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Biomedical subjects

A L Anderson

Publications and source records attributed to A L Anderson.

At least 19 recordsLinked to original sources
PubMed2001

Quality-control issues on high-resolution diagnostic monitors.

Previous literature indicates a need for more data collection in the area of quality control of high-resolution diagnostic monitors. Throughout acceptance testing, which began in June 2000, stability of monitor calibration was analyzed. Although image quality on all monitors was found to be acceptable upon initial acceptance testing using VeriLUM software by Image Smiths, Inc (Germantown, MD), it was determined to be unacceptable during the clinical phase of acceptance testing. High-resolution monitors were evaluated for quality assurance on a weekly basis from installation through acceptance testing and beyond. During clinical utilization determination (CUD), monitor calibration was identified as a problem and the manufacturer returned and recalibrated all workstations. From that time through final acceptance testing, high-resolution monitor calibration and monitor failure rate remained a problem. The monitor vendor then returned to the site to address these areas. Monitor defocus was still noticeable and calibration checks were increased to three times per week. White and black level drift on medium-resolution monitors had been attributed to raster size settings. Measurements of white and black level at several different size settings were taken to determine the effect of size on white and black level settings. Black level remained steady with size change. White level appeared to increase by 2.0 cd/m2 for every 0.1 inches decrease in horizontal raster size. This was determined not to be the cause of the observed brightness drift. Frequency of calibration/testing is an issue in a clinical environment. The increased frequency required at our site cannot be sustained. The medical physics division cannot provide dedicated personnel to conduct the quality-assurance testing on all monitors at this interval due to other physics commitments throughout the hospital. Monitor access is also an issue due to radiologists' need to read images. Some workstations are in use 7 AM to 11 PM daily. An appropriate monitor calibration frequency must be established during acceptance testing to ensure unacceptable drift is not masked by excessive calibration frequency. Standards for acceptable black level and white level drift also need to be determined. The monitor vendor and hospital staff agree that currently, very small printed text is an acceptable method of determining monitor blur, however, a better method of determining monitor blur is being pursued. Although monitors may show acceptable quality during initial acceptance testing, they need to show sustained quality during the clinical acceptance-testing phase. Defocus, black level, and white level are image quality concerns, which need to be evaluated during the clinical phase of acceptance testing. Image quality deficiencies can have a negative impact on patient care and raise serious medical-legal concerns. The attention to quality control required of the hospital staff needs to be realistic and not have a significant impact on radiology workflow.

Calibration↗
PubMed2001

Trials and tribulations in deploying digital imaging network and picture archiving and communication system--film to filmless in 80 days.

The Naval Medical Center Portsmouth (NMCP) was constructed with the intention of deploying a picture archiving and communications system (PACS). All necessary infrastructures were installed and considerable planning was done during construction with the belief that this would make the deployment of the PACS much simpler. This was true during the early deployment; however, as time passed and the system was more heavily used, significant problems arose. User/operator-related and hardware/software-related problems were encountered. Although, most have been corrected, some have persisted and will require considerable manpower and/or fiscal resources to correct. The lesson learned is that no matter how much preparation is done for deploying PACS, many significant problems will surface as the system is used that will require the continued attention of the deployment project officer.

Computer Systems↗
PubMed2001

Hepatitis B virus transcription and replication.

Hepatitis B virus (HBV) replicates by the reverse transcription of the 3.5-kb viral pregenomic RNA. Therefore, the regulation of the transcription of the pregenomic RNA is a critical step in the viral life cycle. Various ubiquitous and liver-enriched transcription factors have been shown to modulate the level of RNA synthesis from the core promoter. The nuclear hormone receptors HNF4 and RXRalpha plus PPARalpha appear to have a critical role in governing pregenomic RNA synthesis from the core promoter in cell culture and probably represent a major determinant governing the hepatotropism of this virus. The level of 3.5-kb HBV RNA synthesis is approximately proportional to the level of viral replication in cell culture; however, this is not the case in the liver of HBV transgenic mice. Directly modulating the levels or activities of specific transcription factors known to regulate HBV transcription in cell culture can increase viral replication in HBV transgenic mice without greatly changing the levels of HBV transcripts. Various immune stimuli that alter transcription factor activities involved in regulating viral RNA synthesis can negatively affect viral replication without affecting HBV transcription. These observations suggest that in vivo very subtle changes in HBV transcription may contribute to large alterations, either negative or positive, in viral replication. Investigation of transcription factor-null HBV transgenic mice under various physiological conditions will be required to establish the putative role of specific transcription factors in regulating viral replication in vivo.

