Harnessing the Near-Peer Effect in Anatomy Education.

Benefits of near-peer teaching are well-documented, but its time requirements can be prohibitive. We integrated the near-peer effect into a clinical anatomy course with weekly student-developed handouts vetted by faculty to provide an element of near-peer teaching without the burden of extra time.

Local failure after radical radiotherapy of non-small cell lung cancer in relation to the planning FDG-PET/CT.

OBJECTIVES: Local recurrence (rec) in lung cancer is associated with poor survival. This study examined whether the pattern of failure is associated with the most PET avid volume in the planning-FDG-PET/CT scan (p-PET/CT). METHODS: 162 consecutive inoperable NSCLC patients (pts) receiving radiotherapy between January 2012 and April 2014 were reviewed. Radiotherapy was delivered in 2 Gy/fraction (5f/week) to a total dose of 60-66 Gy. Pts were followed with CT scans every third month. Patients with local rec as first event were analyzed. For the primary tumor (T) the overlap-fraction (OF) between 50% of SUVpeak on p-PET/CT and the volume of T-rec was calculated: OF = (SUVp50∩T-rec)/min(SUVp50, T-rec). Similarly for the GTV on the p-CT: OF = (GTV∩T-rec)/min(GTV, T-rec). OF was based on a rigid registration between p-PET/CT and rec-CT with PET guided delineation of T- rec. For lymph nodes (LN), the correlation between the location of treated-LN and the location of recurrence-LN was evaluated. RESULTS: 67 patients developed local rec. 51 pts had rec in T-site, 45 pts in LN-site. Due to anatomical changes, reliable registration between p-CT and rec-CT was only obtained in 26 pts with T-rec. The median OFSUVp50 was 52, 8% [range 26; 100%] and the median OFGTV was 80.5% [19.7; 100%]. Eleven pts had higher OFSUVp50 than OFGTV. LN-rec predominantly occurred in the station 2R (32%), 4R (46%), 7 (46%) and right hilum (36%). Pts with malignant LNs in station 4R or 7 on p-CT had a high risk of rec in these stations; 4R (55%) and 7 (83%). CONCLUSIONS: This study indicates that the most PET active volume on p-PET-CT is a driver for rec at T-site. LN-recurrences predominantly appear in station 2R, 4R, 7 and right hilum. Additional confirmatory studies regarding lymph node mapping and selective lymph node irradiation is needed.

The characterization of the Phlebotomus papatasi transcriptome.

As important vectors of human disease, phlebotomine sand flies are of global significance to human health, transmitting several emerging and re-emerging infectious diseases. The most devastating of the sand fly transmitted infections are the leishmaniases, causing significant mortality and morbidity in both the Old and New World. Here we present the first global transcriptome analysis of the Old World vector of cutaneous leishmaniasis, Phlebotomus papatasi (Scopoli) and compare this transcriptome to that of the New World vector of visceral leishmaniasis, Lutzomyia longipalpis. A normalized cDNA library was constructed using pooled mRNA from Phlebotomus papatasi larvae, pupae, adult males and females fed sugar, blood, or blood infected with Leishmania major. A total of 47 615 generated sequences was cleaned and assembled into 17 120 unique transcripts. Of the assembled sequences, 50% (8837 sequences) were classified using Gene Ontology (GO) terms. This collection of transcripts is comprehensive, as demonstrated by the high number of different GO categories. An in-depth analysis revealed 245 sequences with putative homology to proteins involved in blood and sugar digestion, immune response and peritrophic matrix formation. Twelve of the novel genes, including one trypsin, two peptidoglycan recognition proteins (PGRP) and nine chymotrypsins, have a higher expression level during larval stages. Two novel chymotrypsins and one novel PGRP are abundantly expressed upon blood feeding. This study will greatly improve the available genomic resources for P. papatasi and will provide essential information for annotation of the full genome.

The geography of demography: long-term demographic studies and species distribution models reveal a species border limited by adaptation.

Potential causes of species' geographic distribution limits fall into two broad classes: (1) limited adaptation across spatially variable environments and (2) limited opportunities to colonize unoccupied areas. Combining demographic studies, analyses of demographic responses to environmental variation, and species distribution models, we investigated the causes of range limits in a model system, the eastern border of the California annual plant Clarkia xantiana ssp. xantiana. Vital rates of 20 populations varied with growing season temperature and precipitation: fruit number and overwinter survival of 1-year-old seeds declined steeply, while current-year seed germination increased modestly along west-to-east gradients in decreasing temperature, decreasing mean precipitation, and increasing variation in precipitation. Long-term stochastic finite rate of increase, λ(s), exhibited a fourfold range and varied among geologic surface materials as well as with temperature and precipitation. Growth rate declined significantly toward the eastern border, falling below 1 in three of the five easternmost populations. Distribution models employing demographically important environmental variables predicted low habitat favorability beyond the eastern border. Models that filtered or weighted population presences by λ(s) predicted steeper eastward declines in favorability and assigned greater roles in setting the distribution to among-year variation in precipitation and to geologic surface material. These analyses reveal a species border likely set by limited adaptation to declining environmental quality.

