Quantifying Older Black Americans' Exposure to Structural Racial Discrimination: How Can We Measure the Water In Which We Swim?

The USA was built on legalized racism that started with enslavement and continues in the form of structural racial discrimination. This discrimination is difficult to measure because its many manifestations are hard to observe and dynamic. A useful tool would measure across settings, institutions, time periods in a person's life and the country's history. The purpose of this study was to design a measure of structural racial discrimination that meets those criteria and can be used in large national datasets. To do this, we started with an exploratory mixed-methods instrument design, including qualitative interviews with 15 older Black adults and focus groups with 38 discrimination researchers and other key stakeholders. We then identified 27 indicators of structural racial discrimination across nine theorized discrimination contexts. We matched these with historical administrative data sets to develop an instrument that could quantify older Black Americans' exposure to structural racial discrimination across contexts, the life course, and geographies. These can be mapped to the life course of structural discrimination based on the home addresses of those surveyed. Linking these to available indicators is a promising approach. It is a low burden for participants and enables increasingly multifaceted and focused measurement as more national datasets become available. A flexible, feasible comprehensive measure of structural discrimination could allow not only more thorough documentation of inequities but also allow informed decision making about policies and programs intended to promote racial equity. SIGNIFICANCE STATEMENT: To our knowledge, this is the first study that presents a framework for assessing structural racial discrimination across contexts, life course, and geography that is grounded in theory and in the lived experience of intended participants. Leading researchers and policy makers have called for improved measures of structural racism and discrimination and specifically for a lifecourse approach to measurement. This study is a step in that direction. CLASSIFICATION: Social Sciences.

A neuroimaging proof of principle study of Down's syndrome and dementia: ethical and methodological challenges in intrusive research.

BACKGROUND: Research into specific illnesses and the development of new treatments may only become possible as new technologies become available. When used for research, such technologies may best be described as 'intrusive', in that they require a considerable willingness and commitment on the part of the participants. This has increasingly been the case for brain disorders and illnesses where novel neuroimaging techniques, often combined with clinical and psychological assessments, have the potential to result in new understanding. People with intellectual disabilities (ID) have a history of under-representation as participants in research using such technologies and are therefore at risk of not receiving equal access to state-of-the-art treatments. We propose that 'intrusive' biomedical research is both possible and ethical in ID, and explore some of the methodological challenges by reference to a recent proof of principle study that used a relatively new ligand-based brain scanning technique in a group of volunteers with Down's syndrome. METHODS: Five overlapping stages of the study methodology were identified and evaluated for their acceptability to volunteers with mild to moderate ID through discussion, reflection, and analysis of structured feedback in the context of key policy documents, ethical guidelines and relevant legislation. RESULTS: Identification of key ethical and methodological challenges from reflective practice and participant feedback facilitated the emergence of strategies that permitted continual refinement of the study design. Important areas considered included (1) being clear about the purpose and scientific justification for the study; (2) reconciling the potential risks and benefits with relevant ethical guidelines and legislation; (3) identifying and implementing effective recruitment strategies; (4) optimising and assessing capacity to consent; and (5) making the 'intrusive' procedures as acceptable as possible to people with ID. CONCLUSION: We were able to demonstrate that a proof of principle study incorporating a novel brain scanning technique in a group of volunteers with ID was feasible, safe and well tolerated, despite the vulnerabilities of the study cohort and the intrusive nature of the research. We consider the study within an ethical and historical discourse about the principles that define current 'best practice' in ID research and propose a number of key recommendations for making intrusive research acceptable in people with ID.

SV40 associated miRNAs are not detectable in mesotheliomas.

