Robert L. Brent

Bio: Robert L. Brent is an academic researcher from Alfred I. duPont Hospital for Children. The author has contributed to research in topics: Yolk sac & Offspring. The author has an hindex of 49, co-authored 325 publications receiving 10672 citations. Previous affiliations of Robert L. Brent include DuPont & Wilmington University.

Toxicity testing in the 21st century: a vision and a strategy

Abstract: With the release of the landmark report Toxicity Testing in the 21st Century: A Vision and a Strategy, the U.S. National Academy of Sciences, in 2007, precipitated a major change in the way toxicity testing is conducted. It envisions increased efficiency in toxicity testing and decreased animal usage by transitioning from current expensive and lengthy in vivo testing with qualitative endpoints to in vitro toxicity pathway assays on human cells or cell lines using robotic high-throughput screening with mechanistic quantitative parameters. Risk assessment in the exposed human population would focus on avoiding significant perturbations in these toxicity pathways. Computational systems biology models would be implemented to determine the dose-response models of perturbations of pathway function. Extrapolation of in vitro results to in vivo human blood and tissue concentrations would be based on pharmacokinetic models for the given exposure condition. This practice would enhance human relevance of test results, and would cover several test agents, compared to traditional toxicological testing strategies. As all the tools that are necessary to implement the vision are currently available or in an advanced stage of development, the key prerequisites to achieving this paradigm shift are a commitment to change in the scientific community, which could be facilitated by a broad discussion of the vision, and obtaining necessary resources to enhance current knowledge of pathway perturbations and pathway assays in humans and to implement computational systems biology models. Implementation of these strategies would result in a new toxicity testing paradigm firmly based on human biology.

Radiation risk to children from computed tomography

Abstract: Imaging studies that use ionizing radiation are an essential tool for the evaluation of many disorders of childhood. Ionizing radiation is used in radiography, fluoroscopy, angiography, and computed tomography scanning. Computed tomography is of particular interest because of its relatively high radiation dose and wide use. Consensus statements on radiation risk suggest that it is reasonable to act on the assumption that low-level radiation may have a small risk of causing cancer. The medical community should seek ways to decrease radiation exposure by using radiation doses as low as reasonably achievable and by performing these studies only when necessary. There is wide agreement that the benefits of an indicated computed tomography scan far outweigh the risks. Pediatric health care professionals’ roles in the use of computed tomography on children include deciding when a computed tomography scan is necessary and discussing the risk with patients and families. Radiologists should be a source of consultation when forming imaging strategies and should create specific protocols with scanning techniques optimized for pediatric patients. Families and patients should be encouraged to ask questions about the risks and benefits of computed tomography scanning. The information in this report is provided to aid in decision-making and discussions with the health care team, patients, and families.

Environmental Causes of Human Congenital Malformations: The Pediatrician’s Role in Dealing With These Complex Clinical Problems Caused by a Multiplicity of Environmental and Genetic Factors

