Cellular Radiosensitivity: How much better do we understand it?

Purpose: Ionizing radiation exposure gives rise to a variety of lesions in DNA that result in genetic instability and potentially tumorigenesis or cell death. Radiation extends its effects on DNA by direct interaction or by radiolysis of H2O that generates free radicals or aqueous electrons capable of interacting with and causing indirect damage to DNA. While the various lesions arising in DNA after radiation exposure can contribute to the mutagenising effects of this agent, the potentially most damaging lesion is the DNA double strand break (DSB) that contributes to genome instability and/or cell death. Thus in many cases failure to recognise and/or repair this lesion determines the radiosensitivity status of the cell. DNA repair mechanisms including homologous recombination (HR) and non-homologous end-joining (NHEJ) have evolved to protect cells against DNA DSB. Mutations in proteins that constitute these repair pathways are characterised by radiosensitivity and genome instability. Defects in a number of these proteins also give rise to genetic disorders that feature not only genetic instability but also immunodeficiency, cancer predisposition, neurodegeneration and other pathologies. Conclusions: In the past fifty years our understanding of the cellular response to radiation damage has advanced enormously with insight being gained from a wide range of approaches extending from more basic early studies to the sophisticated approaches used today. In this review we discuss our current understanding of the impact of radiation on the cell and the organism gained from the array of past and present studies and attempt to provide an explanation for what it is that determines the response to radiation

The relationship among oceanography, prey fields, and beaked whale foraging habitat in the Tongue of the Ocean

This article is distributed under the terms of the Creative Commons CC0 public domain dedication. The definitive version was published in PLoS One 6 (2011): e19269, doi:10.1371/journal.pone.0019269.Beaked whales, specifically Blainville's (Mesoplodon densirostris) and Cuvier's (Ziphius cavirostris), are known to feed in the Tongue of the Ocean, Bahamas. These whales can be reliably detected and often localized within the Atlantic Undersea Test and Evaluation Center (AUTEC) acoustic sensor system. The AUTEC range is a regularly spaced bottom mounted hydrophone array covering >350 nm2 providing a valuable network to record anthropogenic noise and marine mammal vocalizations. Assessments of the potential risks of noise exposure to beaked whales have historically occurred in the absence of information about the physical and biological environments in which these animals are distributed. In the fall of 2008, we used a downward looking 38 kHz SIMRAD EK60 echosounder to measure prey scattering layers concurrent with fine scale turbulence measurements from an autonomous turbulence profiler. Using an 8 km, 4-leaf clover sampling pattern, we completed a total of 7.5 repeat surveys with concurrently measured physical and biological oceanographic parameters, so as to examine the spatiotemporal scales and relationships among turbulence levels, biological scattering layers, and beaked whale foraging activity. We found a strong correlation among increased prey density and ocean vertical structure relative to increased click densities. Understanding the habitats of these whales and their utilization patterns will improve future models of beaked whale habitat as well as allowing more comprehensive assessments of exposure risk to anthropogenic sound.The data collection and analysis was funded by the Office of Naval Research as N00014-08-1-1162

Primary intestinal lymphangiectasia (Waldmann's disease)