BACKGROUND: Simian virus-40 (SV40) is a DNA tumour virus that was introduced into the human population with contaminated poliovirus vaccine, and its role in mesothelioma is widely debated. PCR based testing has been called into question, as false positives can be because of cross-reactivity with related viruses, or to laboratory contamination. The Institute of Medicine has recommended the development of more sensitive and specific tests to resolve this controversy. METHODS: We have characterized highly sensitive RT-PCR based assays that are specific for SV40-encoded microRNAs (miRNAs), as an alternative to current testing methods. RESULTS: Using this sensitive and specific detection method, we were unable to identify SV40 miRNA expression in human malignant pleural mesothelioma (MM) samples. CONCLUSION: Our work indicates that SV40 miRNAs are not likely to contribute to mesothelioma tumourogenesis, but highlights the value of this approach when compared with the relatively unspecific current testing methods.

Associations between work schedule characteristics and occupational injury and illness.

BACKGROUND: Nurses often endure working irregular day, night and evening shifts as well as mandatory overtime (i.e. employer-imposed work time in excess of one's assigned schedule). While these work characteristics are examined as potential risks for nurses' safety and health, it is not clear whether negative health impacts occur simply because of working long hours or in combination with other mechanisms. AIM: This study investigates how these work characteristics are associated with nurses' work-related injury and illness over and above long work hours. METHODS: In this cross-sectional study, questionnaire data were collected from a sample of 655 registered nurses in the Philippines. Multiple logistic regression was used to assess associations of shift work and mandatory overtime with four work-related health outcomes. RESULTS: After weekly work hours, shift length and demographic variables were accounted for, non-day shifts were associated with work-related injury [odds ratio (OR) = 1.54; 95% confidence interval (CI): 1.07, 2.24] and work-related illness (OR = 1.48; 95% CI: 1.02, 2.16). Also, frequency of working mandatory overtime was associated with work-related injury (OR = 1.22; 95% CI: 1.06, 1.41), work-related illness (OR = 1.19; 95% CI: 1.04, 1.37) and missing more than 2 days of work because of a work-related injury or illness (OR = 1.25; 95% CI: 1.08, 1.44). CONCLUSIONS: These findings suggest that non-day shifts and mandatory overtime may negatively impact nurses' health independent of working long hours. Mechanisms through which these work characteristics affect health, such as circadian rhythm disturbance, nurse-to-patient ratios and work-family conflict, should be examined in future studies.

Neighbourhood environment as a predictor of television watching among girls.

BACKGROUND: Television watching, a sedentary activity, has been associated with overweight in children. While the family environment is known to influence television watching, little is known about the influence of the neighbourhood environment. This study is an exploratory examination of the association of socioeconomic characteristics of the neighbourhood environment with television watching among 9-10 year old girls. METHODS: Data collected by the Berkeley site of the National Heart, Lung and Blood Institute Growth and Health Study (NGHS) in 1987-8 from 787 girls who had a complete set of measurements relevant to the analysis were used. These measures included parental education, household income, race and weekly hours spent watching television. Addresses of the girls were geocoded and the median household income for the census tracts in which they lived was used to indicate neighbourhood socioeconomic characteristics. Multilevel modelling procedures were used to estimate fixed effect coefficients for individual and neighbourhood level variables. RESULTS: Living in high income areas was associated with less television watching, a finding that held even when controlling for parental education, household income and race. Race and parental education were also associated with television watching. CONCLUSION: Television watching among girls was associated not only with the socioeconomic characteristics of their households, but also of their neighbourhoods. Future studies should explore the mechanisms that mediate this relation and determine if these results are generalisable to other populations.

JC virus minor capsid proteins Vp2 and Vp3 are essential for virus propagation.

Virus-encoded capsid proteins play a major role in the life cycles of all viruses. The JC virus capsid is composed of 72 pentamers of the major capsid protein Vp1, with one of the minor coat proteins Vp2 or Vp3 in the center of each pentamer. Vp3 is identical to two-thirds of Vp2, and these proteins share a DNA binding domain, a nuclear localization signal, and a Vp1-interacting domain. We demonstrate here that both the minor proteins and the myristylation site on Vp2 are essential for the viral life cycle, including the proper packaging of its genome.

