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Biomedical subjects

T Fields

Publications and source records attributed to T Fields.

At least 19 recordsLinked to original sources
PubMed1999

Executive directors and community health centers--facing the healthcare transition.

This paper examines the impressions and experiences of administrators who manage Community Health Centers (CHCs) in Region VI, US Department of Health and Human Services, with the goal of identifying leadership skills and intrinsic values that are needed to run integrated service delivery sites. As the delivery of healthcare service shifts to health promotion and disease prevention, Community Health Centers are well positioned to assume major roles in this transition. However, some CHC administrators may need additional skills in order to address the changing healthcare environment. A survey of CHC Executive Directors was conducted to identify their impressions and experiences. Information obtained from this exploratory study should be beneficial in educating the next generation of healthcare administrators.

Administrative Personnel↗
PubMed1998

Accuracy of fluorocrit in determination of blood perflubron concentration.

Previous studies examining the radiosensitizing effects of perfluorochemical emulsions have based dose recommendations on a measurement known as fluorocrit. The fluorocrit is the proportion of blood volume occupied by perfluorochemicals and is measured using standard hematocrit procedures. This measurement is inherently crude and subject to error and variability between different individuals measuring the same sample. Furthermore, the fluorocrit method has not been compared to other quantitative methods to determine its reliability. The purpose of this study was to compare fluorocrit measurements to those obtained by gas chromatographic analysis. A 90% w/v perflubron emulsion was administered to six normal dogs once weekly for four weeks and peripheral blood samples were obtained at specified time points for analysis. A total of 123 blood samples were analyzed by both methods. The relationship between blood fluorocrit and plasma perflubron concentration measured by gas chromatography was examined using regression models. Based on the modest predictive value (r2 = 0.3683) of the derived statistical model, we conclude that fluorocrit measurement is an inaccurate method of estimation of blood perflubron concentration. Caution must, therefore, be exercised when extrapolating data and dose recommendations from reports of studies using flurocrit as the only estimate of blood perflubron concentration.

Animals↗
PubMed1997

Lymphocyte recruitment and the kinetics of adhesion receptor expression during the pulmonary immune response to particulate antigen.

The selectins and beta2 integrins participate in the recruitment of neutrophils in acute pulmonary inflammation. However, the cell adhesion receptors that mediate lymphocyte trafficking into the lung have not been defined. This study examined the relationship between cell adhesion molecules on the pulmonary vasculature and on lymphocytes recovered from the lung during a pulmonary immune response to intratracheal (I.T.) sheep red blood cells (SRBCs) in sensitized C57BL/6J mice. Silver-enhanced immunogold staining and reverse transcriptase polymerase chain reaction of lung tissues revealed sustained induction of VCAM-1, E-selectin, and P-selectin on the pulmonary vasculature for up to 7 days after I.T.-SRBC challenge. Neither the MECA 79 nor MECA 367 antigens were induced on the pulmonary vasculature during this period. In the peripheral blood, both CD4 and CD8 T-cell subsets showed an initial increase in P-selectin ligand expression after I.T.-SRBC challenge. The number of P-selectin ligand-positive T cells in the peripheral blood fell as T cells with both P-selectin and, to a lesser extent, E-selectin ligands accumulated in the bronchoalveolar lavage fluid. We conclude that I.T.-SRBC challenge in sensitized mice elicits prolonged synthesis of P-selectin, E-selectin, and VCAM-1 by the lung vasculature as well as selectin ligand synthesis by responding T cells. Furthermore, the entry of selectin-ligand-positive T cells into the circulation and their accumulation in the bronchoalveolar lavage fluid indicates that these receptors may contribute to T cell recruitment. Finally, VCAM-1 on the vasculature may also participate; however, the vascular addressins, required for homing to peripheral and mucosal lymphoid organs, are not essential for T-cell entry into the lung following I.T.-SRBC challenge.

Animals↗
PubMed1994

Room temperature stable perfluorocarbon emulsions with acceptable half-lives in the reticuloendothelial system.

Prolonged room temperature stability (i.e. zero particle growth) can be achieved for concentrated emulsions of perflubron (perfluorooctyl bromide) or perfluorodecalin via addition of a secondary high molecular weight, lipophilic fluorocarbon component. Due to their enhanced lipophilic character, the secondary fluorocarbon components have acceptable half-lives in the organs of the reticuloendothelial system.

