Estimates of microcurie-days residence,bone dose equivalent,and (MPC)W for thorium-232 in man using a mammillary model

A four-compartment mammillary model for the distribution and excretion of thorium and its daughter radium is studied and applied to the problem of estimating the radiation dose to organs and tissues of man for the case of a single intake of²³²Th. The long-lived daughter²²⁸Ra (∼6 y) grows in with time and gives birth to the other short-lived daughters (<0.4 day) which irradiate those tissues in the vicinity of their point of production. Some data on²²⁸Th and its daughter²²⁴Ra are available on dogs from which a model is derived and tested. Then, from some single-intake data (Th and Ra) on man, parameters for the model are estimated and estimates of residence times of the²³²Th daughters in man are made. Also, the 50-year radiation dose (dose equivalent) to bone from a single intake of²³²Th is estimated. Research sponsored by the U.S. Atomic Energy Commission under contract with Union Carbide Corporation.     

Molecular basis of α-thalassemia in Sicily

To evaluate the allelic frequency and genetic diversity of α-thalassemia defects in Sicily, both epidemiological and patient-oriented studies were carried out. For the epidemiological study, phenotypic data were collected on more than 1000 Sicilian individuals. Among them, 427 were explored at the molecular level for nine α-thalassemic variants known to be common in the Mediterranean region. Our data reveal an allele frequency of 4.1% for α⁺-thalassemia matching that of β-thalassemia in this region. The presence of α°-thalassemia (––^MEDI and ––^CAL) was observed only in the group of referred patients. Newly acquired nucleotide sequence data on the deletional breakpoint of ––^CAL allowed us to design a simple PCR-based procedure for exploring this allele. The data also provide additional information concerning the genetic mechanisms involved in such large deletions. Received: 8 August 1996 / Revised: 16 October 1996     

Transfer of radionuclides to ants, mosses and lichens in semi-natural ecosystems

There is a scarcity of data on transfer of both natural and anthropogenic radionuclides to detritivorous invertebrates for use in the assessment of radiation exposure. Although mosses and lichens have been extensively used in biomonitoring programs, the data on transfer of radionuclides to these species are limited, particularly for natural radionuclides. To enhance the available data, activity concentrations of ¹³⁷Cs, ²²⁶Ra and ²²⁸Ra were measured in ants, mosses and lichens and corresponding undisturbed soil collected from semi-natural ecosystems in Serbia and Montenegro and biota/soil concentration ratios (CR) calculated. Since the majority of internal dose to biota is expected to come from ⁴⁰K, the activity concentrations of this radionuclide were also determined. The mean CR values for ¹³⁷Cs, ²²⁶Ra and ²²⁸Ra in ants analyzed in this study were found to be 0.02, 0.06 and 0.02, respectively. The mean CR values of radionuclides in mosses were found to be 2.84 for ¹³⁷Cs, 0.19 for ²²⁶Ra and 0.16 for ²²⁸Ra, while those in lichens were found to be 1.08 for ¹³⁷Cs, 0.15 for ²²⁶Ra and 0.13 for ²²⁸Ra. The CR values obtained in this study were compared with default CR values used in the ERICA Tool database and also with those reported in other studies.     

Activity concentrations of <Superscript>226</Superscript>Ra, <Superscript>228</Superscript>Th,and <Superscript>40</Superscript>K in different food crops from a high background radiation area in Bitsichi,Jos Plateau,Nigeria

