Nuclear radiation and prevalence of structural birth defects among infants born to women from the Marshall Islands.

BACKGROUND: With their unique history of exposure to extensive nuclear testing between 1946 and 1958, descendants of Marshall Island residents may have underappreciated genetic abnormalities, increasing their risk of birth defects. METHODS: We conducted a retrospective cohort study of resident women with at least one singleton live birth between 1997 and 2013 in northwest Arkansas using state birth certificate data linked to data from the Arkansas Reproductive Health Monitoring System, a statewide birth defects registry. We calculated unadjusted and adjusted prevalence ratios (PR) and 95% confidence intervals (CI) from modified Poisson regression analyses for non-Hispanic (NH) whites, NH-blacks, Hispanics and Marshallese, using NH-whites as the reference group. RESULTS: Of the 91,662 singleton births during the study period, 2,488 were to Marshallese women. Due to the relatively small number of Marshallese births, we could not calculate prevalence estimates for some defects. Marshallese infants had higher rates of congenital cataracts (PR = 9.3; 95% CI: 3.1, 27.9). Although the number of defects was low, Marshallese infants also had higher rates of truncus arteriosus (PR = 44.0; 95% CI: 2.2, 896.1). CONCLUSIONS: Marshallese infants may have increased risk of specific birth defects, but estimates are unstable because of small sample size so results are inconclusive. Larger population-based studies would allow for further investigation of this potential risk among Marshallese infants.

Biomolecular changes and somatic mutations induced by UV laser irradiation at embryonic stage of Bombyx mori.

PURPOSE: To determine the impact of ultraviolet (UV) laser radiation on Bombyx mori embryos in terms of its effect on embryonic and larval haemolymph proteins and morphological traits. MATERIALS AND METHODS: The eggs of silkworm strain NB4D2 were exposed to third harmonic laser pulses at 355 nm from a Nd:YAG laser for different durations of 30, 60, 90, 120, 150, or 180 sec. Morphological changes induced by the UV laser were analysed at larval, pupal and adult stages. The eggs exposed to UV laser irradiation at different developmental stages were subjected to protein analysis by sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE). The haemolymph derived from irradiated and control larva was also analysed by SDS-PAGE. RESULTS: UV laser irradiation resulted in various structural polymorphisms. Asymmetrical fusion of segments was not confined to larva but persisted throughout pupal and adult stages. Development of extra caudal horn, unequal size and lack of antenna, retarded thoracic legs and variation in larval markings were observed. Comparatively, the effect of the UV laser on 8- and 16-h old embryo was greater than on the other stages. The changes in protein pattern were not distinct until the 5th day of embryogenesis as revealed by SDS-PAGE. A 178 kiloDalton (kDa) protein resolved into 198, 184 & 169 kDa polypeptides and 154 kDa new protein band along with other proteins of 110, 45, 41 & 38 kDa were noticed in irradiated eggs at the 6th day. Further, 33, 32, and 6.2 kDa new protein bands were observed in the haemolymph of 5th instar silkworm larvae derived from UV laser irradiated embryos. CONCLUSIONS: A comparative analysis of the present study revealed that UV laser not only induced continuous structural polymorphisms (somatic mutations), but also induced protein changes with the appearance of new protein bands in embryonic and haemolymph protein. The UV laser could be a potential tool for biochemical genetics and genome analysis in B. mori.

Atm-null mice exhibit enhanced radiation-induced birth defects and a hybrid form of embryonic programmed cell death indicating a teratological suppressor function for ATM.

ATM (ataxia-telangiectasia mutated) is a genotoxic stress transducer. In this first report of Atm-dependent birth defects, Atm-null embryos were uniquely susceptible to low-dose (0.5 Gy) radiation, exhibiting severe runting, tail anomalies, and lethality, independent of cell cycle arrest or insulin-like growth factor 1. This treatment enhanced levels of p53 protein and central nervous system (CNS) apoptosis in wild-type mice, but not Atm-null mutants, at 6 h postirradiation. At 48 h, however, this pattern was reversed, with Atm-null mice exhibiting high levels of a hybrid form of programmed cell death within the CNS. Even heterozygous Atm-deficient embryos were radiosensitive to a higher radiation dose of 2 Gy. These results show that Atm is a novel teratologic suppressor gene protecting embryos from pathological cell death and teratogenesis initiated by even mild DNA damage.