Levels of analysis for the study of environmental health disparities.

Reducing racial/ethnic and socioeconomic environmental health disparities requires a comprehensive multilevel conceptual and quantitative approach that recognizes the various levels through which environmental health disparities are produced and perpetuated. We propose a conceptual framework that incorporates the micro level, contained within the local level, which in turn is contained within the macro level. We discuss the utility of multilevel techniques to examine environmental level (both physical and social) and individual-level factors to appropriately quantify and improve our understanding of environmental health disparities. We discuss the reasoning and the methodological approach behind multilevel modeling, including differentiating between individual and contextual influences on individual outcomes. Next we address the questions and principles that guide the choice of levels or geographic units in multilevel studies. Finally, we address the ways in which different data sources can be combined to produce suitable data for multilevel analyses. We provide some examples of how such data sources can be linked to create multilevel data structures, and offer suggestions to facilitate the integration of multilevel techniques in environmental health disparities research and monitoring.

Multiple-year water balance of soil covers in a semiarid setting.

Surface covers are used to isolate contaminants in hazardous and low-level radioactive sites for time frames ranging from hundreds of years to millennia or more. In the absence of data for such durations, the long-term performance of surface barriers can only be represented with short-term tests or inferred from analogs and modeling. This paper provides evidence of field performance of soil covers for periods up to 17 yr. The results of lysimeter studies from a semiarid site in Washington State show that a cover design known as the Hanford Barrier, which consists of 1.5 m of silt loam above a sand-gravel capillary break, can nearly eliminate drainage. The results were similar if plants were present or not, demonstrating the robustness of the design. Furthermore, reducing the silt loam thickness to 1.0 m (as might occur via erosion), with or without plants, did not lead to drainage. When irrigated to mimic 3x average precipitation conditions, the vegetated Hanford Barrier continued to prevent drainage. Overall, the results showed no loss in performance during the 17 yr of testing. Only when plants were eliminated completely from the 3x precipitation test did drainage occur (rates ranged from 6 to 16 mm yr(-1)). In a separate test, replacing the top 0.2 m of silt loam with dune sand and reducing the plant cover did not lead immediately to the onset of drainage, but soil matric heads within the silt loam noticeably increased. This observation suggests that dune sand migration onto a surface cover has the potential to reduce a cover's ability to minimize deep drainage.

Abnormal frontal activations related to decision-making in current and former amphetamine and opiate dependent individuals.

RATIONALE: There is converging evidence for impairments in decision-making in chronic substance users. In the light of findings that substance abuse is associated with disruptions of the functioning of the striato-thalamo-orbitofrontal circuits, it has been suggested that decision-making impairments are linked to frontal lobe dysfunction. We sought to investigate this possibility using functional neuroimaging. METHODS: Decision-making was investigated using the Cambridge Risk Task during H2(15)O PET scans. A specific feature of the Risk Task is the decisional conflict between an unlikely high reward option and a likely low reward option. Four groups, each consisting of 15 participants, were compared: chronic amphetamine users, chronic opiate users, ex-drug users who had been long-term amphetamine/opiate users but are abstinent from all drugs of abuse for at least 1 year and healthy matched controls without a drug-taking history. RESULTS: During decision-making, control participants showed relatively greater activation in the right dorsolateral prefrontal cortex, whereas participants engaged in current or previous drug use showed relatively greater activation in the left orbitofrontal cortex. CONCLUSION: Our results indicate a disturbance in the mediation by the prefrontal cortex of a risky decision-making task associated with amphetamine and opiate abuse. Moreover, this disturbance was observed in a group of former drug users who had been abstinent for at least 1 year.

Early events in the life cycle of JC virus as potential therapeutic targets for the treatment of progressive multifocal leukoencephalopathy.