One of the three goals of the United Nations for sustainable food security is to ensure that all people have access to sufficient, nutritionally adequate, and safe food. Decades of tin mining in the Bitsichi area of the Jos Plateau, Nigeria, have left a legacy of polluted water supplies, impoverished agricultural land, and soil containing abnormally high levels of naturally occurring radioactive elements. In order to ascertain the radiological food safety of the population, different crops that constitute the major food nutritive requirements were collected directly across farmlands in the area. The activity concentrations of ²²⁶Ra, ²²⁸Th, and ⁴⁰K were determined in the food and soil samples using γ-ray spectrometry. Additionally, in situ gamma dose rate measurements were performed on the farms using a pre-calibrated survey meter. The corresponding activity concentrations in the food crops ranged from below detection limit (BDL) to 684.5 Bq kg⁻¹ for ⁴⁰K, from BDL to 83.5 Bq kg⁻¹ for ²²⁶Ra, and from BDL to 89.8 Bq kg⁻¹ for ²²⁸Th. Activity concentrations of these radionuclides were found to be lower in cereals than in tubers and vegetables. As for the soil samples, activity concentrations of these radionuclides varied from BDL to 166.4 Bq kg⁻¹, from 10.9 to 470.6 Bq kg⁻¹, and from 122.7 to 2,189.5 Bq kg⁻¹ for ⁴⁰K, ²²⁶Ra, and ²²⁸Th, respectively. Average external gamma dose rates were found to vary across the farms from 0.50 ± 0.01 to 1.47 ± 0.04 μSv h⁻¹. Due to past mining activities, the soil radioactivity in the area has been modified and the concentration level of the investigated natural radionuclides in the food crops has also been enhanced. However, the values obtained suggest that the dose from intake of these radionuclides by the food crops is low and that harmful health effects are not expected.     

Long-term development of the radionuclide exposure of murine rodent populations in Belarus after the Chernobyl accident

As a determinant of the associated health risks, the behavior of radionuclides in natural ecosystems needs to be better understood. Therefore, the activity concentration of various long-lived radionuclides released due to the Chernobyl accident, and the corresponding contributions to the whole-body dose rate, was studied as a function of time in mammalian indicator species inhabiting the natural forest ecosystems of Belarus, the bank vole (Clethrionomys glareolus) and the yellow-necked mouse (Apodemus flavicollus). The activity concentrations of ¹³⁷Cs, ¹³⁴Cs, ⁹⁰Sr, ²³⁸Pu, ^239,240Pu, ²⁴¹Pu and ²⁴¹Am in soil and in animals were measured at five monitoring sites with different ground deposition of radionuclides at different distances from the destroyed reactor. The observed temporal pattern of the radionuclide activity concentration in the studied animal populations reflects the changes in biological availability of these isotopes for biota, mostly due to fuel particle destruction and appearance of dissolved and exchangeable forms of radionuclides. The time course of ^134+137Cs activity concentrations in animal populations appeared as a sequence of increase, peak and decrease. Maximal levels of radiocesium occurred 1–2 years after deposition, followed by an exponential decrease. Concentrations of incorporated ⁹⁰Sr increased up to the tenth year after deposition. The activity concentrations of transuranic elements (²³⁸Pu, ^239,240Pu, ²⁴¹Pu and ²⁴¹Am) were much lower than those of the other radionuclides, in the studied animals. A considerable activity of ²⁴¹Am in animals from areas with high levels of contamination was firstly detected 5 years after deposition, it increased up to the tenth year and is expected to increase further in the future. Maximal values of the whole-body absorbed dose rates occurred during the year of deposition, followed by a decrease in the subsequent period. Generally, this decrease was monotonic, mainly determined by the decrease of the external γ-ray dose rate, but there were exceptions due to the delayed maximum of internal exposure. The inter-individual distributions of radionuclide concentrations and lifetime whole-body absorbed doses were asymmetric and close to log-normal, including concentrations and doses considerably higher than the population mean values.     