Primary intestinal lymphangiectasia (PIL) is a rare disorder characterized by dilated intestinal lacteals resulting in lymph leakage into the small bowel lumen and responsible for protein-losing enteropathy leading to lymphopenia, hypoalbuminemia and hypogammaglobulinemia. PIL is generally diagnosed before 3 years of age but may be diagnosed in older patients. Prevalence is unknown. The main symptom is predominantly bilateral lower limb edema. Edema may be moderate to severe with anasarca and includes pleural effusion, pericarditis or chylous ascites. Fatigue, abdominal pain, weight loss, inability to gain weight, moderate diarrhea or fat-soluble vitamin deficiencies due to malabsorption may also be present. In some patients, limb lymphedema is associated with PIL and is difficult to distinguish lymphedema from edema. Exsudative enteropathy is confirmed by the elevated 24-h stool α1-antitrypsin clearance. Etiology remains unknown. Very rare familial cases of PIL have been reported. Diagnosis is confirmed by endoscopic observation of intestinal lymphangiectasia with the corresponding histology of intestinal biopsy specimens. Videocapsule endoscopy may be useful when endoscopic findings are not contributive. Differential diagnosis includes constrictive pericarditis, intestinal lymphoma, Whipple's disease, Crohn's disease, intestinal tuberculosis, sarcoidosis or systemic sclerosis. Several B-cell lymphomas confined to the gastrointestinal tract (stomach, jejunum, midgut, ileum) or with extra-intestinal localizations were reported in PIL patients. A low-fat diet associated with medium-chain triglyceride supplementation is the cornerstone of PIL medical management. The absence of fat in the diet prevents chyle engorgement of the intestinal lymphatic vessels thereby preventing their rupture with its ensuing lymph loss. Medium-chain triglycerides are absorbed directly into the portal venous circulation and avoid lacteal overloading. Other inconsistently effective treatments have been proposed for PIL patients, such as antiplasmin, octreotide or corticosteroids. Surgical small-bowel resection is useful in the rare cases with segmental and localized intestinal lymphangiectasia. The need for dietary control appears to be permanent, because clinical and biochemical findings reappear after low-fat diet withdrawal. PIL outcome may be severe even life-threatening when malignant complications or serous effusion(s) occur

Planned delivery for pre-eclampsia between 34 and 37 weeks of gestation: the PHOENIX RCT.

BACKGROUND: In women with late preterm pre-eclampsia (i.e. at 34+0 to 36+6 weeks' gestation), the optimal delivery time is unclear because limitation of maternal-fetal disease progression needs to be balanced against infant complications. The aim of this trial was to determine whether or not planned earlier initiation of delivery reduces maternal adverse outcomes without substantial worsening of perinatal or infant outcomes, compared with expectant management, in women with late preterm pre-eclampsia. METHODS: We undertook an individually randomised, triple non-masked controlled trial in 46 maternity units across England and Wales, with an embedded health economic evaluation, comparing planned delivery and expectant management (usual care) in women with late preterm pre-eclampsia. The co-primary maternal outcome was a maternal morbidity composite or recorded systolic blood pressure of ≥ 160 mmHg (superiority hypothesis). The co-primary short-term perinatal outcome was a composite of perinatal deaths or neonatal unit admission (non-inferiority hypothesis). Analyses were by intention to treat, with an additional per-protocol analysis for the perinatal outcome. The primary 2-year infant neurodevelopmental outcome was measured using the PARCA-R (Parent Report of Children's Abilities-Revised) composite score. The planned sample size of the trial was 900 women; the trial is now completed. We undertook two linked substudies. RESULTS: Between 29 September 2014 and 10 December 2018, 901 women were recruited; 450 women [448 women (two withdrew consent) and 471 infants] were allocated to planned delivery and 451 women (451 women and 475 infants) were allocated to expectant management. The incidence of the co-primary maternal outcome was significantly lower in the planned delivery group [289 (65%) women] than in the expectant management group [338 (75%) women] (adjusted relative risk 0.86, 95% confidence interval 0.79 to 0.94; p = 0.0005). The incidence of the co-primary perinatal outcome was significantly higher in the planned delivery group [196 (42%) infants] than in the expectant management group [159 (34%) infants] (adjusted relative risk 1.26, 95% confidence interval 1.08 to 1.47; p = 0.0034), but indicators of neonatal morbidity were similar in both groups. At 2-year follow-up, the mean PARCA-R scores were 89.5 points (standard deviation 18.2 points) for the planned delivery group (290 infants) and 91.9 points (standard deviation 18.4 points) for the expectant management group (256 infants), both within the normal developmental range (adjusted mean difference -2.4 points, 95% confidence interval -5.4 to 0.5 points; non-inferiority p = 0.147). Planned delivery was significantly cost-saving (-£2711, 95% confidence interval -£4840 to -£637) compared with expectant management. There were nine serious adverse events in the planned delivery group and 12 in the expectant management group. CONCLUSION: In women with late preterm pre-eclampsia, planned delivery reduces short-term maternal morbidity compared with expectant management, with more neonatal unit admissions related to prematurity but no indicators of greater short-term neonatal morbidity (such as need for respiratory support). At 2-year follow-up, around 60% of parents reported follow-up scores. Average infant development was within the normal range for both groups; the small between-group mean difference in PARCA-R scores is unlikely to be clinically important. Planned delivery was significantly cost-saving to the health service. These findings should be discussed with women with late preterm pre-eclampsia to allow shared decision-making on timing of delivery. LIMITATIONS: Limitations of the trial include the challenges of finding a perinatal outcome that adequately represented the potential risks of both groups and a maternal outcome that reflects the multiorgan manifestations of pre-eclampsia. The incidences of maternal and perinatal primary outcomes were higher than anticipated on the basis of previous studies, but this did not limit interpretation of the analysis. The trial was limited by a higher loss to follow-up rate than expected, meaning that the extent and direction of bias in outcomes (between responders and non-responders) is uncertain. A longer follow-up period (e.g. up to 5 years) would have enabled us to provide further evidence on long-term infant outcomes, but this runs the risk of greater attrition and increased expense. FUTURE WORK: We identified a number of further questions that could be prioritised through a formal scoping process, including uncertainties around disease-modifying interventions, prognostic factors, longer-term follow-up, the perspectives of women and their families, meta-analysis with other studies, effect of a similar intervention in other health-care settings, and clinical effectiveness and cost-effectiveness of other related policies around neonatal unit admission in late preterm birth. TRIAL REGISTRATION: The trial was prospectively registered as ISRCTN01879376. FUNDING: This project was funded by the National Institute for Health and Care Research ( NIHR ) Health Technology Assessment programme and will be published in Health Technology Assessment. See the NIHR Journals Library website for further project information