The human polyomavirus, JC virus (JCV), is the etiological agent of progressive multifocal leukoencephalopathy (PML). PML occurs almost exclusively in the setting of severe and prolonged immunosuppression and it remains an important and life-threatening complication in the acquired immunodeficiency syndrome (AIDS) population. Several drugs that target DNA replication have shown efficacy at inhibiting JCV replication in vitro but none to date have shown in vivo efficacy. The authors' laboratory has been studying early events that contribute to infection of susceptible cells by JCV. They previously demonstrated that infection of glial cells by JCV requires clathrin-dependent endocytosis and that this early step in the viral life cycle can be blocked by the antipsychotic drug, chlorpromazine. As chlorpromazine is associated with the development of extrapyramidal symptoms that may be heightened in AIDS patients, the authors sought to test the atypical antipsychotic, clozapine, for antiviral activity against JCV. In this report, the authors show that clozapine is as effective as chlorpromazine at inhibiting infection. They further demonstrate that low-dose combinations of both drugs synergistically inhibit infection.

Use of monoclonal antibodies developed against chicken coccidia (Eimeria) to study invasion and development of Eimeria reichenowi in Florida sandhill cranes (Grus canadensis).

Eimeria gruis and Eimeria reichenowi are common coccidial parasites of a number of species of cranes. Until recently, little was known about either the site for invasion or the dynamics of early development of the crane coccidia because of the difficulty of identifying sporozoites and early developmental stages of these parasites by conventional staining methods. In the present study, monoclonal antibodies (MAbs) elicited against Eimeria spp. of chickens and turkeys were found to cross-react with sporozoites and developmental stages of E. reichenowi in the tissues of Florida sandhill cranes (Grus canadensis). With these Mabs, E. reichenowi sporozoites were found in specimens taken at 6 hr postinoculation (PI) from just proximal to Meckel's diverticulum in the jejunum to the ileocecal juncture. Fewer were found in the ceca and rectum and none in the duodenal loop. At 24 hr PI, there were markedly fewer sporozoites and their location had shifted to the duodenum. No stages were seen in intestinal cells at 5 days PI (DPI), but trophozoites had developed in the liver and spleen. At 10 DPI, sexual stages were detected in the intestine from the duodenal loop through Meckel's diverticulum but not in other organs. By 14 DPI, numerous developmental stages were detected in the intestine (ceca and jejunum), liver, and lungs but not in the heart, kidney, or brain. The number, location, and maturity of the stages in the ceca differed markedly from those in the jejunum.

Species variation in osmotic, cryoprotectant, and cooling rate tolerance in poultry, eagle, and peregrine falcon spermatozoa.

Potential factors influencing spermatozoa survival to cryopreservation and thawing were analyzed across a range of the following avian species: domestic chicken (Gallus domesticus), domestic turkey (Meleagris gallopavo), golden eagle (Aquila chrysaetos), Bonelli's eagle (Hieraaetus fasciatus), imperial eagle (Aquila adalberti), and peregrine falcon (Falco peregrinus). Studies focused on spermatozoa tolerance to the following: 1) osmotic stress, 2) different extracellular concentrations of the cryoprotectant dimethylacetamide (DMA), 3) equilibration times of 1 versus 4 h, 4) equilibration temperature of 4 versus 21 degrees C, and 5) rapid versus slow cooling before cryopreservation and standard thawing. Sperm viability was assessed with the live/dead stain (SYBR-14/propidium iodine). Sperm viability at osmolalities >/=800 mOsm was higher (P: < 0.05) in raptor than poultry semen. Return to isotonicity after exposure to hypertonicity (3000 mOsm) decreased (P: < 0.05) number of viable spermatozoa in chicken, turkey, and golden and Bonelli's eagle spermatozoa but not in imperial eagle or peregrine falcon spermatozoa. Differences were found in spermatozoa resistance to hypotonic conditions, with eagle species demonstrating the most tolerance. Semen, equilibrated for 1 h (4 degrees C) in diluent containing DMA (> or =2.06 M), experienced decreased (P: < 0. 05) spermatozoa survival in all species, except the golden eagle and peregrine falcon. Number of surviving spermatozoa diminished progressively with increasing DMA concentrations in all species. Increased equilibration temperature (from 4 to 21 degrees C) markedly reduced (P: < 0.05) spermatozoa survival in all species except the Bonelli's eagle and turkey. Rapid cooling was detrimental (P: < 0.05) to spermatozoa from all species except the imperial eagle and the chicken. These results demonstrate that avian spermatozoa differ remarkably in response to osmotic changes, DMA concentrations, equilibration time, temperature, and survival after fast or slow freezing. These differences emphasize the need for species-specific studies in the development and enhancement of assisted breeding for poultry and endangered species.