Projection of cancer risks from the Japanese atomic bomb survivors to the England and Wales population taking into account uncertainty in risk parameters

Generalized relative risk models, with adjustments to the relative risk for time after exposure and age at exposure and incorporating a linear-quadratic dose response, were fitted to the latest (Life Span Study Report 12) Japanese atomic bomb survivor cancer mortality data using Bayesian Markov Chain Monte Carlo methods, taking account of random errors in the DS86 dose estimates. The resulting uncertainty distributions in the relative risk model parameters were used to derive uncertainties in population cancer risks for a current UK population. Following an assumed administered dose of 1 Sv, leukaemia mortality risks were estimated to be 1.93×10^–2 Sv^–1 (95% CI 1.14, 3.38), or 0.44 years of life lost Sv^–1 (95% CI 0.22, 0.94). Following an assumed administered dose of 1 Sv, solid cancer mortality risks were calculated to be 10.36×10^–2 Sv^–1 (95% CI 8.41, 12.42), or 1.38 years of life lost Sv^–1 (95% CI 1.11, 1.68). In general, solid cancer risks were very similar to those predicted by classical likelihood-based methods; however, leukaemia risks were somewhat higher, by 10–35%, than those predicted by classical likelihood-based methods. This is so in both cases, irrespective of whether or not adjustments are made in these likelihood-based fits for the effects of measurement errors, and the discrepancy for leukaemia tends to be greater at higher doses. Overall, cancer risks predicted by Bayesian Markov Chain Monte Carlo methods are similar to those derived by classical likelihood-based methods and which form the basis of established estimates of radiation-induced cancer risk. Received: 28 September 1999 / Accepted: 21 August 2000     

Measurement of resuspended aerosol in the Chernobyl area

During anthropogenic activities, such as agricultural soil management and traffic on unpaved roads, size distribution measurements were performed of atmospheric particulate radionuclides at a site in the Chernobyl 30-km exclusion zone. Analysis of cascade impactor measurements showed an increase of the total atmospheric radioactivity. In the cases of harrowing by a tractor and traffic on unpaved roads, a common shape of the size distribution was found with two maxima, the first in the 2–4 μm range, the second in the 12–20 μm range. The size distributions were compared to measurements during wind-driven resuspension. Particle number concentration measurements with an Aerodynamic Particle Sizer showed a dynamic dependence of the particle concentration in different size ranges on anthropogenic action. The increase of the mean concentration was for the large particles more than one order of magnitude higher than for fine particles during anthropogenic enhanced resuspension. From the measurement of the mass concentration, the radioactive loading could be estimated. An enrichment of radionuclides on resuspended particles (compared to soil particles) was found, with the highest enrichment for large particles. Micrometeorological considerations showed that large particles may frequently be subject to medium range transport. The dry deposition velocity was measured; the mean value of 0.026 m s^–1±0.016 m s^–1 is typical for 6–9 μm diameter particles. Received: 17 February 1998 / Accepted in revised form: 17 June 1998     

Peteosthor - a medical disaster due to Radium-224A personal recollection

Up to the end of World War II, there was no effective therapy against bone tuberculosis, and even today there is no treatment for ankylosing spondylitis. However, in the 1940s up to about 1956, radiotherapy with "Peteosthor" - a drug containing Thorium X ((224)Ra) as an effective compound - was introduced in Germany as a presumed cure and it maintained a central place in the treatment of these diseases. In 1948, I was entrusted to assess the new treatment. Animal studies and the clinical evaluation of the patients made me soon realise a number of severe adverse health effects which induced me to pronounce and subsequently repeat warnings against the intravenous administration of high doses of (224)Ra, especially because it was then administered predominantly to children and juveniles. As a consequence, this type of treatment was finally abandoned in 1956. But there remained a need to observe and document the resulting late health effects. Already in 1967, our initial follow-up study provided data for about 800 patients with exact information on the (224)Ra dose levels administered, administration schemes, and the resulting detrimental effects. A large number of bone sarcomas was the most severe consequence, but even today there is a broad spectrum of other grave health effects. A summary of the major scientific insights which have been achieved in the course of the still on-going epidemiological studies is part of this report.     

