Radiation biodosimetry: applications for spaceflight

The multiparametric dosimetry system that we are developing for medical radiological defense applications could be adapted for spaceflight environments. The system complements the internationally accepted personnel dosimeters and cytogenetic analysis of chromosome aberrations, considered the best means of documenting radiation doses for health records. Our system consists of a portable hematology analyzer, molecular biodosimetry using nucleic acid and antigen-based diagnostic equipment, and a dose assessment management software application. A dry-capillary tube reagent-based centrifuge blood cell counter (QBC Autoread Plus, Becton [correction of Beckon] Dickinson Bioscience) measures peripheral blood lymphocytes and monocytes, which could determine radiation dose based on the kinetics of blood cell depletion. Molecular biomarkers for ionizing radiation exposure (gene expression changes, blood proteins) can be measured in real time using such diagnostic detection technologies as miniaturized nucleic acid sequences and antigen-based biosensors, but they require validation of dose-dependent targets and development of optimized protocols and analysis systems. The Biodosimetry Assessment Tool, a software application, calculates radiation dose based on a patient's physical signs and symptoms and blood cell count analysis. It also annotates location of personnel dosimeters, displays a summary of a patient's dosimetric information to healthcare professionals, and archives the data for further use. These radiation assessment diagnostic technologies can have dual-use applications supporting general medical-related care.

Clonal relationships in a shelter-associated outbreak of drug-resistant tuberculosis: 1983-1997

SETTING

An outbreak of tuberculosis caused by Mycobacterium tuberculosis resistant to isoniazid and streptomycin (HS-resistant) was documented in Boston's homeless population in 1984. Isolate relatedness was confirmed at the time by phage typing. In the late 1990s, cases of HS-resistant tuberculosis in the homeless were also documented, confirmed by RFLP typing using IS6110. None of the phage typed isolates from the 1980s were viable for performing RFLP analysis. We attempted to determine, using mixed-linker PCR (M-L PCR) finger-printing, whether or not these cases were all due to the same strain of M. tuberculosis.

DESIGN

Isolates from 10 HS-resistant patients-four non-viable isolates from the 1980s and six viable isolates from 1996-1997-were sent to the Centers for Disease Control and Prevention for M-L PCR fingerprinting. These results were combined with record reviews of older cases and an ongoing epidemiologic investigation.

RESULTS

Eight of 10 of the isolates were clonal, and the other two were strongly suspected matches. Epidemiologic investigation determined that transmission continued to occur after the initial outbreak in 1984-1985, and that a streptomycin-monoresistant variant of the strain was also circulating.

CONCLUSION

M-L PCR fingerprinting combined with epidemiology was able to document links between cases across 15 years.

Observation of radiation-specific damage in human cells exposed to depleted uranium: dicentric frequency and neoplastic transformation as endpoints

Depleted uranium (DU) is a dense heavy metal used primarily in military applications. Published data from our laboratory have demonstrated that DU exposure in vitro to immortalised human osteoblast cells (HOS) is both neoplastically transforming and genotoxic. DU possesses both a radiological (alpha-particle) and chemical (metal) component. Since DU has a low specific activity in comparison to natural uranium, it is not considered to be a significant radiological hazard. The potential contribution of radiation to DU-induced biological effects is unknown and the involvement of radiation in DU-induced biological effects could have significant implications for current risk estimates for internalised DU exposure. Two approaches were used to address this question. The frequency of dicentrics was measured in HOS cells following DU exposure in vitro. Data demonstrated that DU exposure (50 microM, 24 h) induced a significant elevation in dicentric frequency in vitro in contrast to incubation with the heavy metals, nickel and tungsten which did not increase dicentric frequency above background levels. Using the same concentration (50 microM) of three uranyl nitrate compounds that have different uranium isotopic concentrations and therefore, different specific activities, the effect on neoplastic transformation in vitro was examined. HOS cells were exposed to one of three-uranyl nitrate compounds (238U-uranyl nitrate, specific activity 0.33 microCi.g-1; DU-uranyl nitrate, specific activity 0.44 microCi.g-1; and 235U-uranyl nitrate, specific activity 2.2 microCi.g-1) delivered at a concentration of 50 microM for 24 h. Results showed, at equal uranium concentration, there was a specific activity dependent increase in neoplastic transformation frequency. Taken together these data suggest that radiation can play a role in DU-induced biological effects in vitro.