Journal Article↗
PubMed2000

High-resolution microPET imaging of carcinoembryonic antigen-positive xenografts by using a copper-64-labeled engineered antibody fragment.

Rapid imaging by antitumor antibodies has been limited by the prolonged targeting kinetics and clearance of labeled whole antibodies. Genetically engineered fragments with rapid access and high retention in tumor tissue combined with rapid blood clearance are suitable for labeling with short-lived radionuclides, including positron-emitting isotopes for positron-emission tomography (PET). An engineered fragment was developed from the high-affinity anticarcinoembryonic antigen (CEA) monoclonal antibody T84.66. This single-chain variable fragment (Fv)-C(H)3, or minibody, was produced as a bivalent 80 kDa dimer. The macrocyclic chelating agent 1,4,7, 10-tetraazacyclododecane-N,N',N", N"'-tetraacetic acid (DOTA) was conjugated to the anti-CEA minibody for labeling with copper-64, a positron-emitting radionuclide (t(1/2) = 12.7 h). In vivo distribution was evaluated in athymic mice bearing paired LS174T human colon carcinoma (CEA positive) and C6 rat glioma (CEA negative) xenografts. Five hours after injection with (64)Cu-DOTA-minibody, microPET imaging showed high uptake in CEA-positive tumor (17.9% injected dose per gram +/- 3.79) compared with control tumor (6.0% injected dose per gram +/- 1.0). In addition, significant uptake was seen in liver, with low uptake in other tissues. Average target/background ratios relative to neighboring tissue were 3-4:1. Engineered antibody fragments labeled with positron-emitting isotopes such as copper-64 provide a new class of agents for PET imaging of tumors.

Animals↗
PubMed1998

An apparatus for membrane-confined analytical electrophoresis.

A membrane-confined analytical electrophoresis apparatus for measuring the solution charge of macromolecules has been described previously (T. M. Laue et al., Anal. Biochem. 1989, 182, 377-382). Presented here is a design for this apparatus, which permits the on-line acquisition and display of absorbance data from up to 512 positions along an analysis chamber. Concentration distributions of macromolecules in solution can be monitored in the chamber to provide steady-state electrophoresis, electrophoretic mobility and diffusion measurements. Buffer chambers press semipermeable membranes against the open ends of a fused-silica cuvette to form the analysis chamber. This configuration permits both the flow of buffer and the establishment of an electric field across the cuvette, while retaining macromolecules in the field of view. Though a gel may be included in the analysis chamber, none is required for gradient stabilization. The volume of sample required for analysis is 8 microL, most of which is recoverable. Experimental conditions can be varied during study by simply changing the circulating buffer and/or the electric field. The analysis and buffer chambers are held in an aluminum housing that sits in an aluminum water jacket. The water jacket provides temperature control, shielding from external electrical noise and also serves as an optical mask. Plans for the cell assembly, optical system and the computer interface for data acquisition are provided. The assembly and operation of the apparatus and the analysis of data are described.

Electric Conductivity↗
PubMed1998

Nurse practitioners, certified nurse midwives, and physician assistants in California.

California's health care industry includes workers prepared in many ways to perform many jobs. One significant group of health care workers prepared to provide care that often overlaps with physician-generated services is known as "nonphysician providers." Commonly, this label refers to nurse practitioners (NPs), certified nurse midwives (CNMs), and physician assistants (PAs). In this article, we will describe this group in five main areas: (1) the characteristics of the current and projected workforce and programs preparing these professionals; (2) the current skill expectations and knowledge bases of each; (3) trends in the education of these health professionals; (4) innovative models of education of these health professionals; and (5) the inclusion of NPs, PAs, and CNMs in workforce planning in a changing health care system. We conclude that, particularly in light of the overlapping functions of this provider group with many physician functions, the NP, CNM, and NP workforces must be recognized and considered when planning for the future of the physician workforce.

California↗
PubMed1996

Practice environment for nurse practitioners in California. Identifying barriers.

