The effects of radiation upon circulating lymphocytes have been measured by two independent means, one monitoring the level of cytogenetic damage appearing in these cells, the other monitoring changes in their proliferative response to stimulation in culture by phytohaemagglutin (PHA). Response to PHA can be expressed quantitatively as lymphocyte replicating ability (LRA), i.e. the degree of 3 H-thymidine uptake measured under standardized conditions. Varying degrees of depression of LRA have been noted within a group of patients undergoing a wide range of radiotherapeutic procedures. The concomitant cytogenetic studies indicate that although cells bearing radiation damage do persist in the circulation after irradiation their numbers are insufficient to account for the marked reduction seen at the same time in LRA. It appears that the reduction is largely due to a fall in the number of thymusdependent lymphocytes in the circulatory pool.

BackgroundGestational diabetes mellitus (GDM) is one of the most common complications of pregnancy. Left untreated or poorly controlled, GDM results in adverse infant outcomes such as large for gestational age (LGA). This study aims to identify nonglycemic maternal and fetal factors predictive of LGA outcomes in pregnancies complicated by diet‐managed GDM.MethodsThis was a retrospective cohort study of singleton pregnancies complicated by diet‐managed GDM from 2004 to 2015. Multiple logistic regression analysis was performed on maternal and perinatal factors to identify risk factors for LGA. In addition, a subset univariate analysis was conducted for pregnancies in which fetal ultrasound abdominal circumference measurements were available at gestational weeks 18 to 22, 24 to 28, and 29 to 33.ResultsA total of 1064 women were included, delivering 123 LGA infants. Women with higher parity (odds ratio [OR] 1.44; CI, 1.23‐1.68; P < .001) and higher prepregnancy body mass index (BMI) (OR 1.09; CI, 1.06‐1.12; P < .001) were more likely to have LGA infants. Maternal smoking (OR 0.30; CI, 0.14‐0.62; P = .001) and higher gestational age at birth (OR 0.91; CI, 0.84‐0.99; P = .018) were associated with reduced risk. Subset univariate analysis showed that fetal abdominal circumference measurements at weeks 24 to 28 and 29 to 33 beyond the 75th percentile (OR 5.92 and 13.74, respectively) and 90th percentile (OR 4.57 and 15.89, respectively) were highly predictive of LGA.ConclusionsParity, smoking status, maternal BMI, gestational age, and ultrasound fetal abdominal circumference measurements were identified as useful predictors of LGA. Presence of these predictors may prompt closer monitoring of pregnancy and early therapeutic intervention to improve management and reduce the risk of adverse fetal and maternal outcomes.

SUMMARY Chromosome aberration analysis provides a biological method of assessing absorbed radiation dose. This paper describes the types of aberration brought about in the chromosomes of lymphocytes by radiation‐induced chromosomal breaks, how they can be displayed and related to IN VITRO radiation exposure of blood lymphocyte cultures. A calibration chart incorporating these IN VITRO dose response relationships enables the IN VIVO exposure of individuals during radiotherapy to be compared with the dose giving the same number of chromosome aberrations brought about by IN VITRO irradiation of blood lymphocytes. Radiotherapeutic exposure in its scientifically defined exactness to known volumes of different body regions enables the accumulation of information invaluable to the determination of the amount of radiation received in those accidentally exposed.

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