Proto-oncogene expression: a predictive assay for radiation biodosimetry applications

Using a model system of in vitro human peripheral blood lymphocytes, the effect of low-dose (0.25 to 1.50 Gy) 250-kVp X ray radiation (1 Gy.min-1) on the expression of several proto-oncogenes was examined (c-Haras, c-src, c-met, c-jun, c-fos, and c-myc) and beta-actin from 0.25 to 17 h post-radiation. RNA was extracted from cells harvested at various times after exposure and examined for levels of particular mRNAs by northern blot hybridisation. A progressive time- and dose-dependent increase in mRNA levels was observed for c-Haras mRNA, while the other proto-oncogenes (c-src, c-met, c-fos, c-jun and c-myc) examined were variable during the same time period. beta-actin levels were initially decreased but at 17 h post-radiation had returned to control levels. A comparison of the rate of c-Haras transcription at 5 and 17 h post-irradiation revealed that c-Haras transcription was higher at 5 h than at 17 h. These findings suggest that the level of specific proto-oncogene expression, particularly c-Haras, may be useful early diagnostic molecular biomarkers for biodosimetry applications. The use of real-time PCR technologies to quantify gene expression changes will also be discussed.

Biological effects of embedded depleted uranium (DU): summary of armed forces radiobiology research institute research

The Persian Gulf War resulted in injuries of US Coalition personnel by fragments of depleted uranium (DU). Fragments not immediately threatening the health of the individuals were allowed to remain in place, based on long-standing treatment protocols designed for other kinds of metal shrapnel injuries. However, questions were soon raised as to whether this approach is appropriate for a metal with the unique radiological and toxicological properties of DU. The Armed Forces Radiobiology Research Institute (AFRRI) is investigating health effects of embedded fragments of DU to determine whether current surgical fragment removal policies remain appropriate for this metal. These studies employ rodents implanted with DU pellets as well as cultured human cells exposed to DU compounds. Results indicate uranium from implanted DU fragments distributed to tissues far-removed from implantation sites, including bone, kidney, muscle, and liver. Despite levels of uranium in the kidney that were nephrotoxic after acute exposure, no histological or functional kidney toxicity was observed. However, results suggest the need for further studies of long-term health impact, since DU was found to be mutagenic, and it transformed human osteoblast cells to a tumorigenic phenotype. It also altered neurophysiological parameters in rat hippocampus, crossed the placental barrier, and entered fetal tissue. This report summarizes AFRRI's depleted uranium research to date.

Impact of the therapist-child dyad on children's pain and coping during medical procedures

This study examined the effects of physical therapists' behaviors on the levels of distress and coping of 32 children (19 males, 11 females; age range 2.6 to 9.1 years) during a painful medical procedure. This is the second study to assess children throughout rehabilitation following selective posterior rhizotomy and the first to assess the impact of physical therapists' behaviors. Results of the Child-Adult Medical Procedure Interaction Scale-Revised confirmed the hypotheses that: (1) children exhibit more coping behaviors and fewer distress behaviors over time, and (2) positive relationships exist between coping-promoting behaviors in physical therapists and coping in children, and distress-promoting behaviors in physical therapists and distress in children. Prompts for children to use a coping strategy, reassuring comments, and non-procedural talk by therapists explained 67% of the variance in children's coping. Criticism, reassurance, checking child's status, praise, and empathic statements by therapists explained 65% of the variance in children's distress. Older children and children with higher IQ scores exhibited more coping behaviors.

Radiation exposure assessment using cytological and molecular biomarkers

Chromosome aberration analysis is the conventional means of assessing radiation exposure. The Armed Forces Radiobiology Research Institute recently established an alternative method to measure radiation-induced chromosome aberrations in interphase cells. The method uses commercially available chemical agents to induce premature chromosome condensation in resting' G0 human peripheral blood lymphocytes. Then specific whole-chromosome DNA probes are used with fluorescence in situ hybridisation to detect aberrant cells rapidly over a broad dose range. In new research, the real-time fluorogenic 5'-nuclease, or TaqMan, polymerase chain reaction assay is being used to identify radiation-responsive molecular biomarkers, including gene expression targets and DNA mutations. The goal is to establish rapid, precise, high-throughput assay systems that are practical in a variety of radiation exposure scenarios. The new methodologies that have a number of other applications, together with diagnostic software now in development, could improve the United States military's emergency response capability and medical readiness.