Malformations after radiation exposure of preimplantation stages.

Our studies have shown that, contrary to the opinion in most textbooks, it is possible to increase the number of malformed fetuses in one of our mouse strains (originally "Heiligenberger Stamm", meanwhile HLG/Zte) by radiation exposure of zygotes or of subsequent preimplantation stages. The malformation affected most pronouncedly is gastroschisis, a defect occurring at a frequency of 1 to 4% in the controls. The observed increase is strain specific (C57Bl mice or (HLGxC57Bl)F1 hybrids do not react in the same way), it is accompanied by an increased frequency of chromosomal aberrations in skin fibroblasts and of modified protein patterns in liver, kidney, and skin cells of day 19 fetuses. The most probable explanation seems to be the assumption that radiation exposure of preimplantation stages increases a defect with a genetic predisposition in a specific way and labelizes the genome of subsequent cell generations making these cells more susceptible for noxes acting on the fetus.

Embryonic death, dwarfism and fetal malformations after irradiation of embryos at the zygote stage: studies on two mouse strains.

Female mice of the BALB/c and CF1 strains were mated and irradiated with various doses of X-rays 7 h after presumed fertilization. 18 days later, females were killed and their uteri examined for prenatal mortality at the different stages of development. Living fetuses were weighed and examined for the presence of external malformations. A number of them were also examined for skeletal anomalies. Radiation induced mainly a dose-dependent increase of the preimplantation loss in the BALB/c strain and of the early postimplantation loss in the CF1 strain. Embryos of the BALB/c strain were refractory to the induction of teratogenic effects after such preimplantation irradiation. In CF1 mice, the frequency of malformed fetuses increased regularly after irradiation, the difference with controls being significant for the doses of 10, 50 and 100 cGy. Dwarfism occurrence also appeared to be increased by irradiation in this strain, although the importance of this effect varied depending on the criterion chosen for the assessment of dwarfs. With the definition proposed in the present paper, the increase in the frequency of dwarfs paralleled that of malformed fetuses, being significant after doses of 50 and 100 cGy. Irradiation did not increase the frequency of skeletal anomalies. A careful examination of the various data obtained to data led us to conclude that radiation may possibly be teratogenic in several mouse strains, when administered as early as during the one-cell stage and, to a lesser extent, during the following preimplantation stages. However, early prenatal mortality will remain by far the greatest risk associated with an exposure to radiation during this period. Moreover, the relativity of the risk of abnormality due to such irradiation should be considered in the context of the high prevalence of developmental defects spontaneously occurring during human pregnancy.

Dependence of malformation upon gestational age and exposed dose of gamma radiation.

In order to evaluate the importance of gestational age and the dose-incidence relationship by gamma radiation, pregnant ICR mice at gestational days from 2.5 to 15.5 days post-coitus (p.c.) were exposed to a single dose of 2.0 Gy and also at day 11.5 after conception, which was the most sensitive stage for the induction of major congenital malformations. The animals were sacrificed on day 18 of gestation and the fetuses were examined for mortality, growth retardation, changes in head size and other morphological abnormalities. The only demonstrable effect of irradiation during the pre-implantation period was an increase in prenatal mortality. Resorptions were maximal on exposure at day 2.5 after conception. The pre-implantation irradiated embryos which survived did not show any major fetal abnormalities. A small head, growth retardation, a cleft palate, dilatation of the cerebral ventricle, a renal pelvis, and abnormalities of the extremities and tail after exposure were prominent during the organogenesis period, especially on day 11.5 of gestation. As for the dose-incidence relationship, the incidence of a small head, growth-retarded fetuses, a cleft palate, dilatation of cerebral ventricle and abnormalities of the extremities in live fetuses rose as the radiation dose increased. The result indicated that the late period of organogenesis in the development of the brain, skull and extremities of a mouse was a particularly sensitive phase. The threshold doses of radiation that induced a cleft palate and dilatation of the cerebral ventricle, and abnormal extremities were between 1.0 and 2.0 Gy, and between 0.5 and 1.0 Gy, respectively.

Syndromology: an updated conceptual overview. VII. Aspects of teratogenesis.