Prevalence of cardiac valve abnormalities in afebrile injection drug users.

OBJECTIVES: To determine the prevalence of occult valvular pathology in afebrile injection drug users (IDUs) compared with an afebrile, non-IDU population. To characterize the type of valvular pathology present in light of current recommendations regarding periprocedural antibiotic prophylaxis against endocarditis. METHODS: This was a comparative, cross-sectional study involving a convenience sample of 98 patients with a history of injection drug use, and 99 non-IDU patients presenting to a large urban ED. Patients were excluded if they had one or more of the following: a history of cardiac valve abnormality, a history of endocarditis, fever on presentation, or a cardiac murmur. Data were collected that included demographics, medical history, and details of injection drug use. Transthoracic echocardiography (echo) was performed on each subject in the ED, and read in a blinded fashion by a single board-certified cardiologist. RESULTS: Among 98 IDUs and 99 non-IDUs, 12% of the IDUs had aortic valve thickening, compared with 5.1% of the non-IDUs (99% CI for difference of 7.8% = -3.0% to 18.6%). Forty-four percent of the IDUs had mitral valve thickening, compared with 25% of the non-IDUs (99% CI for difference of 18.3% = 0.9% to 35.7%). Eleven percent of the IDUs vs 1% of the non-IDUs had tricuspid valve thickening (99% CI for difference of 10.4% = 1.6% to 19.2%). No patient had pulmonic valve thickening. Six percent of the IDUs vs 0% of the non-IDUs had mitral annulus thickening (99% CI for difference of 6.3% = -0.1% to 12.8%). Twelve percent of the IDUs vs 3% of the non-IDUs had mitral chordae thickening (99% CI for difference of 9.5% = -0.4% to 19.4%). Tricuspid chordae thickening was recorded in 2% of the IDUs vs 0% of the non-IDUs (99% CI for difference of 2.1% = -1.7% to 6.0%). Most important, the prevalence of valvular regurgitation was small, and evenly distributed in the two groups. No valvular vegetations were seen. CONCLUSION: Both non-IDUs and IDUs have occult valvular pathology. There is an increased prevalence in IDUs of tricuspid and mitral valve thickening. The prevalence of valvular regurgitation, a reported indication for periprocedural antibiotic prophylaxis, was small and the affected valves were not statistically different between the two groups. These findings question the selected routine use of antibiotic prophylaxis in IDU patients undergoing invasive procedures.

Identification, inheritance, and linkage of B-G-like and MHC class I genes in cranes.