Barriers exist that prevent nurse practitioners from using their primary health care knowledge and skills. We present the incidence of and specific barriers experienced by nurse practitioner respondents in California, the state with the largest number of nurse practitioners in the nation. A January 1995 survey was sent to all nurse practitioners certified in California to elicit their experiences regarding legal or social barriers in their practice, with space for an open-ended response. Of an estimated 3,895 nurse practitioners in California, 2,741 (70%) returned surveys. Most nurse practitioner (65%) respondents in California are providing primary care. Perceived barriers to practice are lack of prescriptive authority, lack of support from physicians, reimbursement difficulties, and lack of public awareness. Current barriers to nurse practitioner practice in California are similar to national barriers discovered in 1992 data. The development of interprofessional dialogue and the recognition of the contributions of all primary care professionals are some of the steps that can be taken to reduce these barriers and increase the use and effectiveness of nurse practitioners in primary care.

California↗
PubMed1995

Runner with gout and an aortic valve nodule.

A 33-yr-old male ran 10 miles, drank some beer, and developed pain in his left knee and ankle. He took some leftover antibiotics but was no better after 6 d, when a heart murmur and an aortic valve nodule were discovered. He was presumed to have endocarditis with septic arthritis and was started on intravenous antibiotics. On the second hospital day, synovial fluid analysis revealed acute gout, and the patient improved very rapidly on anti-gout therapy. The valvular nodule remained unexplained, but one very rare cause of valvular heart nodules is visceral gout. An unsuccessful attempt to resorb the nodule was made by using allopurinol. This patient demonstrates several points about gout in endurance athletes: 1) acute gout can mimic infectious endocarditis, 2) misdiagnosed or undertreated gout often leads to multiple joint involvement and sometimes to visceral tophi, and 3) athletes who exercise in warm weather and quench their thirst with cold beer are at risk for acute gout.

Acute Disease↗
PubMed1994

Calibration of a 241Am wound-monitoring system using Monte Carlo techniques.

Monte Carlo techniques have been used to establish calibration factors and to predict gamma spectra for well-defined measurements. These techniques are routinely used to predict shielding requirements and critical specifications. The Lawrence Livermore National Laboratory is researching the feasibility of using Monte Carlo techniques to establish calibration factors for in vivo measurement systems. A pilot study was conducted to demonstrate the use of the Monte Carlo technique to calibrate in vivo measurement systems, to predict the efficiency of a wound measurement system and compare the predicted efficiency with the measured efficiency, and to investigate the effects of the source geometry and the detector size on the measured efficiency. Results of this study demonstrate good agreement between the Monte-Carlo-predicted efficiency and the measured efficiency for a wound calibration phantom. The effects of the source geometry and the detector size tend to conform to the physical processes that govern the measurement process. These results demonstrate that the Monte Carlo technique accurately predicts the in vivo measurement efficiency if the characteristics of the attenuating material and the Monte Carlo source geometry are properly established.

Americium↗
PubMed1993

A comparison of techniques in the assessment of chest wall thickness and composition.

The thickness and composition of defined regions of the anterior chest wall are important factors in the assessment of pulmonary plutonium by low-energy x ray counting. Estimates of these quantities are reported for seven male subjects investigated by three laboratories using ultrasonic methods and by a fourth laboratory using magnetic resonance imaging. No important bias was found in any one laboratory's estimates of chest wall thickness relative to those of the others, but differences of up to 6 mm were noted for individual subjects. The discrepancies are believed principally to reflect the different sampling regimes adopted to reach a representative mean chest wall thickness over the region of interest from measurements at selected points. The adipose-tissue component was consistently found to be lower when assessed by magnetic resonance imaging compared with estimates by ultrasound, but the differences were unimportant in the context of plutonium assessment.

Adipose Tissue↗
PubMed1993

Radioimmunodetection of Hodgkin's disease and non-Hodgkin's lymphomas with monoclonal antibody to eosinophil peroxidase.

The purpose of this study was to determine if a radiolabeled murine monoclonal antibody (EOS) directed against eosinophil peroxidase would localize specifically to tumor sites in patients with lymphomas infiltrated by eosinophils. Ten patients with Hodgkin's disease and eosinophilia, three patients with non-Hodgkin's lymphomas and eosinophilia and five control patients received an intravenous injection of 3-10 mg of EOS antibody radiolabeled with 74-155 MBq (2.0-4.2 mCi) of 111In. At intervals of 24, 48 and 72 hr after injection, gamma camera images were obtained along with blood and urine specimens and the imaging results were correlated with the results of other staging modalities. As early as 24 hr after antibody injection, there was clear visualization of identifiable sites of lymphoma with eosinophilia greater than 1 cm in size, including the spleen, bone marrow and lymph nodes. Although EOS also localized nonspecifically to the liver and, in some patients, to the nasopharynx, there was no appreciable uptake in normal bone marrow, spleen, uninvolved lymph nodes, lymphomas without eosinophilia or various other pathologic conditions without eosinophilia. Except for transient pain at tumor sites in three patients, no adverse reactions were noted. We conclude that a radiolabeled monoclonal antibody directed against eosinophil peroxidase localizes to lymphoma sites infiltrated by eosinophils.