Suppression of depleted uranium-induced neoplastic transformation of human cells by the phenyl fatty acid, phenyl acetate: chemoprevention by targeting the p21RAS protein pathway

Depleted uranium is a dense heavy metal used primarily in military applications. Published data from our laboratory have demonstrated that exposure to depleted uranium in vitro can transform immortalized human osteoblast (HOS) cells to the tumorigenic phenotype (associated with aberrant RAS oncogene expression and tumor suppressor protein production). Since depleted uranium is used in military applications, it would therefore be beneficial to identify and test potential antitumor-promoting agents. Chemopreventive interventions that target deregulated signal transduction pathways may be effective strategies to prevent carcinogenesis. Since the RAS protein plays a key role in signal transduction, disruption of its signaling pathway may be particularly effective. The phenyl fatty acid, phenyl acetate, a differentiation inducer that affects post-translational processing of RAS, was tested for its ability to prevent depleted uranium-induced neoplastic transformation using HOS cells. After a 24-h exposure to insoluble depleted uranium-uranium dioxide (1 mg/ml), cells were incubated for 1 day to 6 weeks with 2.5 mM phenyl acetate. Treatment with depleted uranium resulted in transformation to the tumorigenic phenotype. In contrast, HOS cells exposed to depleted uranium and then treated with phenyl acetate did not exhibit transformation to the tumorigenic phenotype. These data suggest that depleted uranium-induced neoplastic transformation in vitro can be prevented by targeting the RAS protein.

Neoplastic transformation of human osteoblast cells to the tumorigenic phenotype by heavy metal-tungsten alloy particles: induction of genotoxic effects

Heavy metal-tungsten alloys (HMTAs) are dense heavy metal composite materials used primarily in military applications. HMTAs are composed of a mixture of tungsten (91-93%), nickel (3-5%) and either cobalt (2-4%) or iron (2-4%) particles. Like the heavy metal depleted uranium (DU), the use of HMTAs in military munitions could result in their internalization in humans. Limited data exist, however, regarding the long-term health effects of internalized HMTAs in humans. We used an immortalized, non-tumorigenic, human osteoblast-like cell line (HOS) to study the tumorigenic transforming potential of reconstituted mixtures of tungsten, nickel and cobalt (rWNiCo) and tungsten, nickel and iron (rWNiFe). We report the ability of rWNiCo and rWNiFe to transform immortalized HOS cells to the tumorigenic phenotype. These HMTA transformants are characterized by anchorage-independent growth, tumor formation in nude mice and high level expression of the K-ras oncogene. Cellular exposure to rWNiCo and rWNiFe resulted in 8.90 +/- 0.93- and 9.50 +/- 0.91-fold increases in transformation frequency, respectively, compared with the frequency in untreated cells. In comparison, an equivalent dose of crystalline NiS resulted in a 7.7 +/- 0.73-fold increase in transformation frequency. The inert metal tantalum oxide did not enhance HOS transformation frequency above untreated levels. The mechanism by which rWNiCo and rWNiFe induce cell transformation in vitro appears to involve, at least partially, direct damage to the genetic material, manifested as increased DNA breakage or chromosomal aberrations (i.e. micronuclei). This is the first report showing that HMTA mixtures of W, Ni and Co or Fe cause human cell transformation to the neoplastic phenotype. While additional studies are needed to determine if protracted HMTA exposure produces tumors in vivo, the implication from these in vitro results is that the risk of cancer induction from internalized HMTAs exposure may be comparable with the risk from other biologically reactive and insoluble carcinogenic heavy metal compounds (e.g. nickel subsulfide and nickel oxide).

Assessment training and team functioning for treating children with disabilities

OBJECTIVE

To investigate differences in team functioning before and after assessment training.

DESIGN

Before-after trial.

SETTING

Outpatient rehabilitation and education program in a university medical center-based rehabilitation institute.

