Stable magnetic remanence in antiferromagnetic goethite.

Goethite, known to be antiferromagnetic, acquires thermoremanent magnetization at its Neel temperature of 120 degrees C. This remanence, extremely stable, is due to the presence of unbalanced spins in the antiferromagnetic structure; the spins may result from grain size, imperfections, or impurities.

Cardiorespiratory fitness and white matter integrity in Alzheimer's disease.

The objective of this study was to investigate the relationship between cardiorespiratory (CR) fitness and the brain's white matter tract integrity using diffusion tensor imaging (DTI) in the Alzheimer's disease (AD) population. We recruited older adults in the early stages of AD (n = 37; CDR = 0.5 and 1) and collected cross-sectional fitness and diffusion imaging data. We examined the association between CR fitness (peak oxygen consumption [VO2peak]) and fractional anisotropy (FA) in AD-related white matter tracts using two processing methodologies: a tract-of-interest approach and tract-based spatial statistic (TBSS). Subsequent diffusivity metrics (radial diffusivity [RD], mean diffusivity [MD], and axial diffusivity [A × D]) were also correlated with VO2peak. The tract-of-interest approach showed that higher VO2peak was associated with preserved white matter integrity as measured by increased FA in the right inferior fronto-occipital fasciculus (p = 0.035, r = 0.36). We did not find a significant correlation using TBSS, though there was a trend for a positive association between white matter integrity and higher VO2peak measures (p < 0.01 uncorrected). Our findings indicate that higher CR fitness levels in early AD participants may be related to preserved white matter integrity. However to draw stronger conclusions, further study on the relationship between fitness and white matter deterioration in AD is necessary.

Maternal behavior of beef cows at parturition.

Over an 11-yr period maternal behavior, calf birth weight and calf condition were recorded within 24 h for 2,684 parturitions. Maternal behavior was rated on a scale from 1 to 11, where 1 indicated extreme aggressiveness and 11 indicated no maternal attentiveness. Birth condition was rated on a scale from 1 to 9, with 9 being fattest and 1 thinnest. Respective breed means of Hereford, Angus, Charolais and Red POll were 6.2, 5.3, 6.0, and 5.7 for maternal behavior rating; 30.6, 27.3, 39.2 and 32.6 kg for birth weight, and 5.5, 4.7, 5.6 and 5.5 for birth condition. Heritability estimates for maternal rating, birth weight and birth condition were .06 +/- .01, .48 +/- .02 and .19 +/- .01, respectively. Genetic correlations between maternal rating and birth weight and condition were .04 +/- .05 and -.02 +/- .06, respectively. These results suggest that, in the population of cows studied, nongenetic influences were the primary cause of differences in aggressiveness of cows at parturition.

Insulin resistance and gray matter volume in neurodegenerative disease.

The goal of this study was to compare insulin resistance in aging and aging-related neurodegenerative diseases, and to determine the relationship between insulin resistance and gray matter volume (GMV) in each cohort using an unbiased, voxel-based approach. Insulin resistance was estimated in apparently healthy elderly control (HC, n=21) and neurodegenerative disease (Alzheimer's disease (AD), n=20; Parkinson's disease (PD), n=22) groups using Homeostasis Model Assessment of Insulin Resistance 2 (HOMA2) and intravenous glucose tolerance test (IVGTT). HOMA2 and GMV were assessed within groups through General Linear Model multiple regression. We found that HOMA2 was increased in both AD and PD compared to the HC group (HC vs. AD, p=0.002, HC vs. PD, p=0.003), although only AD subjects exhibited increased fasting glucose (p=0.005). Furthermore, our voxel-based morphometry analysis revealed that HOMA2 was related to GMV in all cohorts in a region-specific manner (p<0.001, uncorrected). Significant relationships were observed in the medial prefrontal cortex (HC), medial temporal regions (AD), and parietal regions (PD). Finally, the directionality of the relationship between HOMA2 and GMV was disease-specific. Both HC and AD subjects exhibited negative relationships between HOMA2 and brain volume (increased HOMA2 associated with decreased brain volume), while a positive relationship was observed in PD. This cross-sectional study suggests that insulin resistance is increased in neurodegenerative disease, and that individuals with AD appear to have more severe metabolic dysfunction than individuals with PD or PD dementia.

Alzheimer disease biomarkers are associated with body mass index.