Left Atrial Mechanics Following Preeclamptic Pregnancy.

BACKGROUND: Preterm preeclampsia is a pregnancy complication associated with myocardial dysfunction and premature cardiovascular disease morbidity and mortality. Left atrial (LA) strain is a noninvasive index of left ventricular end diastolic pressure and an early marker of heart failure risk. This study aimed to evaluate LA strain during the postpartum period in participants with and without preterm preeclampsia and to assess whether this varied in the presence of hypertension and/or cardiac dysfunction. METHODS: In this longitudinal cohort study, 321 women from 28 hospitals with preterm preeclampsia (cases) underwent cardiovascular assessment 6 months postpartum. This is a secondary analysis of the PHOEBE study (ISRCTN01879376). An uncomplicated pregnancy control group (n=30) was recruited from a single center for comparison. A full cross-sectional transthoracic echocardiogram was performed, and from these images, the myocardial strain of the left atrium, including reservoir, conduit, and contractile strain, as well as LA stiffness, were calculated. RESULTS: At 6 months postpartum, compared with controls, prior preeclampsia was associated with a significantly attenuated LA reservoir, conduit, and contractile strain, as well as increased LA stiffness (all P<0.001). LA strain was further reduced in preeclamptic women who had and had not developed hypertension, systolic, or diastolic dysfunction at 6 months postpartum (all P<0.05). CONCLUSIONS: LA mechanics were significantly attenuated at 6 months postpartum in participants with preterm preeclampsia, whether or not they remained hypertensive or had evidence of ventricular dysfunction. Further studies are needed to determine whether postnatal LA strain may identify women at greater risk for future cardiovascular disease

Planned delivery for pre-eclampsia between 34 and 37 weeks of gestation: the PHOENIX RCT