PARTICIPANTS

A population-based sample of 19 rehabilitation and education specialists.

INTERVENTION

Baseline measures were taken during four meetings using the multidisciplinary team approach. Training in a global measure of child development ensued and staff administered the test to children in their care. Test results were then used during four transdisciplinary team meetings.

OUTCOME MEASURES

Behavioral ratings of team participation (Transdisciplinary Team Rating Scale), self-report instruments of team development (Team Assessment Questionnaire), treatment planning and goal development (Staff Perception Questionnaire).

RESULTS

Results of t tests confirmed two of three hypotheses. There was more team member participation during transdisciplinary meetings than during multidisciplinary meetings (p = .003) and staff members' perceptions of the efficacy of treatment planning and implementation of goals significantly favored the transdisciplinary model (p < .001). No significant difference was found in team development (p = .254).

CONCLUSION

This study provides evidence for the value of training in an assessment tool that requires the use of a common, functional language that is comprehensible to all staff members and promotes a transdisciplinary approach to team work.

Spontaneous cell sorting of fibroblasts and keratinocytes creates an organotypic human skin equivalent

We show that an inherent ability of two distinct cell types, keratinocytes and fibroblasts, can be relied upon to accurately reconstitute full-thickness human skin including the dermal-epidermal junction by a cell-sorting mechanism. A cell slurry containing both cell types added to silicone chambers implanted on the backs of severe combined immunodeficient mice sorts out to reconstitute a clearly defined dermis and stratified epidermis within 2 wk, forming a cell-sorted skin equivalent. Immunostaining of the cell-sorted skin equivalent with human cell markers showed patterns similar to those of normal full-thickness skin. We compared the cell-sorted skin equivalent model with a composite skin model also made on severe combined immunodeficient mice. The composite grafts were constructed from partially differentiated keratinocyte sheets placed on top of a dermal equivalent constructed of devitalized dermis. Electron microscopy revealed that both models formed ample numbers of normal appearing hemidesmosomes. The cell-sorted skin equivalent model, however, had greater numbers of keratin intermediate filaments within the basal keratinocytes that connected to hemidesmosomes, and on the dermal side both collagen filaments and anchoring fibril connections to the lamina densa were more numerous compared with the composite model. Our results may provide some insight into why, in clinical applications for treating burns and other wounds, composite grafts may exhibit surface instability and blistering for up to a year following grafting, and suggest the possible usefulness of the cell-sorted skin equivalent in future grafting applications.

Stress and family satisfaction in parents of children with facial port-wine stains

A cross-sectional survey was employed to assess parenting stress, family satisfaction, and parental concerns and to determine predictors of stress in parents of children with port-wine stains (PWSs). The participants were 46 parents of 24 children receiving treatment with pulsed dye laser photocoagulation for facial PWS at an outpatient dermatology clinic based at a university medical center. Outcome measures used were self-report instruments assessing psychosocial adjustment (Parenting Stress Index, Family Satisfaction Scale, and Parental Concerns Questionnaire). As a group, parents scored in the average range on the stress and family satisfaction measures when compared with a normative sample; five parents (11%) scored in the clinical range for stress. Forty-nine percent of the variance in parenting stress was accounted for by four variables: the child's age (beta = 0.34; p = 0.031), the parents' degree of family satisfaction (beta = -0.27; p = 0.077), the level of parental concern regarding the child's facial PWS (beta = 0.45; p = 0.005), and the parents' satisfaction with staff communication (beta = -0. 51; p = 0.002). The data suggest that while, as a group, parents of children with a facial PWS report to be in the average range for psychological stress, some do not fare as well as others. Factors associated with lower stress include younger children, more family cohesion and adaptation, fewer parental concerns, and greater satisfaction with parent-staff communication. The potential for the development of medical complications and psychological problems over time suggests the need for treatment of the PWS at an early age. Health care providers should be prepared to screen for clinical levels of distress and to refer parents for psychological intervention when needed.

