Search PubMed⌕ Search

Biomedical subjects

E Wagner

Publications and source records attributed to E Wagner.

At least 55 records · Page 3Linked to original sources
PubMed2001

Retinoic acid synthesis for the developing telencephalon.

The small lipid retinoic acid is known to promote neuronal differentiation in vitro and to act as a teratogen in the embryonic brain, but very little is known about the natural role of endogenously synthesized retinoic acid in forebrain development. Retinoic acid is synthesized mainly by three retinaldehyde dehydrogenases. We show here where the retinaldehyde dehydrogenases for the developing telencephalon are expressed and how their expression patterns change over developmental time. Retinoic acid diffusing from the retinaldehyde dehydrogenase sites is likely to influence the early telencephalon before the beginning of neurogenesis, as well as differentiation and radial migration of neurons into the cerebral cortex. Because of its diffusible character, retinoic acid represents a unique tool for the coordination of growth processes over an intermediate distance range in the developing telencephalon.

Aldehyde Oxidoreductases↗
PubMed2001

Rescue of recombinant Thogoto virus from cloned cDNA.

Thogoto virus (THOV) is a tick-transmitted orthomyxovirus with a genome consisting of six negative-stranded RNA segments. To rescue a recombinant THOV, the viral structural proteins were produced from expression plasmids by means of a vaccinia virus expressing the T7 RNA polymerase. Genomic virus RNAs (vRNAs) were generated from plasmids under the control of the RNA polymerase I promoter. Using this system, we could efficiently recover recombinant THOV following transfection of 12 plasmids into 293T cells. To verify the recombinant nature of the rescued virus, specific genetic tags were introduced into two vRNA segments. The availability of this efficient reverse genetics system will allow us to address hitherto-unanswered questions regarding the biology of THOV by manipulating viral genes in the context of infectious virus.

Animals↗
PubMed2001

Preventing mediastinal shift after pneumonectomy impairs regenerative alveolar tissue growth.

To examine the effects of mechanical lung strain on regenerative growth of alveolar septal tissue after pneumonectomy (PNX), we replaced the right lungs of adult dogs with a custom-shaped inflatable silicone prosthesis. The prosthesis was either inflated (Inf) to maintain the mediastinum at the midline or deflated to allow mediastinal shift. The animals were euthanized approximately 15 mo later, and the lungs were fixed at a constant distending pressure. With the Inf prostheses, lung expansion, alveolar septal tissue volumes, surface areas, and diffusing capacity of the tissue-plasma barrier were significantly lower than with the deflated prostheses; the expected post-PNX tissue responses were impaired by 30-60%. Capillary blood volume was significantly higher with Inf prostheses, consistent with microvascular congestion. Measurements in the Inf group remained consistently and significantly higher than those expected for a normal left lung, indicating persistence of partial compensation. In one dog, delayed deflation of the prosthesis 9-10 mo after PNX led to vigorous lung expansion and septal tissue growth, particularly of type II epithelial cells. We conclude that mechanical lung strain is a major signal for regenerative lung growth; however, other signals are also implicated, accounting for a significant fraction of the compensatory response to PNX.

Animals↗
PubMed2001

DNA/polyethylenimine transfection particles: influence of ligands, polymer size, and PEGylation on internalization and gene expression.

Receptor-binding ligands have been incorporated into DNA/polyethylenimine (PEI) complexes to enhance cell binding and cellular internalization. This study characterizes receptor-mediated uptake of DNA/PEI complexes on a cellular basis. A novel assay based on flow cytometry was applied, discriminating between total cell-associated and extracellularly bound DNA complexes. Receptor-mediated uptake of ligand-containing DNA/PEI (molecular weight, 800 kd) complexes was found to occur quickly (within 1 hour), whereas unspecific uptake through adsorptive endocytosis is less efficient or requires extended periods to reach the same degree of internalization. Rapid, receptor-mediated internalization requires a small complex size; however, large, aggregated complexes show higher gene expression. Using PEI 25 kd conjugated to large proteins such as transferrin or antibodies, improper condensation with DNA leads to suboptimal uptake and gene expression, whereas partial replacement of ligand-PEI with unconjugated PEI increases both uptake and transfection. In contrast, the 8 kd protein epidermal growth factor conjugated to PEI 25 kd properly condenses DNA and mediates specific uptake into human adenocarcinoma (KB) cells. Modification of the complex surface with appropriate amounts of poly(ethylene glycol) (PEG) does not block ligand-mediated internalization. A higher degree of PEGylation reduces the internalization of transferrin or antibody-containing complexes to a level similar to that of ligand-free complexes. In contrast, epidermal growth factor "mediated uptake is less effected by excessive PEGylation.