Adult↗
PubMed1992

Thalassemia minor: a risk factor for osteoporosis?

A case report of a 53 year old postmenopausal woman with severe osteoporosis occurring in association with beta thalassemia trait is presented. She was found to have marked axial osteopenia with lumbar spine bone mineral density that was more than three standard deviations below the mean, but had normal bone mineral density of the proximal radius. A biopsy of the iliac crest showed evidence of high turnover osteoporosis. Bone densitometry of the spine and hip in a consecutive series of eleven asymptomatic individuals with thalassemia trait also is reported. Bone mineral density was diminished in the spine (z-score = -0.78, P less than 0.03) and hip (z-score = -0.54, P = 0.05) of patients with thalassemia trait. It is postulated that thalassemia minor may be a risk factor for osteoporosis.

Adult↗
PubMed1991

Effectiveness of mist-blower applications of malathion and permethrin to foliage as barrier sprays for salt marsh mosquitoes.

Permethrin and malathion were applied as salt marsh mosquito barrier sprays by mist-blower to the shrub border of a park. At one and 24 h after treatment, mosquito landing counts in both insecticide treated areas declined by 80-90% relative to counts in an untreated control area. After 48 h, in the malathion-treated area, mosquito activity returned to levels observed in the control area. From 2 to 8 days post-treatment, mosquito landing counts in the permethrin-treated area remained depressed and significantly (P less than 0.01) different from the malathion-treated and control areas. On days 9 and 10 post-treatment, mosquito landing rates returned to high levels in the insecticide-treated and control areas.

Animals↗
PubMed1991

Radioimmunodetection of degranulated human eosinophils in mice: a potential model for imaging Hodgkin's disease and other pathologic conditions.

Various human tumors such as lymphomas and carcinomas sometimes contain extensive infiltration by degranulating eosinophils. To determine if degranulated eosinophils are suitable targets for immunolocalization, we performed in vivo distribution and imaging studies in mice, using EOS (a murine monoclonal antibody directed to human eosinophil peroxidase) labeled with indium-111. Adult mice were injected intravenously with radiolabeled EOS antibody or with similarly radiolabeled normal mouse IgG before receiving an intramuscular injection into the right thigh of homogenized human eosinophils adsorbed to latex microspheres. There was striking localization in the right thigh of the radiolabeled EOS antibody detectable by gamma imaging techniques as soon as 24 hr after injection. By contrast, there was little accumulation of radiolabeled normal IgG in the right thigh. We conclude that human eosinophil peroxidase is potentially a suitable target for radioimmunodetection and therapy of neoplasms and pathologic conditions that contain degranulating eosinophils.

Animals↗
PubMed1990

The sclerotic pedicle--how many causes are there?

The sclerotic pedicle is a commonly encountered roentgen sign that may be associated with numerous conditions, both benign and malignant. The following paper discusses the common as well as the unusual causes of this interesting phenomenon and demonstrates the radiographic presentations of the various etiologies.

Diagnosis, Differential↗
PubMed1990

Improved ultrasonic measurement techniques applied to assay of Pu and other transuranics in lung.

At the Lawrence Livermore National Laboratory, we are developing a system that will more accurately measure fat, muscle, and bone content from ultrasonic images of the chest wall. This paper describes a procedure that will allow chest-wall thickness to be determined to within +/- 1.5 mm (compared with the +/- 3-6 mm from current techniques) and may allow absolute errors in chest-wall composition to be reduced to +/- 4%.

Adipose Tissue↗
PubMed1989

Are dolls real? Developmental changes in the child's definition of reality.

Preschoolers (n = 20), second graders (n = 20), fifth graders (n = 20), and graduate-level college students (n = 20) were asked to determine the reality status of specific items, such as dolls and dreams, and to generate examples of real and not-real things. The criteria used for determining whether or not specific items were real differed significantly across the age range sampled and were strongly influenced by the type of items being judged. Criteria clearly changed with age, with item-specific criteria being substituted for more general verification criteria.

Child↗