Principles of teratogenesis are reviewed, including adverse environmental factors and the genotype, timing of exposure, mechanisms and pathogenesis, the nature of teratogenic agents, manifestations of deviant development, and dosage. Human teratogenic conditions are summarized with special emphasis on the fetal alcohol syndrome, fetal hydantoin syndrome, fetal trimethadione syndrome, fetal valproate syndrome, warfarin embryopathy, retinoic acid embryopathy, congenital rubella syndrome, radiation effects, and diabetic embryopathy.

[Contribution and limitations of experimental models to the understanding of certain abnormalities of the face and ear]. / Apports et limites des modèles expérimentaux à la compréhension de certaines malformations de la face et de l'oreille.

The analysis of 4 craniofacial teratological models in the mouse (13-cis-retinoic acid and methyl triazene administration, irradiation, 'far' strain) permits to study the similarities, but also the differences between these models and malformative syndromes in the human. Retinoic acid administration provides a phenocopy of mandibulofacial dysostosis, and irradiation gives rise to a centrofacial dysplasia evoking several holoprosencephalia and Crouzon syndrome. However, triazene administration does not reproduce the hemicraniofacial microsomia.

[The radiation effects of low doses of irradiation on human embryos and fetuses]. / Radiatsionnye éffekty malykh doz oblucheniia na émbriony i plody cheloveka.

Data about the biological effect of irradiation at "small" doses on prenatal development of man are reviewed. The effect of irradiation is observed either immediately after it or in progeny, as consequences of radiation damage to the embryo or fetus. Human embryos and fetuses are most sensitive to ionizing irradiation during the periods of the maximal proliferative activity and differentiation of cells. The concept is formulated that any dose of irradiation, however small, can inflict damage to the embryo or fetus. Problems and perspectives for studies in this field are discussed.

[The morphogenesis of the retinal neural layer and of the optic nerve in the normal white rat and under the action of large doses of x-ray irradiation during prenatal ontogeny]. / Morfogenez nervnogo sloia setchatki glaza i zritel'nogo nerva beloi krysy v norme i pri deistvii bol'shikh doz rentgenovskogo oblucheniia v period prenatal'nogo ontogeneza.

Development of retina nerve layer and optic nerve were studied in 50 embryos and fetuses of albino rat in normal embryogenesis and in 55 embryos affected by large doses of X-ray irradiation (2.24 Cy) on d 10-14 of pregnancy (second critical period-a period of placentation and organogenesis). Main regularities in the development of the structures studied were demonstrated in intact fetuses. In the experiment the progeny subjected to X-ray irradiation showed basically bilateral abnormalities in development of retina nerve layer, optic nerve and its coats.

Transgenerational transmission of radiation damage: genomic instability and congenital malformation.

The congenital malformation gastroschisis has a genetic disposition in the inbred mouse strain HLG/Zte. It is increased after preconceptional irradiation of males or females. Radiation exposures during the meiotic stages are most efficient. This malformation can also be induced by ionising radiation when the exposure takes place during the preimplantation period especially during the zygote stage. This latter effect can be transmitted to the next mouse generation. Other macroscopically visible or skeletal malformations are not significantly induced under these experimental conditions. These latter malformations are increased by radiation exposures during major organogenesis. The mechanisms for the development of the effects are different. Radiation exposure of the mouse zygote (1 to 3 hours p.c.) also leads to the induction of genomic instability in skin fibroblasts of the fetus. This phenomenon also occurs in a mouse strain (C57BL/6J) which is not susceptible to radiation-induced gastroschisis during the preimplantation period. The genomic instability is transmitted to the next mouse generation. During genomic instability chromatide breaks are dominating as in non-exposed cells. With respect to "spontaneous" malformations gastroschisis is dominating in HLG/Zte mice. Late radiation effects seem to have similar patterns as observed in non-exposed subjects, however, the rates are increased after irradiation.

Correlation of Hsp110 expression with caspase-3 and -9 during apoptosis induced by in vivo embryonic exposition to retinoic acid or irradiation in early mouse craniofacial development.

