Susceptibility to retroactive interference: The effect of context as a function of age and cognition.

Previous studies have shown that contextual cues improve memory performance and reduce interference in younger adults. However, it is not clear whether middle-aged and older adults can also benefit from contextual cues, or if this ability diminishes with ageing and cognitive decline. In order to test this question, we tested 69 middle-aged adults (aged 30-50 years) and 65 older adults (aged 65-85). Participants completed a retroactive interference paradigm with or without contextual cues. Cognitive functioning of older adults was assessed using the Montreal Cognitive Assessment, which is a sensitive and highly validated tool to detect cognitive decline in older age. The results showed that while middle-aged adults were able to benefit from context to improve recognition and reduce interference, older adults were not able to benefit from it. However, when we compared older adults with lower (<26) and higher (≥26) scores on the Montreal Cognitive Assessment, we found that older adults with high cognitive functioning could benefit from context advantage at retrieval to improve recognition compared to those with lower cognitive functioning. Yet, similar to older adults with lower cognitive functioning, they could not benefit from context advantage at encoding and hence were still susceptible to interference.

Comparing the Hematopoetic Syndrome Time Course in the NHP Animal Model to Radiation Accident Cases From the Database Search.

Since controlled clinical studies on drug administration for the acute radiation syndrome are lacking, clinical data of human radiation accident victims as well as experimental animal models are the main sources of information. This leads to the question of how to compare and link clinical observations collected after human radiation accidents with experimental observations in non-human primate (NHP) models. Using the example of granulocyte counts in the peripheral blood following radiation exposure, approaches for adaptation between NHP and patient databases on data comparison and transformation are introduced. As a substitute for studying the effects of administration of granulocyte-colony stimulating factor (G-CSF) in human clinical trials, the method of mathematical modeling is suggested using the example of G-CSF administration to NHP after total body irradiation.

Methadone maintenance patients show a selective deficit to reverse positive outcomes in drug-related conditions compared to medication free prolonged opiate abstinence.

BACKGROUND: Drug addiction is a chronic relapsing disease. Most users will relapse back to using drugs over and over again throughout their life. These relapses may become more frequent in the presence of contextual reminders. We aimed to examine associations between the ability to maintain a medication-free life-style and the capability to learn and reverse positive and negative stimulus-outcome associations in the presence of neutral and drug-related contextual reminders. METHODS: We conducted a highly unique comparison of former opiate-dependent individuals who are either medication free or methadone maintenance patients for the last ten years. Groups were matched for age, gender and education. Participants were tested on a novel partial reversal paradigm, which tests the ability to acquire and reverse stimulus-outcome associations in neutral and drug-related context. RESULTS: Both groups were equally able to acquire and reverse positive and negative outcomes in conditions of neutral context. However, methadone maintenance patients showed a selective deficit in reversing the outcomes of positive stimulus in drug-related context. Hence, after learning a positive stimulus-outcome association in one drug-related context, methadone maintenance patients struggled to learn that the same stimulus predicts negative outcome when presented later in a different drug-related context. CONCLUSIONS: Methadone maintenance patients demonstrate a selective difficulty to learn negative outcomes when exposed to a drug, but not neutral, related environment. The results may reflect the core mechanisms of addiction and provide a possible explanation for the inability of methadone maintenance patients to illicit drug abuse without the need of agonist treatment.

Mitigating the risk of radiation-induced cancers: limitations and paradigms in drug development.

The United States radiation medical countermeasures (MCM) programme for radiological and nuclear incidents has been focusing on developing mitigators for the acute radiation syndrome (ARS) and delayed effects of acute radiation exposure (DEARE), and biodosimetry technologies to provide radiation dose assessments for guiding treatment. Because a nuclear accident or terrorist incident could potentially expose a large number of people to low to moderate doses of ionising radiation, and thus increase their excess lifetime cancer risk, there is an interest in developing mitigators for this purpose. This article discusses the current status, issues, and challenges regarding development of mitigators against radiation-induced cancers. The challenges of developing mitigators for ARS include: the long latency between exposure and cancer manifestation, limitations of animal models, potential side effects of the mitigator itself, potential need for long-term use, the complexity of human trials to demonstrate effectiveness, and statistical power constraints for measuring health risks (and reduction of health risks after mitigation) following relatively low radiation doses (<0.75 Gy). Nevertheless, progress in the understanding of the molecular mechanisms resulting in radiation injury, along with parallel progress in dose assessment technologies, make this an opportune, if not critical, time to invest in research strategies that result in the development of agents to lower the risk of radiation-induced cancers for populations that survive a significant radiation exposure incident.

