as different hereditary diseases. As early as 1962 UNSCEAR estimated the doubling dose (a dose causing as many mutations as those occurring spontaneously during one generation) at 1 Gy for cases of exposure to ionizing radiations with low LET at a low dose rate and this value was confirmed in the next UNSCEAR reports up to now. For cases of acute irradiation the doubling dose was estimated at 0.3-0.4 Gy for the period under review. The paper considers the evolution of the concepts of human natural hereditary variability which is a basis for assessing the risk of exposure by the doubling dose method. The level of human natural genetic variability per 1,000,000 newborns is estimated at 738,000 hereditary diseases including mendelian, chromosomal and multifactorial ones. The greatest difficulties in assessing the doubling dose value were found to occur in the case of multifactorial diseases the phenotypical expression of which depends on mutational events in polygenic systems and on numerous environmental factors. The introduction in calculations of the potential recoverability correction factor (PRCF) made it possible to assess the genetic risk taking into account this class of hereditary diseased. The current estimate of genetic risk is 3000-4700 genetic diseases in the first generation per 1,000,000 newborns after exposure of the parental generation to 1 Gy at low dose rate. A certain part of genetic changes after exposure of the parental generation to radiation will express themselves in the second generation, in grandchildren (1150-3200 cases or 56% of the effect predicted for the first generation), and in succeeding generations.

[Cranial irradiation induces premature activation of the gonadotropin-releasing-hormone]

BACKGROUND

CNS-irradiation in prepubertal children with leukemia or brain tumors can lead to precocious or in high doses to delayed puberty. The underlying mechanisms of these disorders are unknown.

METHODS

A new animal model of experimentally induced pubertal disorders by cranial irradiation has been developed. In infantile or juvenile (12 - 23 days old) female rats precocious or delayed puberty have been induced by selective cranial Co60-irradiation (4 - 18 Gy). At age of 32 - 38 days or 3 months relevant hormone parameters have been studied basal and after stimulated conditions.

RESULTS

Low radiation doses (5 or 6 Gy) led to accelerated onset of puberty as well as elevated LH- and estradiol levels. High radiation doses (9 - 18 Gy) caused retardation of sexual development, lower gonadotropin levels and growth retardation associated with growth hormone deficiency. After cranial irradiation with 5 Gy the release rates of the inhibitory neurotransmitter gamma-aminobutyric-acid (GABA) from hypothalamic explants were significantly lower (p < 0,05). The gonadotropin-releasing-hormone (GnRH) expression in the hypothalamic preoptic area of irradiated animals (5 Gy) was significantly higher than in controls (p < 0,05).

CONCLUSION

The GnRH-pulse generator is very radiosensitive as low dose irradiation causes precocious puberty, whereas high dose irradiation is associated with delayed sexual maturation. Radiation induced precocious puberty might be caused by damage to inhibitory GABAergic neurons leading to desinhibition and premature activation of GnRH neurons. Our animal model of cranial irradiation seems to be suitable to study neurotransmitter disorders, molecular mechanisms and potential preventive intervention of radiation induced pubertal changes.

Risk of stillbirth in offspring of men exposed to ionising radiation

Radiation genetic risk models are employed to predict the frequency of radiation-related stillbirths to partners of occupationally exposed male workers, using the incidence data recently reported by Parker et al from an epidemiological study of Cumbrian births. Expanding on previously developed conservative risk estimates suggests that, of the 130 observed stillbirths to partners of male radiation workers, 0.3 cases would be attributable to paternal preconceptional irradiation, in contrast to the 17.5 (95% confidence interval: 3.1 to 31.9) cases predicted by Parker et al from their preferred dose-response model. The incompatibility of the results reported by Parker et al with those from other investigations, both epidemiological and experimental, and the inability of the study to consider a number of factors which might affect stillbirth rates, particularly those relating to the mother, make it difficult to accept that paternal irradiation received occupationally could have contributed to a detectable increase in stillbirths.