Abstract: There have been amazing advances in embryology, teratology, reproductive biology, genetics, and epidemiology in the past 50 years that have provided scientists and clinicians with a better perspective on the causes of congenital malformations. We still cannot provide the families of children with malformations a definitive diagnosis and cause in every instance. The purpose of this article is to inform pediatricians about environmental drugs, chemicals, and physical agents that have been documented to produce congenital malformations and reproductive effects and to indicate that the multitude of teratogenic agents account for only a small proportion of malformations. The most common known cause is genetic, but the largest group, unfortunately, There have been amazing advances in embryology, teratology, reproductive biology, genetics, and epidemiology in the past 50 years that have provided scientists and clinicians with a better perspective on the causes of congenital malformations. We still cannot provide the families of children with malformations a definitive diagnosis and cause in every instance. The purpose of this article is to inform pediatricians about environmental drugs, chemicals, and physical agents that have been documented to produce congenital malformations and reproductive effects and to indicate that the multitude of teratogenic agents account for only a small proportion of malformations. The most common known cause is genetic, but the largest group, unfortunately, is unknown. There are a number of important clinical rules that are important for clinicians to use when determining the cause of their patient's congenital malformations: 1. No teratogenic agent should be described qualitatively as a teratogen, because a teratogenic exposure includes not only the agent but also the dose and the time in pregnancy when the exposure has to occur. 2. Even agents that have been demonstrated to result in malformations cannot produce every type of malformation. Known teratogens may be presumptively implicated by the spectrum of malformations that they produce. It is easier to exclude an agent as a cause of birth defects than to conclude definitively that it was responsible for birth defects, because of the existence of genocopies of some teratogenic syndromes. 3. When evaluating the risk of exposures, the dose is a crucial component in determining the risk. Teratogenic agents follow a toxicologic dose-response curve. This means that each teratogen has a threshold dose below which there is no risk of teratogenesis, no matter when in pregnancy the exposure occurred. 4. The evaluation of a child with congenital malformations cannot be performed adequately unless it is approached with the same scholarship and intensity as the evaluation of any other complicated medical problem. 5. Each physician must recognize the consequences of providing erroneous reproductive risks to pregnant women who are exposed to drugs and chemicals during pregnancy or alleging that a child's malformations are attributable to an environmental agent without performing a complete and scholarly evaluation. 6. Unfortunately, clinical teratology and clinical genetics is not emphasized in medical school and residency education programs, but pediatricians have a multitude of educational aids to assist them in their evaluations, which includes consultations with clinical teratologists and geneticists, the medical literature, and the OMIM web site.

sources and effects of ionizing radiation

Abstract: NOTE The report of the Committee without its annexes appears as Official Records of the General Assembly, Sixty-third Session, Supplement No. 46. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The country names used in this document are, in most cases, those that were in use at the time the data were collected or the text prepared. In other cases, however, the names have been updated, where this was possible and appropriate, to reflect political changes. Scientific Annexes Annex A. Medical radiation exposures Annex B. Exposures of the public and workers from various sources of radiation INTROdUCTION 1. In the course of the research and development for and the application of atomic energy and nuclear technologies, a number of radiation accidents have occurred. Some of these accidents have resulted in significant health effects and occasionally in fatal outcomes. The application of technologies that make use of radiation is increasingly widespread around the world. Millions of people have occupations related to the use of radiation, and hundreds of millions of individuals benefit from these uses. Facilities using intense radiation sources for energy production and for purposes such as radiotherapy, sterilization of products, preservation of foodstuffs and gamma radiography require special care in the design and operation of equipment to avoid radiation injury to workers or to the public. Experience has shown that such technology is generally used safely, but on occasion controls have been circumvented and serious radiation accidents have ensued. 2. Reviews of radiation exposures from accidents have been presented in previous UNSCEAR reports. The last report containing an exclusive chapter on exposures from accidents was the UNSCEAR 1993 Report [U6]. 3. This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices. Its conclusions are to be seen in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation. 4. The Committee's evaluations of public, occupational and medical diagnostic exposures are mostly concerned with chronic exposures of …

The Environmental Protection Agency

Abstract: The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

Creatine and Creatinine Metabolism

Abstract: The goal of this review is to present a comprehensive survey of the many intriguing facets of creatine (Cr) and creatinine metabolism, encompassing the pathways and regulation of Cr biosynthesis an...

The Toxicology of Mercury and Its Chemical Compounds

Abstract: This review covers the toxicology of mercury and its compounds. Special attention is paid to those forms of mercury of current public health concern. Human exposure to the vapor of metallic mercury dates back to antiquity but continues today in occupational settings and from dental amalgam. Health risks from methylmercury in edible tissues of fish have been the subject of several large epidemiological investigations and continue to be the subject of intense debate. Ethylmercury in the form of a preservative, thimerosal, added to certain vaccines, is the most recent form of mercury that has become a public health concern. The review leads to general discussion of evolutionary aspects of mercury, protective and toxic mechanisms, and ends on a note that mercury is still an "element of mystery."