We identified B-G-like genes in the whooping and Florida sandhill cranes and linked them to the major histocompatibility complex (MHC). We evaluated the inheritance of B-G-like genes in families of whooping and Florida sandhill cranes using restriction fragment patterns (RFPs). Two B-G-like genes, designated wcbg1 and wcbg2, were located within 8 kb of one another. The fully sequenced wcbg2 gene encodes a B-G IgV-like domain, an additional Ig-like domain, a transmembrane domain, and a single heptad domain typical of alpha-helical coiled coils. Patterns of restriction fragments in DNA from the whooping crane and from a number of other species indicate that the B-G-like gene families of cranes are large with diverse sequences. Segregation of RFPs in families of Florida sandhill cranes provide evidence for genetic polymorphism in the B-G-like genes. The restriction fragments generally segregated in concert with MHC haplotypes assigned by serological typing and by single stranded conformational polymorphism (SSCP) assays based in the second exon of the crane MHC class I genes. This study supports the concept of a long-term association of polymorphic B-G-like genes with the MHC. It also establishes SSCP as a means for evaluating MHC genetic variability in cranes.

Pharmacists' attitudes about pharmacy sale of needles/syringes and needle exchange programs in a city without needle/syringe prescription laws.

We assessed pharmacists' practices for needle and syringe (NS) sales and their attitudes toward a needle exchange program through a telephone survey of 75 randomly selected pharmacies in Baltimore, Maryland, where possession of drug paraphernalia is illegal but where NS can be purchased without a prescription. Pharmacists' (n=46) procedures for NS sales included asking for picture identification (54%), requiring a prescription (34%), or requiring a diabetic identification (DID, 34%) for NS purchase; multiple responses were allowed. The median number of prescription and nonprescription NS sold per month was 950. Most (86.6%) pharmacists reported selling NS without prescriptions at their discretion. Pharmacists sold a median of 16 nonprescription NS per month. Pharmacists who required prescriptions or DID (56.5%) sold nonprescription NS significantly less often than those who did not require prescriptions or DID (p=.007). Most pharmacists (87%) were aware of the needle exchange program, 78.3% supported the program, and 67.4% supported selling nonprescription NS in pharmacies. Although there was no difference in anticipated effects of needle exchange or in support for needle exchange between pharmacists who did or did not require prescriptions, DID, or both, pharmacists who did require these items were significantly less likely to support pharmacy sales of nonprescription NS than pharmacists with less restrictive sales policies (p=.04). Although most pharmacists surveyed supported access to sterile NS by injection drug users through a needle exchange program, there was a diversity of approaches to nonprescription NS sales among pharmacists in a city that does not require prescriptions for access to sterile NS. Most supported nonpharmacy needle exchange programs, and more than one half limited injection drug users' access to NS through restrictive sales practices. To reduce injection drug users' exposure to HIV, pharmacists should be educated about HIV prevention and injection drug use and be included in development of HIV prevention programs, including legal pharmacy NS sales.

Combined cardiac marker approach with adjunct two-dimensional echocardiography to diagnose acute myocardial infarction in the emergency department.

STUDY OBJECTIVE: To evaluate a combined cardiac marker approach with adjunct two-dimensional echocardiography in diagnosing acute myocardial infarction (AMI) in the emergency department. METHODS: This prospective, cohort study enrolled 190 patients aged 18 years and older who presented to the ED of a county teaching hospital and were admitted with chest pain suggestive of AMI. A standardized history and physical examination were performed. Serum sampling for myoglobin and creatine kinase-MB (CK-MB) was done at the time of presentation (time 0) and 3 hours later (time 3 hours). An echocardiographic study was obtained, and a left ventricular wall motion score was derived. RESULTS: Using World Health Organization criteria, 21 patients (11.2%) with AMI were identified. The serum markers were found to be clinically and statistically different between AMI and non-AMI groups at both time 0 and time 3 hours. Receiver operator characteristic curves were used to determine a "positive" myoglobin level at 88.7 ng/mL or higher at either time point, and a "positive" CK-MB level at 11.9 ng/mL or higher; these were used as the optimal cutoff values to predict AMI in the ED. Serum myoglobin was a more sensitive marker (90.5%) than CK-MB (81.0%). However, CK-MB was more specific (99.4%) than myoglobin (88.4%). A combination of both tests, which was rated positive if either test was positive, was a superior predictor overall, with a 100% capture rate of AMI patients and a 91.2% specificity. No significant difference in echocardiographic scores was appreciated in the AMI group compared with the non-AMI group (16.9 +/- 1.5 versus 15.3 +/- .5, respectively; P = .3252). CONCLUSION: Serum myoglobin shows greater sensitivity but is less specific than CK-MB in the early detection of AMI. Use of a combination of both rapid assays during a 3-hour time period in the ED appears to be superior to use of either enzyme assay alone. Two-dimensional echocardiography does not appear to be helpful in diagnosing AMI in the ED.