OBJECTIVE: To analyze the expression and role of three proteins (HSP110, caspase-3 and caspase-9) during craniofacial development. DESIGN: Seven pregnant C57Bl/6J mice received, by force-feeding at gestation day 9 (E9), 80 mg/kg of all-trans retinoic acid mixed to sesame oil. Seven pregnant NMRI mice received two grays irradiation at the same gestation day. Control mice of both strains (seven mice for each strain) were not submitted to any treatment. Embryos were obtained at various stages after exposition (3, 6, 12 and 24 h), fixed, dehydrated and embedded. Coronal sections (5 microm) were made. Slide staining occurred alternatively using anti-Hsp110, anti-caspase-3 and anti-caspase-9 immunohistochemistry. RESULTS: Expression of HSP110, caspase-3 and caspase-9 was found in cells of well-known locations of programmed cell death. After retinoic acid exposure, expressions were increased especially in neural crest cells of mandibular and hyoid arches. Quantification of positive cells shows that caspase-9 and Hsp110 were expressed before caspase-3. After irradiation, the expression of the three proteins quickly increased with a maximum 3 h after irradiation. For all three models of apoptosis (physiological, retinoic-induced and irradiation-induced) HSP110 positive cells were more numerous than caspase-3 positive cells. Caspase-3 positive cells were more numerous than caspase-9 positive cells especially in mesectodermal irradiation-induced apoptotic cells. CONCLUSION: The findings show a potential function of HSP110 in apoptosis during embryo development. Caspase-3-expressing cells are more numerous than cells expressing caspase-9, especially irradiation-induced apoptotic neural crest cells. This suggests that other caspases, still to be identified, may activate caspase-3 in this model.

Lethal and teratogenic effects of long-term low-intensity radio frequency radiation at 428 MHz on developing chick embryo.

Exposure of developing chick embryos to 428 MHz radio frequency (RF) radiation at a power density of 5.5 mW/cm2 for more than 20 days resulted in embryolethal and/or teratogenic effects and delayed hatching. These adverse biological effects were not due to any thermal effect of the RF radiation. We have demonstrated teratogenicity in the chick embryo as a result of protracted low-dose RF irradiation.

Lethal and teratogenic effects after exposure to X-rays at various times of early murine gestation.

Various well-defined stages during completion of the second meiotic division and early organogenesis of mouse embryos were X-irradiated with doses of 1-4 Gy (100-400 rad). The major risk was prenatal mortality with radiation sensitivity changing markedly with dependence on the developmental stage irradiated; in the case of day 1 even within hours. The surviving fetuses did show a significantly enhanced frequency of malformations on day 19 of gestation (mostly gastroschisis and some exencephalies). This was true for all stages between days 1 and 8; only sensitivity again changed considerably. The radiation doses used in this study are markedly higher than doses that can be expected from radiation diagnostics, but exposure is in a range comparable to doses that can occur in radiation therapy (e.g., Morbus Hodgkin).

Lens formation in the absence of optic cup in rat embryos irradiated with soft X-ray.

In order to investigate the effect of soft X-ray irradiation on ocular development, pregnant rats were exposed to a single 12.5 Gy irradiation on embryonic day 9 (ED 9). The embryos obtained by laparotomy on ED 12 and 21 were examined for ocular abnormalities under a binocular stereo-microscope and a light microscope. The ED 12 embryos were stained with osmium tetroxide to facilitate the observation. The stereo-microscopic examination on ED 12 and 21 revealed various types of ocular abnormalities characterized primarily by aplasia or hypoplasia of the optic cup and invaginated lens placode. The light microscopic examination further confirmed these findings histomorphologically, and the hypoplastic abnormalities were classified into three types: (1) hypoplasia of the optic cup and invaginated lens placode, (2) complete malformation of the optic cup and hypoplasia of the invaginated lens placode, and (3) complete malformation of the optic cup and invaginated lens placode. Because the lens was formed in the complete absence of the retina, the development and differentiation of the retina and lens do not seem to be tightly synchronized. Thus, this sequential analysis on ocular abnormalities during the early stage of development supports the notion that the presence of the retina is not always necessary for the development of the lens.

[Pathogenesis of radiation-induced abnormalities of the bones and joints of white rat embryos]. / Patogenez luchevykh anomalii skeleta i sustavov zarodyshei beloi krysy.