DNA↗
PubMed2001

Prey detection in selective plankton feeding by the paddlefish: is the electric sense sufficient?

The long rostrum of the paddlefish Polyodon spathula supports an extensive array of ampullary electroreceptors and has been proposed to function as an antenna for detecting planktonic prey. Evidence in support of this hypothesis is presented in experiments that preclude the use of other sensory mechanisms for plankton detection. Paddlefish swimming in a recirculating observation chamber are shown to feed normally in the dark when prey-related chemical and hydrodynamic sensory cues are masked or attenuated. Specifically, we demonstrate that the spatial distribution of plankton captured by paddlefish is little changed when the plankton are individually encapsulated in agarose, when a high background concentration of plankton extract is added to the chamber, when the nares are plugged and under turbulent water flow conditions. Paddlefish also discriminate between encapsulated plankton and 'empty' agarose particles of the same size. Although capture distributions differed somewhat under certain conditions, the general pattern and effectiveness of prey capture were not disrupted by these procedures. These results support the conclusion that paddlefish, as zooplanktivores, rely on their passive electric sense for prey detection.

Animals↗
PubMed2001

The effect of neighborhood-based community organizing: results from the Seattle Minority Youth Health Project.

OBJECTIVE: To evaluate the effect of a community mobilization and youth development strategy to prevent drug abuse, violence, and risky sexual activity. DATA SOURCES/STUDY SETTING: Primary surveys of youth, parents, and key neighborhood leaders were carried out at baseline (1994) and at the end of the intervention period (1997). The study took place in four intervention and six control neighborhoods in Seattle. STUDY DESIGN: The study was designed as a randomized controlled trial with neighborhood as the unit of randomization. The intervention consisted of a paid community organizer in each neighborhood who recruited a group of residents to serve as a community action board. Key variables included perceptions of neighborhood mobilization by youth, parents, and key neighborhood leaders. DATA COLLECTION/EXTRACTION METHODS: Youth surveys were self-administered during school hours. Parent and neighborhood leader surveys were conducted over the phone by trained interviewers. PRINCIPAL FINDINGS: Survey results showed that mobilization increased to the same degree in both intervention and control neighborhoods with no evidence of an overall intervention effect. There did appear to be a relative increase in mobilization in the neighborhood with the highest level of intervention activity. CONCLUSION: This randomized study failed to demonstrate a measurable effect for a community mobilization intervention. It is uncertain whether the negative finding was because of a lack of strength of the interventions or problems detecting intervention effects using individual-level closed-end surveys.

Adolescent↗
PubMed2001

Measuring clinical performance: comparison and validity of telephone survey and administrative data.

OBJECTIVE: To compare and validate self-reported telephone survey and administrative data for two Health Plan Employer Data and Information Set (HEDIS) performance measures: mammography and diabetic retinal exams. DATA SOURCES/STUDY SETTING: A telephone survey was administered to approximately 700 women and 600 persons with diabetes randomly chosen from each of two health maintenance organizations (HMOs). STUDY DESIGN: Agreement of survey and administrative data was assessed by using kappa coefficients. Validity measures were assessed by comparing survey and administrative data results to a standard: when the two sources agreed, that was accepted as the standard; when they differed, confirmatory information was sought from medical records to establish the standard. When confirmatory information was not available ranges of estimates consistent with the data were constructed by first assuming that all persons for whom no information was available had received the service and alternately that they had not received the service. PRINCIPAL FINDINGS: The kappas for mammography were .65 at both HMOs; for retinal exam they were .38 and .40. Sensitivity for both data sources was consistently high. However, specificity was lower for survey (range .44 to .66) than administrative data (.99 to 1.00). The positive predictive value was high for mammography using either data source but differed for retinal exam (survey .69 to .78; administrative data .99 to 1.00). CONCLUSIONS: Administrative and survey data performed consistently in both HMOs. Although administrative data appeared to have greater specificity than survey data the validity and utility of different data sources for performance measurement have only begun to be explored.