Linking the human response to unplanned radiation and treatment to the nonhuman primate response to controlled radiation and treatment.

A key difficulty in developing countermeasures against radiation-induced health impairments is the clear lack of controlled clinical studies, due to the relatively low number of radiation victims worldwide. Instead, established and accepted animal models, as well as the recommendations of national and international expert panels and committees, are the main sources of information. Therefore, the development of countermeasures requires comparison of data from many sources and accumulation of information consistent with the U. S. Food and Drug Administration's "Animal Rule." A new approach is the comparative analysis of human data from the SEARCH (System for Evaluation and Archiving of Radiation Accidents based on Case Histories) database and data from nonhuman primate (NHP) animal model studies. The SEARCH database contains 824 clinical cases from 81 radiation accidents in 19 countries. This exceptional collection of clinical data from accidentally radiation-exposed persons is analyzed regarding clinical signs and symptoms of radiation-induced health impairments. To analyze the time course of radiation syndromes, clinical parameters common to the SEARCH and NHP databases have to be assigned into comparable categories of clinical severity for each species. The goal is to establish a method for comparison of human and NHP data, validate the NHP data as a surrogate for human efficacy/clinical studies, and open a way for the extraction of diagnostic and treatment methods for humans after radiation exposure according to relevant regulations.

First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation.

OBJECTIVE: Hematopoietic syndrome (HS) is a clinical diagnosis assigned to people who present with ≥ 1 new-onset cytopenias in the setting of acute radiation exposure. The World Health Organization convened a panel of experts to evaluate the evidence and develop recommendations for medical countermeasures for the management of HS in a hypothetical scenario involving the hospitalization of 100 to 200 individuals exposed to radiation. The objective of this consultancy was to develop recommendations for treatment of the HS based upon the quality of evidence. METHODS: English-language articles were identified in MEDLINE and PubMed. Reference lists of retrieved articles were distributed to panel members before the meeting and updated during the meeting. Published case series and case reports of individuals with HS, published randomized controlled trials of relevant interventions used to treat nonirradiated individuals, reports of studies in irradiated animals, and prior recommendations of subject matter experts were selected. Studies were extracted using the Grading of Recommendations Assessment Development and Evaluation (GRADE) system. In cases in which data were limited or incomplete, a narrative review of the observations was made. No randomized controlled trials of medical countermeasures have been completed for individuals with radiation-associated HS. The use of GRADE analysis of countermeasures for injury to hematopoietic tissue was restricted by the lack of comparator groups in humans. Reliance on data generated in nonirradiated humans and experimental animals was necessary. RESULTS: Based upon GRADE analysis and narrative review, a strong recommendation was made for the administration of granulocyte colony-stimulating factor or granulocyte macrophage colony-stimulating factor and a weak recommendation was made for the use of erythropoiesis-stimulating agents or hematopoietic stem cell transplantation. CONCLUSIONS: Assessment of therapeutic interventions for HS in humans exposed to nontherapeutic radiation is difficult because of the limits of the evidence.

Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems.