Cranial irradiation and central hypothyroidism

Cranial irradiation causes thyrotropin (TSH)-releasing hormone (TRH) secretory abnormalities. TRH deficiency leads to abnormal glycosylation of TSH alpha and beta subunits and loss of the normal circadian pattern of TSH secretion (low in the afternoon, a surge in the evening, higher at night). This disruption results in either mixed hypothyroidism (raised TSH with abnormal secretory kinetics) or central hypothyroidism (abnormal secretory kinetics without raised TSH). Although primary hypothyroidism is more common in the general population and cancer survivors, the cumulative incidence of central and mixed hypothyroidism is high during the ten years after cranial irradiation. Monitoring for decline in free thyroxine (FT(4)) and rise in serum TSH, and early recognition using TSH surge and TRH tests, are clinically valuable. Early thyroid hormone replacement therapy to achieve serum FT(4) in the upper half of the normal range is crucial for maintaining optimal health and growth in cancer survivors.

The effect of pulsed and sinusoidal magnetic fields on the morphology of developing chick embryos

Several investigators have reported robust, statistically significant results that indicate that weak (approximately 1 microT) magnetic fields (MFs) increase the rate of morphological abnormalities in chick embryos. However, other investigators have reported that weak MFs do not appear to affect embryo morphology at all. We present the results of experiments conducted over five years in five distinct campaigns spanning several months each. In four of the campaigns, exposure was to a pulsed magnetic field (PMF); and in the final campaign, exposure was to a 60 Hz sinusoidal magnetic field (MF). A total of over 2500 White Leghorn chick embryos were examined. When the results of the campaigns were analyzed separately, a range of responses was observed. Four campaigns (three PMF campaigns and one 60 Hz campaign) exhibited statistically significant increases (P > or = 0.01), ranging from 2-fold to 7-fold, in the abnormality rate in MF-exposed embryos. In the remaining PMF campaign, there was only a slight (roughly 50%), statistically insignificant (P = 0.2) increase in the abnormality rate due to MF exposure. When the morphological abnormality rate of all of the PMF-exposed embryos was compared to that of all of the corresponding control embryos, a statistically significant (P > or = .001) result was obtained, indicating that PMF exposure approximately doubled the abnormality rate. Like-wise, when the abnormality rate of the sinusoid-exposed embryos was compared to the corresponding control embryos, the abnormality rate was increased (approximately tripled). This robust result indicates that weak EMFs can induce morphological abnormalities in developing chick embryos. We have attempted to analyze some of the confounding factors that may have contributed to the lack of response in one of the campaigns. The genetic composition of the breeding stock was altered by the breeder before the start of the nonresponding campaign. We hypothesize that the genetic composition of the breeding stock determines the susceptibility of any given flock to EMF-induced abnormalities and therefore could represent a confounding factor in studies of EMF-induced bioeffects in chick embryos.

Enhancing effect of maternal zinc deficiency and 137Cs gamma-irradiation on the frequency of fetal malformations in mice

It is well established that in mammals transitory zinc (Zn) deficiency during embryogenesis can have a negative influence on fetal development. Similar to Zn deficiency, maternal exposure to low levels of ionizing radiation during the first day of pregnancy has been shown to negatively affect preimplantation embryo development, and higher doses of maternal irradiation during late stages of embryogenesis can result in malformations. Here we report the effect of transitory maternal Zn deprivation combined with low dose irradiation during embryogenesis on fetal outcome. Pregnant mice were acutely dosed with 0.00, 0.05, 0.10, or 0.25 Gy of gamma-radiation the day after mating (GD0), or with 0.00 or 0.50 Gy on GD8. Mice irradiated on GD0 were either fed a low Zn diet (0.4 microgram Zn/g) for 48 h prior to mating through GD0 or GD5 and then switched to a control diet (50 micrograms Zn/g) through GD18, or they were fed the control diet throughout gestation. Dams irradiated on GD8 were either fed the low Zn diet from GD0 through GD10 and then switched to the control diet, or they were fed the control diet throughout gestation. Zn deprivation did not influence any of the maternal or embryonic/fetal parameters measured in the cohorts fed the low Zn diet through GD0. In contrast, groups fed the low Zn diet through GD5 or GD10 had lower mean maternal body weights, fewer live fetuses/litter, and a higher incidence of resorptions than controls. Fetuses from dams fed the low Zn diet through GD10 were smaller and shorter, and had a higher frequency of malformations than controls. Irradiation on GD8 under adequate Zn conditions had no effect on any parameter, but GD8 irradiation during maternal Zn deficiency had an additive effect on the frequency of fetal malformations.