After X-radiation of pregnant rats on the 10th day of pregnancy, in 50% of the fetuses studied subtotal aplasia of the tibial bone anlage and decreasing number of the metatarsus and finger phalanges anlages are observed. Radiation on the 11th day of embryogenesis does not result in anomaly formation of the thoracic and pelvic extremities. After radiation on the 12th day of embryogenesis, the most specific anomaly of the pelvic extremity is phocomelia. The thoracic extremity skeleton lesions are revealed as an ulnar type of distal ectromelia, or axial ectromelia. After radiation on the 13th--14th day, hypoplasia of the bone anlages, that make zeugopodium, autopodium, is observed. After radiation on the 13th day, a partial or total aplasia of the fibular bone anlage can take place. In all the fetuses a sharp decrease in number of the hand and foot bone anlages is observed; it is connected with a total aplasia of some of them and with fusion of the others. A specific feature for radiation lesions of the extremity skeleton is that the oppositely situated anlages of the bones do not separate from each other. This results from certain disturbances in the joint interzone formation at early stages of embryogenesis and from underdevelopment of the joint cleft. Qualitatively different radiation anomalies of the extremity skeleton development are formed as consequence of disturbances in morphogenetic processes of determination: migration, proliferation, morphogenetic cell death and differentiation.

[The development and structure of the optic nerve in normal embryos and fetuses of the white rat and after x-ray irradiation]. / Razvitie i stroenie zritel'nogo nerva u zarodyshei i plodov belo i krysy v norme i posle rentgenovskogo oblucheniia.

With the aim to reveal the ionising radiation effect to formation and structure of the optic nerve (ON), 55 white rat intact embryos and fetuses and 77 experimental embryos and fetuses, subjected to x-ray irradiation on the 10th-14th day of development, have been studied. The main regularities in formation of the ON have been stated under normal conditions. Certain disturbances in formation of the ON and in the internal membrane of the optic vesicle (future retina) under effect of x-rays in the dose of 2.24 Gy have been detected during the intrauterine period of development--folds, rosellas of retina, retardation in differentiation of the retina nervous layer, aberration of the ON growth with a subsequent reduction, the ON hypo- and aplasia, retardation in formation of neural sheaths, absence of intraspace between the sheaths.

Diagnostic nuclear medicine and risk for the fetus.

The possible detrimental effects on the developing embryo subsequent to irradiation are discussed. The doses to the embryo or fetus encountered for the most common procedures in diagnostic nuclear medicine are evaluated with respect to the threshold doses and the risks per cGy. The threshold dose for fatal and non-fatal malformations or other defects is, at the lowest estimate, 5-10 cGy. The dose which the embryo or fetus receives from diagnostic nuclear medicine is below 1 cGy. For the induction of fatal cancer and for genetic defects no threshold dose is assumed. The risk for the induction of cancer is 0.03%-0.05% per cGy. The risk for the induction of genetic defects is even lower (0.024%-0.099% per cGy). It is concluded that for common diagnostic nuclear medicine procedures the risk of detrimental effects on the embryo or fetus due to radiation is negligible. On the basis of present knowledge there are no radiation safety indications for abortus provocatus as a consequence of a diagnostic nuclear medicine study.

Effects and consequences of prenatal irradiation.

After a brief introduction about the historic development of risk estimates and maximum permissible doses of ionizing radiation, the risks of prenatal irradiation are discussed. Experimental data mainly obtained with mice indicate that the most important risk exists during the period of organogenesis and concerns the induction of malformations. Although in man this period lies between about 10 and 80 days after fertilization for most organs, the main development of the brain occurs later, namely between the 8th and 15th week after conception. Data from Japanese victims of the atomic bomb explosions above Hiroshima and Nagasaki indicate that during development the brain is the most sensitive organ to irradiation and maximal sensitivity is found between the 8th and 15th week after fertilization. A dose of one Gray received during this period induces a severe mental retardation in about 45% of the newborns. The dose response relationship is not significantly different from a linear one without a threshold dose. Studies of intelligence and school performance have shown that 1 Gray received during the 8th-15th week causes a shift of the average intelligence of about 30 points. Irradiation before the 8th week and after the 25th week had no effect on intelligence or mental retardation. During the 16th and 25th week sensitivity was about one fourth of that during the 8th-15th week. Although the irradiation of the embryo and fetus should be avoided as much as possible, the new data have led to an abandonment of the so-called 10-day rule. Generally an accidental irradiation of the embryo or fetus of less than 5 cGy is not considered as a medical indication for abortion. Retrospective studies showed that mothers from children who died from leukemia or other childhood tumors, had been subjected to a diagnostic irradiation of the pelvis or lower abdomen more frequently than mothers from children that did not develop a tumor. It has been estimated that prenatal sensitivity for induction of leukemia and tumors is higher than sensitivity after birth. However, it is still in discussion, whether the relationship between prenatal irradiation and a higher incidence of tumors is of a causal nature.