Animals↗
PubMed1994

Proposed mechanism of pulmonary gas trapping (PGT) following intravenous perfluorocarbon emulsion administration.

PURPOSE: To investigate various hypotheses and identify the most likely mechanism preventing the complete collapse of test animal lungs at sacrifice subsequent to intravenous injection of certain perfluorocarbon emulsions. PROTOCOL: Literature data were reviewed, experimental data were extracted from completed studies and new data were generated in an attempt to delineate reasons why, in certain animals, lungs fail to collapse normally at necropsy if previously injected with certain perfluorocarbon emulsions. The proposed hypothesis involved gas osmosis through endogenous pulmonary surfactant-liquid bridges (micro-bubbles). RESULTS: The observed effect of incomplete lung collapse upon necropsy was found to correlate with perfluorocarbon vapor pressure. Results indicated that failure to collapse could be attributed to the formation of intra-alveolar micro-bubbles induced by the normal pulmonary elimination of perfluorocarbon vapor. These micro-bubbles result in a phenomenon which could be characterized by the term, pulmonary gas trapping. Reduction of the perfluorocarbon concentration gradient across the bubble films by exposure to a perfluorocarbon vapor-containing atmosphere was found to reduce the effect in-vivo and prevent gas osmosis bubble growth in-vitro. CONCLUSION: Experimental observations are consistent with the proposed theory of perfluorocarbon-related gas osmosis through micro-bubbles that prevent complete lung collapse as observed upon opening the thoracic cavity of test animals.

Animals↗
PubMed1987

Malignant evolution of penile horn.

We report a rare case involving evolution of a penile horn into a neoplastic lesion. This patient was treated with surgical excision and external radiation because of the invasive characteristics of the lesion.

Carcinoma, Squamous Cell↗
PubMed1983

Kinin formation in hereditary angioedema plasma: evidence against kinin derivation from C2 and in support of "spontaneous" formation of bradykinin.

Hereditary angioedema (HAE) is due to a functional deficiency of the inhibitor of the activated first component of complement (C1 INH). This abnormality is thought to be responsible for the generation of a kininlike peptide in HAE plasma that is derived from the second component of complement (C2). Specifically, a combination of C2 cleavage by C1s and C2 fragment cleavage by plasmin has been reported to generate a kinin that is distinguishable from bradykinin. We have attempted to generate this peptide by activating the classical complement pathway by incubation of plasma with immune complexes and then adding plasmin or by incubating purified C1s with C4 and C2 and then adding either plasmin or trypsin. We performed a total of 13 experiments, and in no case was a kininlike molecule generated as assessed by contraction of the estrus rat uterus. However, incubation of EDTA-treated HAE plasma at 37 degrees C for time intervals up to 1 hr progressively generated a smooth muscle-contracting activity. This activity was resistant to tryptic digestion but was destroyed after incubation with carboxypeptidase B, an inhibition profile consistent with that of bradykinin. We therefore propose that bradykinin alone, or in combination with other factors heretofore unrecognized, might be responsible for the swelling that is characteristic of hereditary angioedema.

Angioedema↗
PubMed1983

Breast radiography: phantom, equipment performance, and radiation dosage comparisons for twenty-eight major mammography centers in the midwest. Work in progress.

This preliminary report discusses mammography tests that were conducted at 28 midwest medical centers. Equipment-parameter measurements were made, and images that were obtained with the Stanton Mark IIR Mammography Phantom were studied to compare image quality. These tests indicate that variations in equipment parameters and techniques can result in differences in the imaging of various sized phantom fibril and speck groups.

Humans↗
PubMed1978

Improved cognition after external carotid endarterectomy.

Recent clinical results support the conclusion that internal carotid endarterectomy not only serves as a prophylactic measure against catastrophic stroke, but may improve cognitive functioning as well. Improvement in cognitive testing after internal carotid endarterectomy has been amply substantiated in recent literature. 3, 4, 5, 8, This report illustrates that improvement in cerebral blood flow by any means is equally effective in improving cerebral function.

Aged↗