Adult↗
PubMed2000

Xenogenization by tetanus toxoid loading into lymphoblastoid cell lines and primary human tumor cells mediated by polycations and liposomes.

We explored the potential of the xenogenization concept as an adjuvant procedure in anti-tumor immunity. To mediate effective loading we used polyarginine (pArg) molecules of various degrees of polymerization, cationic liposomes, or chimeric molecules of transferrin (Tf) and the polycation polyethyleneimine (PEI). Tetanus toxoid (TT) was loaded onto primary human leukemia cells, culture adapted primary human neuroblastoma cells, and human lymphoblastoid cell lines (LCLs) with high efficiency by all procedures. Trypsin treatment of loaded cells provided evidence that only liposomes and Tf-PEI mediated internalization of TT. Lymphocytes primed with xenogenized LCLs and challenged with unmodified LCLs showed increased IFNgamma secretion compared with lymphocytes primed with non-xenogenized LCLs.

B-Lymphocytes↗
PubMed2000

Development of a multichannel fluorescence affinity sensor system

A multichannel fluorometer is proposed for analysis of biochemical reactions. The sensor is based on the luminescence generation in the evanescent field of a totally reflected laser beam. For transduction, multiple reflection elements are used. Multichannel operation is realized, including the possibility of applying different solutions to each channel at the same time. First experimental results, obtained with fluorescein or Cy5 as labels in a model hybridization assay, demonstrate the applicability and allow the detection of 3-10 fmol injected fluorescently labeled oligonucleotide.

Journal Article↗
PubMed2000

Retinoic acid in the formation of the dorsoventral retina and its central projections.

Dynamic expression patterns of four retinoid-metabolizing enzymes create rapidly changing retinoic acid (RA) patterns in the emerging eye anlage of the mouse. First, a RA-rich ventral zone is set up, then a RA-poor dorsal zone, and finally a tripartite organization consisting of dorsal and ventral RA-rich zones separated by a horizontal RA-poor stripe. This subdivision of the retina into three RA concentration zones is directly visible as beta-galactosidase labeling patterns in retinas of RA-reporter mice. Because the axons of retinal ganglion cells transport the reporter product anterogradely, the central projections from dorsal and ventral retina can be visualized as two heavily labeled axon bundles. Comparisons of the axonal labeling with physiologic recordings of visual topography in the adult mouse show that the labeled axons represent the upper and the lower visual fields. The RA-poor stripe develops into a broad horizontal zone of higher visual acuity. Comparisons of the retina labeling with eye-muscle insertions show that the axis of the RA pattern lines up with the dorsoventral axis of the oculomotor system. These observations indicate that the dorsoventral axis of the embryonic eye anlage determines the functional coordinates of both vision and eye movements in the adult.

Aldehyde Dehydrogenase↗
PubMed2000

Gestational age-dependent expression of IL-10 and its receptor in human placental tissues and isolated cytotrophoblasts.

Control of antifetal immune responses is thought to be regulated locally by the placenta. Because the physiologic programming of the placenta across gestation is likely to influence the local immunity, we hypothesize that a potent anti-inflammatory cytokine such as IL-10 may be produced in a gestational age-dependent manner. In the present study, we examined the expression of IL-10 and its receptor in placental explants or freshly isolated cytotrophoblasts from different gestational ages and compared it with the expression profiles of other cytokines. First and second trimester placental tissues from normal pregnancies predominantly expressed IL-10, whereas the levels of IL-2, IL-4, and IFN-gamma were mostly below detection throughout pregnancy. The expression of IL-10, but not its receptor, diminished significantly in term placental tissues collected "before" the onset of labor and did not change appreciably "after" labor. On the other hand, TNF-alpha and IL-1beta were significantly up-regulated in response to labor-associated conditions. IL-10 expression was transcriptionally attenuated at term as observed in cytotrophoblasts. In contrast to the placental cytokine milieu, autologous PBMCs, when activated with PHA, secreted significant amounts of IL-2, IL-4, IL-10, and IFN-gamma, albeit with a statistically significantly enhanced IL-10 production in first trimester compared with age-matched nonpregnant women. These data suggest that IL-10 is expressed in the placenta in a gestational age-dependent manner and that its down-regulation at term may be an important mechanism underlying the subtle changes associated with parturition.