OBJECTIVE: Both low and high body mass index (BMI) has been associated with cognitive impairment and dementia risk, including Alzheimer disease (AD). We examined the relationship of BMI with potential underlying biological substrates for cognitive impairment. METHODS: We analyzed cross-sectional data from participants enrolled in the Alzheimer's Disease Neuroimaging Initiative (ADNI) with PET imaging using Pittsburgh Compound B (PiB, n = 101) or CSF analyses (n = 405) for ß-amyloid peptide (Aß) and total tau. We assessed the relationship of CSF biomarkers and global PiB uptake with BMI using linear regression controlling for age and sex. We also assessed BMI differences between those who were and were not considered biomarker positive. Finally, we assessed BMI change over 2 years in relationship to AD biomarkers. RESULTS: No dementia, mild cognitive impairment (MCI), and AD groups were not different in age, education, or BMI. In the overall sample, CSF Aß (ß = 0.181, p < 0.001), tau (ß = -0.179, p < 0.001), tau/Aß ratio (ß = -0.180, p < 0.001), and global PiB uptake (ß = -0.272, p = 0.005) were associated with BMI, with markers of increased AD burden associated with lower BMI. Fewer overweight individuals had biomarker levels indicative of pathophysiology (p < 0.01). These relationships were strongest in the MCI and no dementia groups. CONCLUSIONS: The presence and burden of in vivo biomarkers of cerebral amyloid and tau are associated with lower BMI in cognitively normal and MCI individuals. This supports previous findings of systemic change in the earliest phases of the disease. Further, MCI in those who are overweight may be more likely to result from heterogeneous pathophysiology.

Reduced gray matter volume in normal adults with a maternal family history of Alzheimer disease.

OBJECTIVE: A consistently identified risk factor for Alzheimer disease (AD) is family history of dementia, with maternal transmission significantly more frequent than paternal transmission. A history of maternal AD may be related to AD-like glucose consumption in cognitively healthy subjects. In this cross-sectional study, we tested whether cognitively healthy people with a family history of AD have less gray matter volume (GMV), an endophenotype for late-onset AD, than individuals with no family history, and whether decreases in GMV are different in subjects with a maternal family history. METHODS: As part of the Kansas University Brain Aging Project, 67 cognitively intact individuals with a maternal history of late-onset AD (FHm, n = 16), a paternal history of AD (FHp, n = 8), or no parental history of AD (FH-, n = 43), similar in age, gender, education, and Mini-Mental State Examination score, were scanned at 3 T. We used voxel-based morphometry to examine GMV differences between groups, controlling for age, gender, and apoE4. RESULTS: Cognitively healthy individuals with a family history of late-onset AD had significantly decreased GMV in the precuneus, middle frontal, inferior frontal, and superior frontal gyri compared with FH- individuals. FHm subjects had significantly smaller inferior frontal, middle frontal, precuneus, and lingual gyri compared with FH- and FHp subjects. CONCLUSIONS: Overall, maternal family history of Alzheimer disease (AD) in cognitively normal individuals is associated with lower gray matter volume in AD-vulnerable brain regions. These data complement and extend reports of cerebral metabolic differences in subjects with a maternal family history.

How many people does it take to operate a picture archiving and communication system?

The most frequently asked question without a correct answer is: "Just how many people does it take to operate a picture archiving and communication system (PACS)?" At Texas Children's Hospital, our consensus is that we do not yet know. As soon as we felt we had adequate staffing to provide timely response for routine services, we found that including the Intensive Care Units (ICUs) increased our demand for urgent response beyond our capacity. The addition of inpatient bedside imaging to PACS also increased the demand for round-the-clock and weekend PACS services. Our answer to the staffing question changes every year, in accordance with changes in the scope of services that our PACS is expected to provide. Our administration drew up a 5-year plan for PACS implementation, concentrating on purchase and installation of equipment, but neglected to estimate requirements for full-time equivalents (FTEs) for PACS. Our administration reasonably assumed that existing employees would be galvanized into PACS personnel. It is now clear that new FTEs need to be created strictly for the PACS service. Our 5-year plan also did not anticipate significant changes in the extent of our healthcare enterprise. Our PACS accommodates limited remote service: providing a PACS Analyst to travel to the site when a problem is not resolved remotely is another demand on staffing. Our PACS service was formed using staffing numbers based on assumptions about the minimum number of employees needed to perform routine duties, field trouble calls, conduct training, and work on special projects, such as adding new acquisition modalities or troubleshooting longstanding problems. This staffing was based on a single shift operation, with on-call coverage for second, third, and weekend shifts. The number of employees also considered absences for vacation, sick leave, and training. The service has administrative overhead that should be covered by a secretary. Someone is also needed to supervise the team. Once the number of personnel is determined, detailed definition of qualifications and responsibilities is required. Each job description must accurately reflect what is expected of the employee, but must be constructed in such a way to be graded appropriately by Human Resources, without excluding potentially desirable applicants. In addition to competitive pay, other factors play an important role in recruiting and retention. These include training that the hospital provides, opportunities for advancement, relief from menial duties, adequate working space and facilities, and opportunities for self-development. There is high turnover of personnel in computer services, and we are in a highly competitive market. The correct number of FTEs must consider that we will have to operate the PACS during periods when one or more positions are open or occupied by "greenhorns." In our case, where the vendor provides on-site service engineers, we are able to operate with fewer FTEs. The more distant and tenuous our vendor support, the more we would need to depend on hospital FTEs. While remote vendor maintenance is helpful, it is not useful in reducing the number of FTEs. Instead of adding PACS responsibilities to supervisors of imaging services, we are creating new PACS FTEs outside the PACS service. The idea is to give imaging supervisors the assets they need to perform the additional tasks involving PACS, such as first-line response to trouble, user training, and quality-control oversight. It also frees up PACS service personnel to deal with training and problems with customers outside the Radiology Department.