OBJECTIVES: The World Health Organization convened a panel of experts to rank the evidence for medical countermeasures for management of acute radiation syndrome (ARS) in a hypothetical scenario involving the hospitalization of 100 to 200 victims. The goal of this panel was to achieve consensus on optimal management of ARS affecting nonhematopoietic organ systems based upon evidence in the published literature. METHODS: English-language articles were identified in MEDLINE and PubMed. Reference lists of retrieved articles were distributed to conferees in advance of and updated during the meeting. Published case series and case reports of ARS, publications of randomized controlled trials of relevant interventions used to treat nonirradiated individuals, reports of studies in irradiated animals, and prior recommendations of subject matter experts were selected. Studies were extracted using the Grading of Recommendations Assessment Development and Evaluation system. In cases in which data were limited or incomplete, a narrative review of the observations was made. RESULTS: No randomized controlled trials of medical countermeasures have been completed for individuals with ARS. Reports of countermeasures were often incompletely described, making it necessary to rely on data generated in nonirradiated humans and in experimental animals. A strong recommendation is made for the administration of a serotonin-receptor antagonist prophylactically when the suspected exposure is >2 Gy and topical steroids, antibiotics, and antihistamines for radiation burns, ulcers, or blisters; excision and grafting of radiation ulcers or necrosis with intractable pain; provision of supportive care to individuals with neurovascular syndrome; and administration of electrolyte replacement therapy and sedatives to individuals with significant burns, hypovolemia, and/or shock. A strong recommendation is made against the use of systemic steroids in the absence of a specific indication. A weak recommendation is made for the use of fluoroquinolones, bowel decontamination, loperamide, and enteral nutrition, and for selective oropharyngeal/digestive decontamination, blood glucose maintenance, and stress ulcer prophylaxis in critically ill patients. CONCLUSIONS: High-quality studies of therapeutic interventions in humans exposed to nontherapeutic radiation are not available, and because of ethical concerns regarding the conduct of controlled studies in humans, such studies are unlikely to emerge in the near future.

A Framework for Comparative Evaluation of Dosimetric Methods to Triage a Large Population Following a Radiological Event.

BACKGROUND: To prepare for a possible major radiation disaster involving large numbers of potentially exposed people, it is important to be able to rapidly and accurately triage people for treatment or not, factoring in the likely conditions and available resources. To date, planners have had to create guidelines for triage based on methods for estimating dose that are clinically available and which use evidence extrapolated from unrelated conditions. Current guidelines consequently focus on measuring clinical symptoms (e.g., time-to-vomiting), which may not be subject to the same verification of standard methods and validation processes required for governmental approval processes of new and modified procedures. Biodosimeters under development have not yet been formally approved for this use. Neither set of methods has been tested in settings involving large-scale populations at risk for exposure. OBJECTIVE: To propose a framework for comparative evaluation of methods for such triage and to evaluate biodosimetric methods that are currently recommended and new methods as they are developed. METHODS: We adapt the NIH model of scientific evaluations and sciences needed for effective translational research to apply to biodosimetry for triaging very large populations following a radiation event. We detail criteria for translating basic science about dosimetry into effective multi-stage triage of large populations and illustrate it by analyzing 3 current guidelines and 3 advanced methods for biodosimetry. CONCLUSIONS: This framework for evaluating dosimetry in large populations is a useful technique to compare the strengths and weaknesses of different dosimetry methods. It can help policy-makers and planners not only to compare the methods' strengths and weaknesses for their intended use but also to develop an integrated approach to maximize their effectiveness. It also reveals weaknesses in methods that would benefit from further research and evaluation.

Phase I pharmacokinetic and pharmacodynamic analysis of unconjugated soy isoflavones administered to individuals with cancer.

Preclinical studies suggest that the isoflavone genistein may have prostate cancer chemopreventive activity. Genistein has been shown to alter cellular levels of protein-tyrosine phosphorylation and is present at high levels in soy. This study was designed to measure the pharmacokinetic parameters of two different preparations of unconjugated soy isoflavones, PTI G-2535 and PTI G-4660 (which contain 43% and 90% genistein, respectively), in human subjects with cancer, to evaluate toxicity and obtain pilot data on in vivo effects on protein-tyrosine phosphorylation. Cohorts of four patients were given single doses of each preparation; each dose was separated by 1 week. Sequential cohorts received genistein at 2, 4, or 8 mg/kg orally. Pharmacokinetic sampling was performed after each dose, and tyrosine phosphorylation was measured in proteins extracted from peripheral blood mononuclear cells. One of 13 patients treated developed a treatment-related rash. No other toxicities were observed. Maximal plasma concentrations (C(max)) ranged between 4.3 and 16.3 micro M for total genistein and 0.066 and 0.17 micro M for free genistein. For PTI G-2535 and PTI G-4660, half-life was 15.03 and 22.41 h, respectively, and volume of distribution was 189.9 and 653.8 liters, respectively, and there was a trend toward higher area under the concentration curve for PTI G-2535 (P = 0.07 at the 8 mg/kg dose). Treatment-related increases in tyrosine phosphorylation were observed in peripheral blood mononuclear cells. Oral administration of soy isoflavones gives plasma concentrations of genistein that have been associated with antimetastatic activity in vitro.