Benzodiazepines in the brain

Great progress has been made in the last 5 yr in demonstrating the presence of benzodiazepines (BDZs) in mammalian tissues, in beginning studies on the origin of these natural compounds, and in elucidating their possible biological roles. Many unanswered questions remain regarding the sources and biosynthetic pathways responsible for the presence of BDZs in brain and their different physiological and/or biochemical actions. This essay will focus on recent findings supporting that: (1) BDZs are of natural origin; (2) mammalian brain contains BDZs in concentrations ranging between 5.10⁻¹⁰–10⁻⁸ M; (3) dietary source of BDZs might be a plausible explanation for their occurrence in animal tissues, including man; (4) the formation of BDZ-like molecules in brain is a possibility, experimentally supported; (5) BDZ-like molecules including diazepam andN-desmethyldiazepam are elevated in hepatic encephalopathy; and (6) natural BDZs in the brain are involved in the modulation of memory processes. Future studies using the full range of biochemical, physiological, behavioral, and molecular biological techniques available to the neuroscientist will hopefully continue to yield exciting and new information concerning the biological roles that BDZs might play in the normal and pathological functioning of the brain.     

Comparative study of desert truffles from kuwait and other countries in the middle east for radionuclide concentration

Concentrations of some radionuclides, including¹³⁷Cs, in desert truffles in Kuwait were studied and compared with similar samples from other countries in the Middle East, namely Iran, Egypt, and Tunisia. In addition, sand samples from Kuwait were assayed to calculate the transfer factor of the radionuclides under consideration. The measured concentrations of⁴⁰K,²²⁶Ra, and¹³⁷Cs show that¹³⁷Cs is much higher in Egyptian samples, whereas⁴⁰K is much lower in samples from Tunisia. The average effective dose equivalent calculated for the Kuwaiti population according to their diet habits was found to be in the range 0.14-0.23 ΜS_v/a. The results are compared with values from other countries.     

Using the RESRAD Code to Assess Human Exposure Risk to 226Ra, 232Th,and 40K in Soil

This article evaluates the health risk raised by exposure to naturally occurring radionuclides in soil around Khak-Sefid, Ramsar, Iran, which is an area of high natural background radiation. A high purity germanium detector was used to determine levels of radionuclides in soil samples and the cancer morbidity risk for a hypothetical resident farmer was evaluated using the RESidual RADioactivity (RESRAD) code. The average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be 13,201 ± 391, 27.9 ± 2.4, and 415.5 ± 16 Bq/kg, respectively. The maximum assessed cancer morbidity risks were calculated from external and internal exposure pathways as 4.73 × 10^?2 and 3.40 × 10^?2 for ²²⁶Ra, 1.41 × 10^?4 and 7.88 × 10^?5 for ²³²Th, and 1.3 × 10^?4 and 4.233 × 10^?4 for ⁴⁰K. The RESRAD calculations also showed total cancer morbidity risks from external gamma and plant ingestion pathways were more important than from other exposure pathways. A sensitivity analysis was also performed to determine the input parameter values in the risk assessment process. In general, due to the high calculated risk of ²²⁶Ra compared with ²³²Th and ⁴⁰K it can be the major source of concern for human heath in the study area.     

Scanning the fossil record: stratophenomics and the generation of primary evolutionary-ecological data

The amount and quality of paleontological data is rapidly increasing thanks to the new developments in geological dating, 3D visualization and morphometrics, chemical and histological analysis, and database storage. However, despite the fact that data from fossils, their assemblages, temporal successions, spatial gradients and environments are of an evolutionary-ecological nature, their contribution to current mainstream evolutionary-ecological theory and methodology is low. The use of fossils is not seldom restricted to calibration (e.g., in phylogenetics), or source for historical speculation after having analyzed modern data first (e.g., in macroecology). Yet, the scale of resolution of many paleontological time series (10³–10⁵ years) is highly apt for studying the dynamics of species, the average lifetime of which is in the order of 10⁶–10⁷ years. In order to fully profit from the wealth of data from the rock archive, a large-scale “stratophenomics” approach is needed. The resulting data archives will not only further contribute to an increase in the knowledge of past species, communities and environments, but will also generate more and innovative theory on the mechanisms underlying species and higher taxon dynamics. Examples of new and promising approaches towards generating paleontological data will be presented under the headings of the three major stratophenomics dimensions: time, morphology and environment. Highlighted fields include astrochronology, sclerochronology and 3D morphometrics.     