Toward the framework and implementation for clearance of materials from regulated facilities.

The disposition of solid materials from nuclear facilities has been a subject of public debate for several decades. The primary concern has been the potential health effects resulting from exposure to residual radioactive materials to be released for unrestricted use. These debates have intensified in the last decade as many regulated facilities are seeking viable management decisions on the disposition of the large amounts of materials potentially containing very low levels of residual radioactivity. Such facilities include the nuclear weapons complex sites managed by the U.S. Department of Energy, commercial power plants licensed by the U.S. Nuclear Regulatory Commission (NRC), and other materials licensees regulated by the NRC or the Agreement States. Other facilities that generate radioactive material containing naturally occurring radioactive materials (NORM) or technologically enhanced NORM (TENORM) are also seeking to dispose of similar materials that may be radioactively contaminated. In contrast to the facilities operated by the DOE and the nuclear power plants licensed by the U.S. Nuclear Regulatory Commission, NORM and TENORM facilities are regulated by the individual states. Current federal laws and regulations do not specify criteria for releasing these materials that may contain residual radioactivity of either man-made or natural origin from regulatory controls. In fact, the current regulatory scheme offers no explicit provision to permit materials being released as "non-radioactive," including those that are essentially free of contamination. The only method used to date with limited success has been case-by-case evaluation and approval. In addition, there is a poorly defined and inconsistent regulatory framework for regulating NORM and TENORM. Some years ago, the International Atomic Energy Agency introduced the concept of clearance, that is, controlling releases of any such materials within the regulatory domain. This paper aims to clarify clearance as an important disposition option for solid materials, establish the framework and basis of release, and discuss resolutions regarding the implementation of such a disposition option.

Application of the Supreme Court's Daubert criteria in radiation litigation.

In 1993, the U.S. Supreme Court set forth the standard for determining the admissibility of expert scientific evidence in litigation. This standard is known as the Daubert criteria, named after the pertinent case, Daubert v. Merrell Dow Pharmaceuticals, Inc. The Daubert criteria require the courts to determine whether an expert's testimony reflects scientific knowledge, whether his/her findings are derived by the scientific method, and whether the work product is based on good science. The Daubert criteria are especially important in radiation litigation because issues involving radiation doses and effects are often complex and thus a jury will typically rely heavily on the analysis and opinions of experts. According to the Daubert criteria, scientific opinions must be based on a methodology that has a valid, testable hypothesis; has been subject to peer review; and is generally accepted in the scientific community. Additionally, the expert must be qualified to present opinions based on the methodology. Although the application of the Daubert criteria in radiation litigation is highly dependent on the specific court and judge presiding over the case, there have been recent high-profile cases in which application of the criteria has resulted in the dismissal of analysis and opinions offered by scientific experts. Reasons for the dismissals have included basic scientific errors such as failure of the expert to consider all possible explanations for an observed phenomenon, the selective use of data by the expert, and the failure to acknowledge and resolve inconsistencies between the expert's results and those of other investigators. This paper reviews the Daubert criteria as they apply to radiation litigation and provides examples of the application of the criteria from recent judgments involving the Three Mile Island and Hanford Downwinders cases.

Evaluation of uncertainties in estimates of fetal doses from 59Fe kinetic studies at Vanderbilt University.

In a 1997 paper, Stabin et al. published estimates of the fetal radiation doses for women who received oral administrations of 59Fe at Vanderbilt University in the 1940's. These authors concluded that there was "considerable uncertainty... in the amount of radioactive material administered to these subjects." In an effort to quantify this uncertainty, the underlying factors in the input data used in the Stabin et al. dose estimates have been examined in detail. Such factors include (a) an absence of detailed information on, and discrepancies in, the amounts of 59Fe reported to have been administered; (b) the probability that the radioactive iron included 55Fe as well as 59Fe; (c) uncertainties as to the period of time that elapsed between the administration of the radioiron and the taking of the maternal blood samples, and the accompanying impacts of radioactive decay; (d) possible losses of 59Fe in the procedures used in preparing the blood samples; and (e) questions as to the reported efficiency of the counting equipment. Our principal conclusion is that, due to the significant uncertainties and the lack of key information, it is not possible to estimate the doses accurately. An ancillary conclusion, however, is that the doses were probably significantly higher than previously estimated. This latter possibility should be carefully considered by any investigators who subsequently seek to use these estimates to quantify the relationship between the doses to the fetus and the resulting health effects.