Lumbosacral spine: early and delayed MR imaging after administration of an expanded dose of gadopentetate dimeglumine in healthy, asymptomatic subjects.

PURPOSE: To determine normal magnetic resonance (MR) imaging enhancement characteristics of the lumbosacral spine after intravenous administration of an expanded dose of gadopentetate dimeglumine. MATERIALS AND METHODS: T1-weighted MR images of the lumbosacral spine were acquired before and after injection of 0.3 mmol/kg gadopentetate dimeglumine in 12 healthy subjects (eight men, four women; age range, 22-57 years). RESULTS: In 10 (91%) of the 11 subjects who completed the investigation, multifocal linear enhancement within the thecal sac that generally extended from the conus to the nerve-root sheaths was demonstrated. In all cases, enhancement was seen in the facet joints and the intervertebral disks parallel to the vertebral end-plates. CONCLUSION: After an expanded dose of intravenous gadopentetate dimeglumine, multiple intrathecal and extrathecal structures were enhanced. Recognition of normal enhancement patterns after an expanded gadopentetate dimeglumine dose is important because such enhancement after routine injection of 0.1 mmol/kg gadopentetate dimeglumine is often thought to indicate disease.

A complex alloantigen system in Florida sandhill cranes, Grus canadensis pratensis: evidence for the major histocompatibility (B) system.

The B blood group system constitutes the major histocompatibility complex (Mhc) in birds. The Mhc is a cluster of genes largely devoted to the processing and presentation of antigen. The Mhc is highly polymorphic in many species and, thus, useful in the evaluation of genetic diversity for fitness traits within populations of a variety of animals. Correlations found between particular Mhc haplotypes and resistance to certain diseases emphasize the importance of understanding the functional significance of diversity of the Mhc, particularly in species threatened with extinction. As part of studies focused on genetic diversity in wild birds, serological techniques were used to define a highly polymorphic alloantigen system in seven families of Florida sandhill cranes (Grus canadensis pratensis). The results of analyses with antisera produced within the crane families and with chicken Mhc antigen-specific reagents revealed a single major alloantigen system that is likely the Mhc of the Florida sandhill crane. Preliminary experiments indicate that these crane alloantisera will provide a means of defining the Mhc in other species of cranes.

Imaging of cerebral infarction caused by atrial myxoma.

We describe the radiologic investigation of two patients with primary left atrial myxoma who presented with embolic manifestations in the brain. MRI and CT showed multiple infarcts, while the cardiac atrial mass was demonstrated in one of the patients by MRI and in both by echocardiography.

Environmental contaminants in nonviable eggs of the endangered Mississippi sandhill crane (Grus canadensis pulla).

Our objectives were to determine if concentrations of environmental pollutants and microbial contamination in nonviable eggs of the endangered Mississippi sandhill crane (Grus canadensis pulla) contributed to egg failure. Six eggs collected in 1990 and four in 1991 contained only background levels of organochlorine pesticides and polychlorinated biphenyls (PCBs), and tests for microbial contamination were all negative. Two eggs contained late dead embryos, but neither revealed obvious abnormalities. Three eggs contained potentially harmful concentrations (23, 39, 146 pg/g, wet mass) of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), based on 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ) for combined compounds. Because of the scarcity of material suitable for laboratory examination and the endangered status of the crane, we recommend that nonviable eggs continue to be monitored for toxic pollutants.