��13C signature of tree rings and radial increment of Fagus sylvatica trees as dependent on tree neighborhood and climate

We conducted dendroecological analyses in 80-year-long tree ring chronologies to detect neighborhood effects (competition intensity, species identity) on the δ¹³C signature of tree rings and radial stem increment of Fagus sylvatica trees growing either in monospecific or mixed patches of a temperate forest. We hypothesized that tree ring δ¹³C is a more sensitive indicator of neighborhood effects and the impact of climate variability on growth than is ring width. We found a closer correlation of summer precipitation to δ¹³C than to ring width. While the ring width showed a decline over the test period (1926–2005), the mean curve of δ¹³C increased until the mid of the 1970s, remained high until about 1990, and markedly decreased thereafter. Possible explanations related to ontogeny and environmental change (‘age effect’ due to canopy closure; elevated atmospheric SO₂ concentrations in the 1960s–1980s) are discussed. Beech target trees surrounded by many allospecific trees had a significantly lower mean δ¹³C in the period 1926–1975 than beech with predominantly or exclusively conspecific neighborhood, possibly indicating a more favorable water supply of beech in diverse stands. Contrary to expectation, trees subject to more intense competition by neighboring trees (measured by Hegyi’s competition index) had lower δ¹³C values in their tree rings, which is thought to reflect denser canopies being linked to increased shading. We conclude that tree ring δ¹³C time series represent combined archives of climate variability, stand history and neighborhood effects on tree physiology and growth that may add valuable information to that obtained from conventional tree ring analysis.     

Measurements of radioactivity in environmental samples from the Southern Urals

A region between Chelyabinsk and Ekaterinburg in the Southern Urals has been heavily contaminated due to operational and accidental releases from the first Soviet plutonium production facility Mayak. In 1992 and 1993, the German Federal Office for Radiation Protection organized a measuring campaign involving two Russian institutes to assist with the validation of former Soviet measurement data. The results of this measuring campaign are reported here. Environmental samples were collected from areas affected by significant radioactive releases into the Techa river, which started in 1948, and by fallout from the explosion of a fission product storage tank in 1957. Soil, sediment, water, milk and food samples were independently analysed for ⁹⁰Sr, ¹³⁷Cs and plutonium by the three institutes involved. This paper presents data on the present levels of environmental radioactivity. The highest contamination of areas accessible to the local population was found in the vicinity of the Techa river around Muslumovo. Activity concentration of floodplain samples reached up to 37 000 Bq ⋅ kg^{–1 137}Cs, 5 600 Bq ⋅ kg^{–1 90}Sr and 9.9 Bq ⋅ kg^–1 Pu. Milk and potatoes from private farms in Muslumovo showed low activity in the range from 0.7 Bq ⋅ kg^–1 to 25 Bq ⋅ kg^{–1 90}Sr. The results of the three independent measurement teams showed sufficient agreement. One Russian laboratory obtained plutonium activities that exceeded the results of the other laboratories by about 20%. Contrary to the International Chernobyl Project, there was no overestimation of ⁹⁰Sr activities in the Russian analyses. Therefore, the validity of earlier data sets acquired with same methodology and quality control can be considered a valuable basis for further assessments and for dose reconstruction in epidemiological projects. Received: 18 July 1997 / Accepted in revised form: 19 December 1997     