Heterotopic ossification and peripheral nerve entrapment: early diagnosis and excision.

Heterotopic ossification can occur in neurologic disorders, burns, musculoskeletal trauma, and metabolic disorders. In addition to producing the complications of contracture, skin breakdown, and pain, it can cause peripheral nerve entrapment. Nerve entrapment due to heterotopic ossification may be misdiagnosed, and it is difficult to evaluate and treat without recurrence. Computed tomography is especially useful in localization before surgical release of the entrapped nerve. Resection of heterotopic ossification can be successful using disodium etidronate to decrease the risk of recurrence, and resection can improve range of motion and nerve function. Two case studies of nerve entrapment due to heterotopic ossification are presented with the results of computed tomography localization, successful resection, and long-term follow-up. Clinicians should be aware of this complication and the potential for rapid nerve injury. If heterotopic ossification is causing clinically significant peripheral nerve entrapment, early surgical treatment may be indicated, and may be successful.

Optimization of filtration for reduction of lung dose from Rn decay products: Part I--Theoretical.

A theoretical model was developed for the optimization of filter characteristics that would minimize the dose from the inhalation of Rn decay products. Modified forms of the Jacobi-Porstendorfer room model and the Jacobi-Eisfeld lung dose model were chosen for use in the mathematical simulation. Optimized parameters of the filter were the thickness, solidity, and fiber diameter. For purposes of the calculations, the room dimensions, air exchange rate, particle-size distribution and concentration, and the Rn concentration were specified. The resulting computer-aided optimal design was a thin filter (the minimum thickness used in the computer model was 0.1 mm) having low solidity (the minimum solidity used was 0.5%) and large diameter fibers (the maximum diameter used was 100 microns). The simulation implies that a significant reduction in the dose rate can be achieved using a well-designed recirculating filter system. The theoretical model, using the assumption of ideal mixing, predicts an 80% reduction in the dose rate, although inherent in this assumption is the movement of 230 room volumes per hour through the fan.

Optimization of filtration for the reduction of lung dose from Rn decay products: Part II--Experimental.

Research was performed to determine the validity of a model developed to theoretically predict the optimal characteristics of a recirculating filter system for minimizing the lung dose to a person breathing airborne Rn progeny. Four designs, each with different filter thicknesses, solidities, and fiber diameters, were tested to evaluate the accuracy of the model over a range of parameters. Increasing thicknesses were then tested for the most effective filter design to provide a more definitive comparison of experimental data and model predictions for this key parameter. The experimental data supported the conclusion that the most effective design was a thin filter of low solidity composed of coarse fibers. Although the maximum reduction in the dose-equivalent rate observed in these experiments was 50%, this was largely due to constraints on the experimental arrangements. With properly constructed filter units, much better removal efficiencies can undoubtedly be achieved.

Upper extremity venous thrombosis diagnosed by duplex scanning.

The incidence of axillary-subclavian venous thrombosis continues to rise, while reports of noninvasive methods to diagnose this condition have been sparse. A review of the records of 693 consecutive upper extremity duplex scans was performed, and a diagnosis of acute venous thrombosis was made in 123 of these patients. Of these, 85 involved the axillary or subclavian vein. Use of a central venous catheter was the most common risk factor for axillary-subclavian venous thrombosis. Within this group, 8% had a pulmonary embolism, of which 25% were fatal. Follow-up of patients with axillary-subclavian venous thrombosis at a mean of 2 years revealed that 49% of these patients had died. Of the remaining patients, more than one third had evidence of the post-thrombotic syndrome. Duplex scanning of the venous system provides a safe, reliable, and repeatable method of evaluating and following patients with suspected venous thrombosis of the upper extremity.

Radiological health effects models for nuclear power plant accident consequence analysis.

Improved health effects models have been developed for assessing the early effects, late somatic effects and genetic effects that might result from low-LET radiation exposures to populations following a major accident in a nuclear power plant. All the models have been developed in such a way that the dynamics of population risks can be analyzed. Estimates of life years lost and the duration of illnesses were generated and a framework recommended for summarizing health impacts. Uncertainty is addressed by providing models for upper, central and lower estimates of most effects. The models are believed to be a significant improvement over the models used in the U.S. Nuclear Regulatory Commission's Reactor Safety Study, and they can easily be modified to reflect advances in scientific understanding of the health effects of ionizing radiation.

Crohn's disease beginning during pregnancy.

I have reported the 11th case of Crohn's disease initially symptomatic during pregnancy. The complication rate is very high in this rare clinical syndrome. Of the ten previously described patients, five had surgical intervention during pregnancy. Seven of twelve infants and two of the 11 patients ultimately died. The prognosis is probably no better now than it was when the entity was initially described 40 years ago.