Urinary and serum mutagenicity studies with rats implanted with depleted uranium or tantalum pellets

During the 1991 Persian Gulf War several US military personnel were wounded by shrapnel fragments consisting of depleted uranium. These fragments were treated as conventional shrapnel and were not surgically removed to spare excessive tissue damage. Uranium bioassays conducted over a year after the initial uranium injury indicated a significant increase in urine uranium levels above natural background levels. The potential mutagenic effects of depleted uranium are unknown. To assess the potential mutagenic effects of long-term exposure to internalized depleted uranium, Sprague-Dawley rats were implanted with depleted uranium and their urine and serum were evaluated for mutagenic potential at various times after pellet implantation using the Ames Salmonella reversion assay. Tantalum, an inert metal widely used in prosthetic devices was used for comparison. Enhancement of mutagenic activity in Salmonella typhimurium strain TA98 and the Ames II mixed strains (TA7001-7006) was observed in urine samples from animals implanted with depleted uranium pellets. In contrast, urine samples from animals implanted with tantalum did not show a significant enhancement of mutagenic activity in these strains. In depleted uranium-implanted animals, urine mutagenicity increased in a dose- and time-dependent manner demonstrating a strong positive correlation with urine uranium levels (r = 0.995, P < 0.001). There was no mutagenic enhancement of any bacterial strain detected in the sera of animals implanted with either depleted uranium or tantalum pellets. The results suggest that uranium content in the urine is correlated with urine mutagenicity and that urinary mutagenicity might be used as a biomarker to detect exposure to internalized uranium.

Transformation of human osteoblast cells to the tumorigenic phenotype by depleted uranium-uranyl chloride

Depleted uranium (DU) is a dense heavy metal used primarily in military applications. Although the health effects of occupational uranium exposure are well known, limited data exist regarding the long-term health effects of internalized DU in humans. We established an in vitro cellular model to study DU exposure. Microdosimetric assessment, determined using a Monte Carlo computer simulation based on measured intracellular and extracellular uranium levels, showed that few (0.0014%) cell nuclei were hit by alpha particles. We report the ability of DU-uranyl chloride to transform immortalized human osteoblastic cells (HOS) to the tumorigenic phenotype. DU-uranyl chloride-transformants are characterized by anchorage-independent growth, tumor formation in nude mice, expression of high levels of the k-ras oncogene, reduced production of the Rb tumor-suppressor protein, and elevated levels of sister chromatid exchanges per cell. DU-uranyl chloride treatment resulted in a 9.6 (+/- 2.8)-fold increase in transformation frequency compared to untreated cells. In comparison, nickel sulfate resulted in a 7.1 (+/- 2.1)-fold increase in transformation frequency. This is the first report showing that a DU compound caused human cell transformation to the neoplastic phenotype. Although additional studies are needed to determine if protracted DU exposure produces tumors in vivo, the implication from these in vitro results is that the risk of cancer induction from internalized DU exposure may be comparable to other biologically reactive and carcinogenic heavy-metal compounds (e.g., nickel).

Team approaches to treating children with disabilities: a comparison

OBJECTIVE

To investigate differences in team functioning between the multidisciplinary and transdisciplinary models when treating children with disabilities.

DESIGN

A crossover trial.

SETTING

An outpatient educational and rehabilitation program in a rehabilitation institute based at a university medical center.

PARTICIPANTS

A population-based sample of 19 rehabilitation specialists and educators.

INTERVENTION

Participants attended four team meetings using the multidisciplinary approach and then attended four team meetings using the transdisciplinary approach.

OUTCOME MEASURES

Behavioral ratings of team participation (Transdisciplinary Team Rating Scale) and self-report instruments of team development (Team Assessment Questionnaire) and treatment planning and goal development (Staff Perception Questionnaire).

RESULTS

Results of t tests confirmed the hypothesis that there was more team member participation during transdisciplinary meetings than during multidisciplinary meetings (p=.027). There were no differences in levels of team development (p=.329); however, staff members favored the transdisciplinary model for treatment planning and goal development (p < .001).

CONCLUSION

This study provides evidence of the effectiveness of the transdisciplinary model. Further research is now needed to investigate outcome variables such as rate of success in attaining treatment goals when using this model.