Risk estimates for radiation-induced cancer – the epidemiological evidence

The risk of low-dose radiation exposures has – for a variety of reasons – been highly politicised. This has led to a frequently exaggerated perception of the potential health effects, and to lasting public controversies. A balanced view requires a critical reassessment of the epidemiological basis of current assumptions. There is reliable quantitative information available on the increase of cancer rates due to moderate and high doses. This provides a firm basis for the derivation of probabilities of causation, e.g. after high radiation exposures. For small doses or dose rates, the situation is entirely different: potential increases of cancer rates remain hidden below the statistical fluctuations of normal rates, and the molecular mechanisms of cancerogenesis are not sufficiently well known to allow numerical predictions. Risk coefficients for radiation protection must, therefore, be based on the uncertain extrapolation of observations obtained at moderate or high doses. While extrapolation is arbitrary, it is, nevertheless, used and mostly with the conservative assumption of a linear dose dependence with no threshold (LNT model). All risk estimates are based on this hypothesis. They are, thus, virtual guidelines, rather than firm numbers. The observations on the A-bomb survivors are still the major source of information on the health effects of comparatively small radiation doses. A fairly direct inspection of the data shows that the solid cancer mortality data of the A-bomb survivors are equally consistent with linearity in dose and with reduced effectiveness at low doses. In the leukemia data a reduction is strongly indicated. With one notable exception – leukemia after prenatal exposure – these observations are in line with a multitude of observations in groups of persons exposed for medical reasons. The low-dose effects of densely ionizing radiations – such as alpha-particles from radon decay products or high-energy neutrons – are a separate important issue. For neutrons, there is little epidemiological information. This has facilitated exaggerated claims of high neutron effects with reference to alleged dangers from transports of reactor fuel. However, in spite of limited information, it can be shown that the data from Hiroshima exclude the stated claims. New dosimetric information on neutrons may turn out to be highly informative with regard to an upper limit for the potential effects of neutrons and equally with regard to a reassessment – and a possible reduction – of risk estimates for gamma-rays. Received: 13 November 1999 / Accepted in revised form: 13 December 1999     

Biology of the spiderChiracanthium mildei [Arachnida: Clubionidae]

The biology ofChiracanthium mildei L. Koch was studied under standardized laboratory conditions (24±1°C, 55–60% RH). Specimens were reared from eggs, with 1- to 6-day-oldSpodoptera larvae serving as prey throughout their life cycle. Biological studies included an investigation of the rate of development, life cycle, reproductive potential and behavior, as well as the influence of certain environmental factors on these parameters. Under standard laboratory conditions,C. mildei showed 87% survival from egg to functional fertility. Males required a mean of 182 (137–207) days after hatching to reach maturity, became adults following 7–8 molts, and lived for an average of 73 days as adults. Females required a mean of 231 (191–286) days after hatching to mature, reached adulthood after 9–10 molts, and lived for an average of 240 days as adults. Females were found to mate only once and to oviposit from 1 to 5 times (average 1.8), at 30-day intervals. They produced a mean of 35 eggs in the 1st hatch and 31 eggs in the 2nd.

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Résumé La biologie de l'araignéeChiracanthium mildei L. Koch a été étudiée au laboratoire (24±1°C. 55–60% H.R.). Les élevages ont été conduits à partir des œufs, avec des larves deSpodoptera de 1 à 6 j fournies comme proies pendant toute la durée du cycle évolutif. Les études biologiques ont porté sur la vitesse de développement, le cycle évolutif, le potentiel et le comportement de reproduction, ainsi que sur l'influence de certains facteurs du milieu sur ces paramètres. Dans les conditions du laboratoire, le taux de survie deC. mildei fut de 87% de l'œuf à la maturité sexuelle. Chez les males la maturité est atteinte en moyenne 182 j (137–207) après l'éclosion de l'œuf. Ils deviennent adultes après 7 ou 8 mues et vivent en moyenne 73 j. Chez les femelles on compte une moyenne de 231 j (191–386) de l'éclosion de l'œuf à la maturité. Elles deviennent adultes après 9 ou 10 mues et vivent en moyenne 240 j. Les femelles s'accouplent 1 fois mais pondent 1 à 5 fois (moyenne 1,8) en 30 j. Leur fécondité moyenne est de 35 œufs lors de la 1^re ponte et de 31 œufs pour la 2^e.