Adolescent↗
PubMed2000

A versatile assay to study cellular uptake of gene transfer complexes by flow cytometry.

In this study, we present a simple and reliable method to analyse the first steps of DNA-based gene delivery into eucaryotic cells, i. e. binding and internalisation of transfection complexes. Taking advantage of flow cytometry, it is possible to discriminate quantitatively between total and internal DNA on a single-cell level. Here, we use two fluorescent dyes with high specificity and affinity to double-stranded DNA that cannot penetrate the extracellular membrane of living cells. Total DNA is stained prior to complexation with the first dye and complexes are added to cells. After the incubation, only extracellular DNA remains accessible to the second dye. Cell associated fluorescence is measured simultaneously using a flow cytometer and data are analysed using a computer program capable of calculating the ratio of fluorescence intensities on a single-cell level. These ratios are indicative of the binding and internalisation kinetics of gene transfer complexes.

Cell Adhesion↗
PubMed2000

Metabolism and function of 3-D-phosphorylated phosphoinositides in C5a-stimulated eosinophils.

Eosinophils play a central role in the pathogenesis of parasitic infections, atopic diseases, and bullous dermatoses. To understand the regulative function of phosphatidylinositol 3-kinases in cell responses of eosinophils, phospholipid metabolism and production of reactive oxygen metabolites were followed after stimulation with C5a. Measurements of phosphatidylinositol lipids and analysis of deacylated products of separated lipid extracts showed fast and transient formation of phosphatidylinositol 3,4,5-trisphosphate (PIP(3)). Cell studies in the presence of the tyrosine kinase blocker genistein indicated that C5a-stimulated PIP(3) formation occurred independently of tyrosine kinase activity. To analyze the function of PI4,5P(2)-3-kinase in eosinophils, the influence of wortmannin and LY294002 on production of reactive oxygen metabolites was studied. Both compounds inhibited with similar concentration dependency C5a-induced formation of PIP(3) and production of reactive oxygen metabolites. In summary, these data showed for the first time the involvement of PI4,5P(2)-3-kinase in the production of reactive oxygen metabolites in eosinophils.

Androstadienes↗
PubMed2000

Randomised trial of monitoring, feedback, and management of care by telephone to improve treatment of depression in primary care.

OBJECTIVE: To test the effectiveness of two programmes to improve the treatment of acute depression in primary care. DESIGN: Randomised trial. SETTING: Primary care clinics in Seattle. PATIENTS: 613 patients starting antidepressant treatment. INTERVENTION: Patients were randomly assigned to continued usual care or one of two interventions: feedback only and feedback plus care management. Feedback only comprised feedback and algorithm based recommendations to doctors on the basis of data from computerised records of pharmacy and visits. Feedback plus care management included systematic follow up by telephone, sophisticated treatment recommendations, and practice support by a care manager. MAIN OUTCOME MEASURES: Blinded interviews by telephone 3 and 6 months after the initial prescription included a 20 item depression scale from the Hopkins symptom checklist and the structured clinical interview for the current DSM-IV depression module. Visits, antidepressant prescriptions, and overall use of health care were assessed from computerised records. RESULTS: Compared with usual care, feedback only had no significant effect on treatment received or patient outcomes. Patients receiving feedback plus care management had a higher probability of both receiving at least moderate doses of antidepressants (odds ratio 1.99, 95% confidence interval 1.23 to 3.22) and a 50% improvement in depression scores on the symptom checklist (2.22, 1.31 to 3.75), lower mean depression scores on the symptom checklist at follow up, and a lower probability of major depression at follow up (0.46, 0.24 to 0.86). The incremental cost of feedback plus care management was about $80 ( pound50) per patient. CONCLUSIONS: Monitoring and feedback to doctors yielded no significant benefits for patients in primary care starting antidepressant treatment. A programme of systematic follow up and care management by telephone, however, significantly improved outcomes at modest cost.