Pain, anxiety, and cooperativeness in children with cerebral palsy after rhizotomy: changes throughout rehabilitation

Assessed pain, anxiety, physical functioning, and cooperativeness in 32 children with spastic cerebral palsy. This is the first study to assess children throughout rehabilitation following selective posterior rhizotomy. Results of the Observational Scale of Behavioral Distress and observer Likert ratings confirmed the hypothesis that children's pain and anxiety decrease over time. Children's physical functioning and cooperativeness improve over time. No significant correlation was found between pain and changes in physical functioning. Cognitive impairment, parental involvement, and children's pain behaviors explained 77% and 56% of the variance in two forms of cooperativeness. Research and clinical implications are discussed, and special considerations regarding pain assessment and management in this population are addressed.

Active management of labor: does it make a difference?

OBJECTIVE

Our goal was to evaluate whether active management of labor lowers cesarean section rates, shortens the length of labor, and overcomes any negative effects of epidural analgesia on nulliparous labor.

STUDY DESIGN

We randomly assigned 405 low-risk term nulliparous patients to either an active management of labor (n = 200) or our usual care control protocol (n = 205). Patients who were undergoing active management of labor were diagnosed as being in labor on the basis of having painful palpable contractions accompanied by 80% cervical effacement, underwent early amniotomy, and were treated with high-dose oxytocin for failure to progress adequately in labor.

RESULTS

The cesarean section rate in the active management of labor group was lower than that of controls but not significantly so (active management, 7.5%; controls, 11.7%; p = 0.36). The length of labor in the active management group was shortened by 1.7 hours (from 11.4 to 9.7 hours, p = 0.001). Fifty-five percent of patients received epidural analgesics; a reduction in length of labor persisted despite the use of epidural analgesics (active management 11.2 hours vs control 13.3 hours, p = 0.001). A significantly greater proportion of active management patients were delivered by 12 hours compared with controls (75% vs 58%, p = 0.01); this difference also persisted despite the use of epidural analgesics (66% vs 51%, p = 0.03).

CONCLUSIONS

Patients undergoing active management had shortened labors and were more likely to be delivered within 12 hours, differences that persisted despite the use of epidural analgesics. There was a trend toward a reduced rate of cesarean section.

Modulation of radiation response of human tumour cells by the differentiation inducers, phenylacetate and phenylbutyrate

The aromatic fatty acids phenylacetate (PA) and phenylbutyrate (PB) are novel antitumour agents currently under clinical evaluation. Their ability to induce tumour differentiation in laboratory models and their low clinical toxicity profile makes them promising candidates for combination with conventional therapies. In the present studies, we characterized the interactions between these aromatic fatty acids and radiation, using as a model cell lines derived from cancers of the prostate, breast, brain and colon. Analysis of the radiation response of the tumour lines using the linear-quadratic model, demonstrated that cellular exposure to pharmacological, non-toxic concentrations of either PA or PB resulted in time-dependent and contrasting changes in radiation response. While drug pretreatment for 24 h reduced radiation sensitivity (significant alterations in both alpha and beta parameters), pre treatment for 72 h significantly increased radiosensitivity (significant alterations in alpha and beta parameters). In replicating tumour cells, these changes were accompanied by a gradual G1-phase arrest. Cytostasis alone, however, could not explain radiosensitization, as similar alterations in radiation response were documented also in non-cycling cells. Modulation of tumour radiobiology by PA and PB was tightly correlated with early rise followed by decline in intracellular glutathione levels and the activity of antioxidant enzymes such as catalase, superoxide dismutase, glutathione reductase, glutathione peroxidase and glutathione S-transferase. Although in vitro findings identify the aromatic fatty acids PA and PB as a new class of non-toxic modulators of radiation response, the antagonistic effect of these compounds on radiation response needs further examination. Our data strongly suggest that for PA or PB to have a role in clinical radiotherapy, appropriate scheduling of combination therapies must take into account their time-dependent effects in order to achieve clinical radiosensitization.

To everything turn, turn, turn.... An overview of continuous lateral rotational therapy

Continuous lateral rotational therapy can be a significant adjunct in the care of the critically ill patient. CLRT has a great impact on both patient outcomes as well as cost containment in the care of the critically ill. These systems should be used with clear guidelines to determine when CLRT is indicated, its therapeutic benefit, and when to discontinue the therapy. Much research is needed to validate efficacy of particular systems, cost-effectiveness, and necessary frequency and degree of rotation to attain optimal clinical benefits.