Background In women with late preterm pre-eclampsia (i.e. at 34+0 to 36+6 weeks’ gestation), the optimal delivery time is unclear because limitation of maternal–fetal disease progression needs to be balanced against infant complications. The aim of this trial was to determine whether or not planned earlier initiation of delivery reduces maternal adverse outcomes without substantial worsening of perinatal or infant outcomes, compared with expectant management, in women with late preterm pre-eclampsia. Methods We undertook an individually randomised, triple non-masked controlled trial in 46 maternity units across England and Wales, with an embedded health economic evaluation, comparing planned delivery and expectant management (usual care) in women with late preterm pre-eclampsia. The co-primary maternal outcome was a maternal morbidity composite or recorded systolic blood pressure of ≥ 160 mmHg (superiority hypothesis). The co-primary short-term perinatal outcome was a composite of perinatal deaths or neonatal unit admission (non-inferiority hypothesis). Analyses were by intention to treat, with an additional per-protocol analysis for the perinatal outcome. The primary 2-year infant neurodevelopmental outcome was measured using the PARCA-R (Parent Report of Children’s Abilities-Revised) composite score. The planned sample size of the trial was 900 women; the trial is now completed. We undertook two linked substudies. Results Between 29 September 2014 and 10 December 2018, 901 women were recruited; 450 women [448 women (two withdrew consent) and 471 infants] were allocated to planned delivery and 451 women (451 women and 475 infants) were allocated to expectant management. The incidence of the co-primary maternal outcome was significantly lower in the planned delivery group [289 (65%) women] than in the expectant management group [338 (75%) women] (adjusted relative risk 0.86, 95% confidence interval 0.79 to 0.94; p = 0.0005). The incidence of the co-primary perinatal outcome was significantly higher in the planned delivery group [196 (42%) infants] than in the expectant management group [159 (34%) infants] (adjusted relative risk 1.26, 95% confidence interval 1.08 to 1.47; p = 0.0034), but indicators of neonatal morbidity were similar in both groups. At 2-year follow-up, the mean PARCA-R scores were 89.5 points (standard deviation 18.2 points) for the planned delivery group (290 infants) and 91.9 points (standard deviation 18.4 points) for the expectant management group (256 infants), both within the normal developmental range (adjusted mean difference –2.4 points, 95% confidence interval –5.4 to 0.5 points; non-inferiority p = 0.147). Planned delivery was significantly cost-saving (–£2711, 95% confidence interval –£4840 to –£637) compared with expectant management. There were nine serious adverse events in the planned delivery group and 12 in the expectant management group. Conclusion In women with late preterm pre-eclampsia, planned delivery reduces short-term maternal morbidity compared with expectant management, with more neonatal unit admissions related to prematurity but no indicators of greater short-term neonatal morbidity (such as need for respiratory support). At 2-year follow-up, around 60% of parents reported follow-up scores. Average infant development was within the normal range for both groups; the small between-group mean difference in PARCA-R scores is unlikely to be clinically important. Planned delivery was significantly cost-saving to the health service. These findings should be discussed with women with late preterm pre-eclampsia to allow shared decision-making on timing of delivery. Limitations Limitations of the trial include the challenges of finding a perinatal outcome that adequately represented the potential risks of both groups and a maternal outcome that reflects the multiorgan manifestations of pre-eclampsia. The incidences of maternal and perinatal primary outcomes were higher than anticipated on the basis of previous studies, but this did not limit interpretation of the analysis. The trial was limited by a higher loss to follow-up rate than expected, meaning that the extent and direction of bias in outcomes (between responders and non-responders) is uncertain. A longer follow-up period (e.g. up to 5 years) would have enabled us to provide further evidence on long-term infant outcomes, but this runs the risk of greater attrition and increased expense. Future work We identified a number of further questions that could be prioritised through a formal scoping process, including uncertainties around disease-modifying interventions, prognostic factors, longer-term follow-up, the perspectives of women and their families, meta-analysis with other studies, effect of a similar intervention in other health-care settings, and clinical effectiveness and cost-effectiveness of other related policies around neonatal unit admission in late preterm birth. Trial registration The trial was prospectively registered as ISRCTN01879376