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Contribution from the Agricultural Research Organization, Bet Dagan, Israel. No. 203-E, 1979 series.     

Macrobenthic fauna of the Franz Josef Land archipelago

Benthic fauna of the deeper waters (50–320 m) of the Franz Josef Land archipelago sampled in August 1992 using standard western techniques is described and compared with earlier Russian studies of the archipelago. Three faunal assemblages are recognised at depth ranges between 50–150, 150–300, and >300 m depth. Their distributions are related to depth and to different water masses derived from a mixture of Barents Sea water entering from the south at intermediate depths (20–150 m), and Atlantic water from the north below 300 m. The recorded faunal diversity and biomass is as high as or higher than that from comparable Arctic and northern boreal areas. Comparisons are also made with a complimentary Russian survey in the same area using different techniques. The Russian work collected larger organisms most effectively, whereas the present work recorded the smaller taxa more efficiently. Russian surveys provide complementary data to western studies, but care must be taken when comparing studies as they reflect biases in sampling gear and scientific emphasis. These data intercalibrations are important as Russian archives contain a wealth of information that, if used correctly in association with western data sources, will be useful in environmental monitoring studies as human activities increase in the Eurasian Arctic. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

4D prediction of protein <Superscript>1</Superscript>H chemical shifts

A 4D approach for protein ¹H chemical shift prediction was explored. The 4th dimension is the molecular flexibility, mapped using molecular dynamics simulations. The chemical shifts were predicted with a principal component model based on atom coordinates from a database of 40 protein structures. When compared to the corresponding non-dynamic (3D) model, the 4th dimension improved prediction by 6–7%. The prediction method achieved RMS errors of 0.29 and 0.50 ppm for Hα and HN shifts, respectively. However, for individual proteins the RMS errors were 0.17–0.34 and 0.34–0.65 ppm for the Hα and HN shifts, respectively. X-ray structures gave better predictions than the corresponding NMR structures, indicating that chemical shifts contain invaluable information about local structures. The ¹H chemical shift prediction tool 4DSPOT is available from .     

The Effect of DNA Repair Defects on Reproductive Performance in Nucleotide Excision Repair (NER) Mouse Models: An Epidemiological Approach

In this study, we used an epidemiological approach to analyze an animal database of DNA repair deficient mice on reproductive performance in five Nucleotide Excision Repair (NER) mutant mouse models on a C57BL/6 genetic background, namely CSA, CSB, XPA, XPC [models for the human DNA repair disorders Cockayne Syndrome (CS) and xeroderma pigmentosum (XP), respectively] and mHR23B (not associated with human disease). This approach allowed us to detect and quantify reproductive effects based on a relatively small number of matings. We measured and quantified the scale of the effect between factors that might influence reproductive performance (i.e. age at co-housing, seasons) and reproductive parameters (i.e. litter size and pairing-to-birth interval –‘pbi’). Besides, we detected and quantified the differences in reproductive performance between wild type mice and heterozygous/homozygous NER mutant mice. From our analyses, we found impaired reproduction in heterozygous and homozygous knock out mice; in particular, reduced litter size and lengthened pbi was related to the NER mutation-mHR23B, in heterozygous couples, even if they were otherwise phenotypically normal. Heterozygous mHR23B couples produced a 6.6-fold lower number of mHR23B^−/− pups than indicated by Mendelian expectation; other genetic deficiencies studied were not statistically significant from each other or wild type controls. We concluded that careful epidemiological evaluations by analysis of animal database could provide reliable information on reproductive performance and detect deviations that would remain unnoticed without this. Also, some managerial aspects of mouse breeding could be evaluated.