Acute Disease↗
PubMed2000

Purification and characterization of an aminopeptidase from the chloroplast stroma of barley leaves by chromatographic and electrophoretic methods.

Aminopeptidases catalyze the cleavage of amino acids from the amino terminus of protein or peptide substrates. Although some aminopeptidase activities have been found in plant chloroplasts, the identity of these proteins remains unclear. In this work, we report the purification to apparent homogeneity of a soluble aminopeptidase from isolated barley chloroplasts which preferentially degraded alanyl-p-nitroanilide (Ala-pNA). After organelle isolation in a density gradient and precipitation of soluble proteins with ammonium sulfate, the proteins were purified in three consecutive steps including hydrophobic interaction, gel permeation and ion-exchange chromatographies. The purified enzyme appeared as a single band with a Mr of approximately 84000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The Mr of the native enzyme was estimated to be approximately 93000 by gel permeation chromatography, suggesting that the protein is a monomer. Mass spectrometry analysis of tryptic digests indicates that the primary structure of the protein has not been reported previously. The enzyme was characterized as a metalloprotease as it could be totally inhibited by 1,10-phenanthroline. Strong inhibition could also be observed using the specific aminopeptidase inhibitors amastatin and bestatin. Besides Ala-pNA, the purified protein could also cleave with decreasing activity glycyl-pNA, leucyl-pNA, lysyl-pNA, methionyl-pNA and arginyl-pNA. The possible physiological role of this enzyme in the chloroplast stroma is discussed.

Aminopeptidases↗
PubMed2000

Specific detection of membrane-toxic substances with a conductivity assay.

A conductivity assay that represents a new biotest able to detect the effects of membrane-toxic compounds, e.g., detergents, organic solvents, and radical formers, on various organisms was previously described and developed. The conductivity assay measures ion leakage from cells, tissues, or whole plant and animal organisms whose membrane systems have been damaged by membrane-toxic compounds. In this study the specificity of the conductivity assay for membrane-toxic compounds was tested by comparing the electrolyte efflux from Elodea canadensis leaves during incubation with a well-known detergent (benzalkonium chloride) using different plant physiological and biochemical techniques (photochemical efficiency, plasmolysis capacity, NBT reduction, and electron microscopy of membranes of E. canadensis leaves). The comparison of the different methods proved that the electrolyte loss during benzalkonium chloride incubation determined in the conductivity assay is due to membrane impairment. The observed electrolyte loss correlated with a reduction of photochemical efficiency and a decrease in both plasmolysis and NBT reduction capacity. Furthermore, a disintegration of the plasmalemma could be seen in the electron micrographs. These results indicate that the measured electrolyte loss in the conductivity assay is a specific effect of membrane-toxic compounds.

Benzalkonium Compounds↗
PubMed2000

Angiogenesis in the mouse lung.

When pulmonary arterial blood flow is obstructed in all mammals studied, there is a compensatory growth of the bronchial vasculature. This angiogenesis normally occurs through a proliferation of the systemic circulation to the intraparenchymal airways. It is an important pathophysiological process, not only in pulmonary vascular disease, but also in lung cancer, because the blood flow that supplies primary lung tumors arises from the systemic circulation. In the mouse, however, the systemic blood vessels that supply the trachea and mainstem bronchi do not penetrate into the intraparenchymal airways, as they do in all other larger species. In this study, we attempted to generate a new functional bronchial circulation in the mouse by permanently obstructing 40% of the pulmonary circulation. We quantified the systemic blood flow to the lung with fluorescent microspheres for 3 months after left pulmonary artery ligation. Results demonstrated that a substantial systemic blood flow to the lung that can eventually supply up to 15% of the normal pulmonary flow can be generated beginning 5-6 days after ligation. These new angiogenic vessels do not arise from the extraparenchymal bronchial circulation. Rather they enter the lung directly via a totally new vasculature that develops between the visceral and parietal pleuras, supplied by several intercostal arteries. This unique model of angiogenesis occurs in the absence of any hypoxic stimulus and mimics the vascular source of many lung tumors.

Airway Resistance↗