ESC Guidelines on the management of cardiovascular diseases during pregnancy: the Task Force on the Management of Cardiovascular Diseases during Pregnancy of the European Society of Cardiology (ESC).

Abstract: Table 1. Classes of recommendation Table 2. Levels of evidence Table 3. Estimated fetal and maternal effective doses for various diagnostic and interventional radiology procedures Table 4. Predictors of maternal cardiovascular events and risk score from the CARPREG study Table 5. Predictors of maternal cardiovascular events identified in congential heart diseases in the ZAHARA and Khairy study Table 6. Modified WHO classification of maternal cardiovascular risk: principles Table 7. Modified WHO classification of maternal cardiovascular risk: application Table 8. Maternal predictors of neonatal events in women with heart disease Table 9. General recommendations Table 10. Recommendations for the management of congenital heart disease Table 11. Recommendations for the management of aortic disease Table 12. Recommendations for the management of valvular heart disease Table 13. Recommendations for the management of coronary artery disease Table 14. Recommendations for the management of cardiomyopathies and heart failure Table 15. Recommendations for the management of arrhythmias Table 16. Recommendations for the management of hypertension Table 17. Check list for risk factors for venous thrombo-embolism Table 18. Prevalence of congenital thrombophilia and the associated risk of venous thrombo-embolism during pregnancy Table 19. Risk groups according to risk factors: definition and preventive measures Table 20. Recommendations for the prevention and management of venous thrombo-embolism in pregnancy and puerperium Table 21. Recommendations for drug use ABPM : ambulatory blood pressure monitoring ACC : American College of Cardiology ACE : angiotensin-converting enzyme ACS : acute coronary syndrome AF : atrial fibrillation AHA : American Heart Association aPTT : activated partial thromboplastin time ARB : angiotensin receptor blocker AS : aortic stenosis ASD : atrial septal defect AV : atrioventricular AVSD : atrioventricular septal defect BMI : body mass index BNP : B-type natriuretic peptide BP : blood pressure CDC : Centers for Disease Control CHADS : congestive heart failure, hypertension, age (>75 years), diabetes, stroke CI : confidence interval CO : cardiac output CoA : coarction of the aorta CT : computed tomography CVD : cardiovascular disease DBP : diastolic blood pressure DCM : dilated cardiomyopathy DVT : deep venous thrombosis ECG : electrocardiogram EF : ejection fraction ESC : European Society of Cardiology ESH : European Society of Hypertension ESICM : European Society of Intensive Care Medicine FDA : Food and Drug Administration HCM : hypertrophic cardiomyopathy ICD : implantable cardioverter-defibrillator INR : international normalized ratio i.v. : intravenous LMWH : low molecular weight heparin LV : left ventricular LVEF : left ventricular ejection fraction LVOTO : left ventricular outflow tract obstruction MRI : magnetic resonance imaging MS : mitral stenosis NT-proBNP : N-terminal pro B-type natriuretic peptide NYHA : New York Heart Association OAC : oral anticoagulant PAH : pulmonary arterial hypertension PAP : pulmonary artery pressure PCI : percutaneous coronary intervention PPCM : peripartum cardiomyopathy PS : pulmonary valve stenosis RV : right ventricular SBP : systolic blood pressure SVT : supraventricular tachycardia TGA : complete transposition of the great arteries TR : tricuspid regurgitation UFH : unfractionated heparin VSD : ventricular septal defect VT : ventricular tachycardia VTE : venous thrombo-embolism WHO : World Health Organization Guidelines summarize and evaluate all available evidence, at the time of the writing process, on a particular issue with the aim of assisting physicians in selecting the best management strategies for an individual patient, with a given condition, taking into account the impact on outcome, as well as the risk–benefit ratio of particular diagnostic or therapeutic means. Guidelines are no substitutes but are complements for textbooks and cover the European Society of Cardiology (ESC) Core Curriculum topics. Guidelines and recommendations should help the …