Applied DC magnetic fields cause alterations in the time of cell divisions and developmental abnormalities in early sea urchin embryos

Most work on magnetic field effects focuses on AC fields. The present study demonstrates that exposure to medium-strength (10 mT-0.1 T) static magnetic fields can alter the early embryonic development of two species of sea urchin embryos. Batches of fertilized eggs from two species of urchin were exposed to fields produced by permanent magnets. Samples of the continuous cultures were scored for the timing of the first two cell divisions, time of hatching, and incidence of exogastrulation. It was found that static fields delay the onset of mitosis in both species by an amount dependent on the exposure timing relative to fertilization. The exposure time that caused the maximum effect differed between the two species. Thirty millitesla fields, but not 15 mT fields, caused an eightfold increase in the incidence of exogastrulation in Lytechinus pictus, whereas neither of these fields produced exogastrulation in Strongylocentrotus purpuratus.

The AAPM/RSNA physics tutorial for residents. Typical patient radiation doses in diagnostic radiology

Factors affecting patient dose in all x-ray imaging modalities include beam energy, filtration, collimation, patient size, and image processing. In conventional radiography, the most important determinant of acceptable patient dose is use of the highest peak kilovoltage that results in diagnostic images. Digital radiography allows a much wider range of exposures than conventional radiography for producing diagnostic images. However, operators must be aware of the subtle differences in techniques used with digital systems to avoid unnecessary increases in patient dose. Low-dose mammography requires lower ranges of peak kilovoltage; different target materials, filters, and screen-film combinations; special attention to breast thickness, composition, and compression during the study; and different standards for grids, magnification, and optical density. Although peak kilovoltage and tube current are important for controlling patient dose in fluoroscopy, collimation, source-to-skin and patient-to-image intensifier distances, and control of beam-on time have perhaps greater importance. Computed tomography (CT) involves greater patient dose than conventional radiography, and, although the primary radiation dose is delivered to smaller volumes, dose calculations must account for dose received by adjacent tissue sections. Many variables are involved in fetal exposure and fetal dose effects, but a solid understanding of them can help in developing responsible patient management practices.

Adaptive response in embryogenesis: II. Retardation of postnatal development of prenatally irradiated mice

We previously reported that a priming dose of 0.3 Gy on gestation day 11 significantly increased the rate of living fetuses and reduced the incidence of congenital malformations caused by exposure to 5 Gy X rays on gestation day 12 in ICR mice. In the present study, postnatal development of the live offspring was investigated using a set of developmental and behavioral parameters. The offspring of the mice irradiated with 0.3 Gy generally showed a delay in the appearance of most of the physiological markers, impaired acquisition of neonatal reflexes, and alteration of adult behavior. However, an increase in body weight in the females was observed 4 weeks postnatally. In the offspring primed with 0.3 Gy followed by a challenging dose of 5 Gy prenatally, a high postnatal mortality was found, and all the survivors had various radiation-induced detrimental effects. The results indicated that the priming dose was advantageous to survival itself, but was disadvantageous to the health of survivor. The results also suggested that studying the whole animal can show the extent of the effects of radiation, i.e. quality of life, in a way that cellular or molecular studies cannot.

Fetal doses from radiological examinations

There has been growing concern about radiation exposures in the case of pregnant women who undergo radiological examinations of the lower abdomen and pelvis, when the embryo/fetus is near or included in the X-ray field. This paper describes a retrospective study of 50 pregnant women accrued over a period of 10 years. Most of these women were not aware of pregnancy at the time of their radiological examinations. They subsequently discovered that they were pregnant and sought advice from their physicians on fetal dose and risk. They were then referred to a Radiation Protection Advisor for an estimation of the fetal dose. Radiation absorbed dose to the embryo/fetus was estimated from a knowledge of technique factors and examination details using normalized uterine doses published by the National Radiological Protection Board (NRPB). Doses to the embryo/fetus varied between less than 0.01 microGy and 117 mGy, depending on the examination. Gestational ages ranged between 2 and 24 weeks.