Maintaining continuity of clinical operations while implementing large-scale filmless operations.

Texas Children's Hospital is a pediatric tertiary care facility in the Texas Medical Center with a large-scale, Digital Imaging and Communications in Medicine (DICOM)-compliant picture archival and communications system (PACS) installation. As our PACS has grown from an ultrasound niche PACS into a full-scale, multimodality operation, assuring continuity of clinical operations has become the number one task of the PACS staff. As new equipment is acquired and incorporated into the PACS, workflow processes, responsibilities, and job descriptions must be revised to accommodate filmless operations. Round-the-clock clinical operations must be supported with round-the-clock service, including three shifts, weekends, and holidays. To avoid unnecessary interruptions in clinical service, this requirement includes properly trained operators and users, as well as service personnel. Redundancy is a cornerstone in assuring continuity of clinical operations. This includes all PACS components such as acquisition, network interfaces, gateways, archive, and display. Where redundancy is not feasible, spare parts must be readily available. The need for redundancy also includes trained personnel. Procedures for contingency operations in the event of equipment failures must be devised, documented, and rehearsed. Contingency operations might be required in the event of scheduled as well as unscheduled service events, power outages, network outages, or interruption of the radiology information system (RIS) interface. Methods must be developed and implemented for reporting and documenting problems. We have a Trouble Call service that records a voice message and automatically pages the PACS Console Operator on duty. We also have developed a Maintenance Module on our RIS system where service calls are recorded by technologists and service actions are recorded and monitored by PACS support personnel. In a filmless environment, responsibility for the delivery of images to the radiologist and referring physician must be accepted by each imaging supervisor. Thus, each supervisor must initiate processes to verify correct patient and examination identification and the correct count and routing of images with each examination.

Branching out with filmless radiology.

Texas Children's Hospital, a 456 bed pediatric hospital located in the Texas Medical Center, has been constructing a large-scale picture archiving and communications system (PACS), including ultrasound (US), computed tomography (CT), magnetic resonance (MR), and computed radiography (CR). Until recently, filmless radiology operations have been confined to the imaging department, the outpatient treatment center, and the emergency center. As filmless services expand to other clinical services, the PACS staff must engage each service in a dialog to determine the appropriate level of support required. The number and type of image examinations, the use of multiple modalities and comparison examinations, and the relationship between viewing and direct patient care activities have a bearing on the number and type of display stations provided. Some of the information about customer services is contained in documentation already maintained by the imaging department. For example, by a custom report from the radiology information system (RIS), we were able to determine the number and type of examinations ordered by each referring physician for the previous 6 months. By compiling these by clinical service, we were able to determine our biggest customers by examination type and volume. Another custom report was used to determine who was requesting old examinations from the film library. More information about imaging usage was gathered by means of a questionnaire. Some customers view images only where patients are also seen, while some services view images independently from the patient. Some services use their conference rooms for critical image viewing such as treatment planning. Additional information was gained from geographical surveys of where films are currently produced, delivered by the film library, and viewed. In some areas, available space dictates the type and configuration of display station that can be used. Active participation in the decision process by the clinical service is a key element to successful filmless operations.

Care and feeding of a staff for filmless radiology.

Texas Children's Hospital, a definitive care pediatric hospital located in the Texas Medical Center, has been constructing a large-scale picture archival and communications system (PACS) including ultrasound (US), computed tomography (CT), magnetic resonance (MR), and computed radiography (CR). Developing staffing adequate to meet the demands of filmless radiology operations has been a continuous challenge. Overall guidance for the PACS effort is provided by a hospital-level PACS Committee, a department-level PACS Steering Committee, and an Operations Committee. Operational Subcommittees have been formed to address service-specific implementation, such as the Emergency Center Operations Subcommittee. These committees include membership by those affected by the change, as well as those effecting the change. Initially, personnel resources for PACS were provided through additional duties of existing imaging service personnel. As the PACS effort became more complex, full-time positions were created, including a PACS Coordinator, a PACS Analyst, and a Digital Imaging Assistant. Each position requires a job description, qualifications, and personnel development plans that are difficult to anticipate in an evolving PACS implementation. These positions have been augmented by temporary full-time assignments, position reclassifications, and cross-training of other imaging personnel. Imaging personnel are assisted by other hospital personnel from Biomedical Engineering and Information Services. Ultimately, the PACS staff grows to include all those who must operate the PACS equipment in the normal course of their duties. The effectiveness of the PACS staff is limited by their level of their expertise. This report discusses our methods to obtain training from outside our institution and to develop, conduct, and document standardized in-house training. We describe some of the products of this work, including policies and procedures, clinical competency criteria, PACS inservice topics, and an informal PACS newsletter. As the PACS system software and hardware changes, and as our implementation grows, these products must to be revised and training must be repeated.