Radiation injury and the surgeon

Radiological and Nuclear Terrorism: The Oncologic Emergency Response

Public concern about the possibility of terrorism involving radiological materials has grown rapidly since the September 11, 2001 terrorist attacks on New York City, the Pentagon, and Pennsylvania. Such concern is driven by the widespread availability of radiological materials and the intentions of malfeasants and organizations around the world to do harm to others. In contrast to nuclear materials, radiological materials are ubiquitous and are found in most cities throughout the country at academic institutions, hospitals, and many businesses and industrial settings. In contrast, nuclear materials are difficult to access because of their rarity and the security of the settings in which they are found. A radiological or nuclear incident of any kind will require prompt assessment of the location and nature of the incident, activation of mass casualty response systems, followed by immediate consultation of hematology, health and medical physics, and nuclear medicine personnel. Radiation-induced injuries and illnesses are typically delayed. Successful assessment and management of individuals with acute radiation syndrome (ARS), including the hematopoietic subsyndrome (HS), is required to support management of injuries resulting from a high radiation dose, including injuries to the gastrointestinal and neurovascular systems. Administration of cytokines within 24 h of exposure shortens the period of granulocytopenia and is strongly recommended by subject matter experts in the management of the HS. Hematopoietic stem cell transplantation after failure of a 2–3 week trial of cytokines has been clearly documented and is weakly recommended in selected individuals with the HS. Administration of prophylactic and therapeutic broad-spectrum antimicrobials (including antibacterial, antiviral, and antifungal agents) is recommended and should be guided by recommendations of the Infectious Diseases Society of America for management of febrile neutropenia. This article provides an overview for clinicians who are called upon in a radiological and/or nuclear incident to manage individuals with ARS and other radiation-related illnesses.

Radiation Injury Presenting to the Emergency Department: A Case Report

Radiation injuries are closer to home than expected as radioactive sources are common in daily life. Our case study illustrates a case of radiation burns to the hand which presented about two weeks later to the emergency department after accidental exposure to an industrial radiation source. A 45-year old Chinese man presented 17 days later after being exposed accidentally to iridium-192 source at 43 curies. He subsequently suffered burns that required multiple operations to treat. The diagnosis of patients who present early after exposure with no clinical signs will likely pose a challenge for the emergency medicine clinician as radiation burns take time to manifest and may present days to weeks after radiation exposure.

Stem cell therapy: a novel & futuristic treatment modality for disaster injuries

Stem cell therapy hold the potential to meet the demand for transplant cells/tissues needed for treating damages resulting from both natural and man-made disasters. Pluripotency makes embryonic stem cells and induced pluripotent stem cells ideal for use, but their teratogenic character is a major hindrance. Therapeutic benefits of bone marrow transplantation are well known but characterizing the potentialities of haematopoietic and mesenchymal cells is essential. Haematopoietic stem cells (HSCs) have been used for treating both haematopoietic and non-haematopoietic disorders. Ease of isolation, in vitro expansion, and hypoimmunogenecity have brought mesenchymal stem cells (MSCs) into limelight. Though differentiation of MSCs into tissue-specific cells has been reported, differentiation-independent mechanisms seem to play a more significant role in tissue repair which need to be addressed further. The safety and feasibility of MSCs have been demonstrated in clinical trials, and their use in combination with HSC for radiation injury treatment seems to have extended benefit. Therefore, using stem cells for treatment of disaster injuries along with the conventional medical practice would likely accelerate the repair process and improve the quality of life of the victim.

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.

Interaction between cytotoxic effects of gamma-radiation and folate deficiency in relation to choline reserves

The search for non-toxic radio-protective drugs has yielded many potential agents but most of these compounds have certain amount of toxicity. Recent studies have indicated that bio-molecules such as folate and choline might be of radio-protective value as they are, within broad dose ranges, non-toxic to humans and experimental animals. The objective of the present study was to investigate choline dependent adaptive response to potential synergistic cytotoxic effect of folate deficiency and gamma-radiation. Male Swiss mice maintained on folate sufficient diet (FSD) and folate free diet (FFD) based on AIN-93M formula, were subjected to 1-4Gy total body gamma-irradiation. To investigate liver DNA damage, apurinic/apyrimidinic sites (AP sites) were quantified. A significant increase in liver DNA AP sites with concomitant depletion of liver choline reserves was observed when gamma-radiation was combined with folate deficiency. Further work in this direction suggested that cytotoxic interaction between folate deficiency and gamma radiation might induce utilization of choline and choline containing moieties by modifying levels of key regulatory enzymes dihydrofolate reductase (DHFR) and choline oxidase (ChoOx). Another major finding of these studies is that significant liver damage at higher doses of radiation (3-4Gy), might release considerable amounts of choline reserves to serum. In conclusion, a plausible interpretation of the present studies is that folate deprivation and gamma-radiation interact to mobilize additional choline reserves of hepatic tissue, for redistribution to other organs, which could not be utilized by folate deficiency alone. Present results clearly indicated a distinct choline pool in liver and kidney tissues that could be utilized by folate deficient animals only under radiation stress conditions.

Radiation injury and the hand surgeon

The human hand has been affected by ionizing radiation accidents than any other organ. Hand surgeons should understand the pathophysiology and appropriate management of various types of radiation injury. This article outlines the history and epidemiology of ionizing radiation injury to the hand, basic aspects of radiobiology, and principles of management for injury resulting from fluoroscopy, nuclear accidents or weapons, and other sources.