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Biomedical subjects

E Wagner

Publications and source records attributed to E Wagner.

At least 181 records · Page 10Linked to original sources
PubMed1994

Differences in sociodemographic, health status, and lifestyle characteristics among American Indians by telephone coverage.

BACKGROUND: Telephone interviews are often used to obtain population-based estimates of health-related behaviors but they have serious limitations if phone coverage is poor and people without telephones differ from those with telephones. In this article we examine differences in selected sociodemographic, health status, and lifestyle factors among a sample of American Indian adults with and without telephones. METHODS: In-person interviews were conducted with 410 adult residents of a Rocky Mountain state American Indian reservation. The interview included a question asking about telephone coverage. We compared respondents with and without telephones on demographics, health status, and lifestyle practices. The comparison was repeated for health status and lifestyle practices after adjusting for differences in demographic characteristics. RESULTS: Residents without phones generally were less educated, had lower income and were more likely to be unemployed. The prevalence of unhealthful lifestyle practices/factors was consistently higher for residents without telephones. Many of the differences were reduced by adjusting for demographic characteristics, but significant differences remained for alcohol and marijuana use. CONCLUSIONS: These results suggest that developing estimates of sociodemographic, health, and lifestyle characteristics on a Native American Indian reservation using a telephone survey method may result in significant noncoverage biases. Adjusting for demographic characteristics eliminated most of these differences. However, significant differences were still apparent with alcohol and marijuana use.

Adolescent↗
PubMed1994

Efficient foreign gene expression in Epstein-Barr virus-transformed human B-cells.

Epstein-Barr virus (EBV) is a herpesvirus that transforms B-cells (B-LCL) and has undergone intense scrutiny owing to its association with Burkitt's lymphoma, nasopharyngeal carcinoma, and immunoblastic lymphomas. B-LCL have also proven useful in the study of human immunology. We describe a novel system for inducing efficient foreign gene expression in B-LCL using biotinylated adenovirus as an endosome-disrupting agent. Plasmid DNA is coupled to the exterior of viral particles by streptavidin-polylysine chimeric proteins. Up to 67% of B-LCL may be induced to express foreign genes in vitro in transient expression systems, and gene expression lasts for at least 17 days. We have expressed firefly luciferase, beta-galactosidase (beta-gal), chloramphenicol acetyltransferase, HIV gag, and env genes, as well as infectious HIV, and the EBV-specific BZLF gene in B-LCL with this system. In vivo delivery of a beta-gal reporter gene to B-LCL was documented in a SCID mouse model. Potential applications include study of genetic regulation of EBV infection and transformation events, study of potential gene therapies for EBV-related B-cell tumors, and production of antigen-presenting cells for use in immunologic assays. Because of the high percentage of cells transformed and the length of foreign gene expression, the possibility of examining foreign gene expression in transient assays, without selection for clonal populations, exists.

Animals↗
PubMed1994

Synthesis and anti-HIV activity of thiocholesteryl-coupled phosphodiester antisense oligonucleotides incorporated into immunoliposomes.

Encapsulation of oligonucleotides in antibody-targeted liposomes (immunoliposomes) which bind to target cells permits intracellular delivery of the oligonucleotides. This approach circumvents problems of extracellular degradation by nucleases and poor membrane permeability which free phosphodiester oligonucleotides are subject to, but leaves unresolved the inefficiency of encapsulation of oligonucleotides in liposomes. We have coupled oligonucleotides to cholesterol via a reversible disulfide bond. This modification of oligonucleotides improved their association with immunoliposomes by a factor of about 10 in comparison to unmodified oligonucleotides. The presence of cholesteryl-modified oligonucleotides incorporated in the bilayer of liposomes did not interfere with the coupling of the targeting protein to the liposome surface. Free or cholesterol coupled oligonucleotides associated with liposomes and directed against the tat gene of HIV-1 were tested for inhibition of HIV-1 proliferation in acutely infected cells. We demonstrate that the cholesteryl-modified as well as unmodified oligonucleotides acquire the target specificity of the antibody on the liposome. Their antiviral activity when delivered into cells is sequence-specific. The activity of these modified or unmodified oligonucleotides to inhibit the replication of HIV was the same on an equimolar basis (EC50 around 0.1 microM). Cholesterol coupled oligonucleotides thus offer increased liposome association without loss of antiviral activity.

Antibodies↗
PubMed1994

Gene therapy for B-cell lymphoma in a SCID mouse model using an immunoglobulin-regulated diphtheria toxin gene delivered by a novel adenovirus-polylysine conjugate.

Despite advances in conventional therapy, many lives continue to be lost to common forms of B-cell cancers, including leukemias, lymphomas and multiple myeloma. We propose a novel approach to therapy of such cancers using controlled expression of a diphtheria toxin gene (DT-A) to kill malignant cells. We have previously demonstrated selective killing of various cell types, in vitro and in vivo, by cell-specific, transcriptionally controlled expression of this gene. Organ-specific ablation in otherwise healthy transgenic mice has convincingly demonstrated the exquisite specificity achievable by this technique. In the studies now described, DT-A was delivered in vitro and in vivo using a novel gene delivery system employing DNA physically attached to the exterior of adenovirus. After demonstrating the efficacy of gene delivery to Epstein-Barr virus transformed human B-cells in vitro, in vivo work was performed using a SCID mouse model for B-cell lymphoma, in which protection against tumor was observed. The concepts of tissue-regulated toxin gene therapy, and this novel adenovirus gene delivery system are discussed.

Adenoviridae↗
PubMed1994

Carbohydrate receptor-mediated gene transfer to human T leukaemic cells.

The mucin-type carbohydrate Tn cryptantigen (GalNAc alpha 1-O-Ser/Thr, where GalNAc is N-acetyl-D-galactosamine) is expressed in many carcinomas, in haemopoietic disorders including the Tn syndrome, and on human immunodeficiency virus (HIV) coat glycoproteins, but is not expressed on normal, differentiated cells because of the expression of a Tn-processing galactosyltransferase. Using Jurkat T leukaemic cells which express high levels of Tn antigen due to deficient Tn galactosylation, we have established the Tn antigen-mediated gene transfer and demonstrate the considerable efficiency of this approach. We used poly(L-lysine) conjugates of the monoclonal antibody 1E3 directed against the Tn antigen to deliver the luciferase and beta-galactosidase reporter genes to Jurkat cells by receptor-mediated endocytosis. Addition of unconjugated 1E3 reduced transfection efficiency in a concentration-dependent manner and incubation with free GalNAc abolished DNA transfer completely, indicating that gene delivery is indeed mediated by the Tn antigen. Pre-treatment of Jurkat cells with Vibrio cholerae sialidase, which uncovers additional Tn antigens, resulted in an improvement of gene transfection. Both human and chicken adenovirus particles attached to the DNA/polylysine complex strongly augmented transgene expression. When the beta-galactosidase (lacZ) gene was delivered to Jurkat cells by Tn-mediated endocytosis, up to 60% of the cells were positive in the cytochemical stain using 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) as a chromogenic substrate. The efficiency of the transferrin receptor-mediated DNA uptake into Jurkat cells was comparatively low, although these cells were shown to express considerable amounts of transferrin receptor. We show here that a mucin-type carbohydrate antigen mediates highly efficient DNA uptake by endocytosis into Jurkat T cells. This method represents a 50-fold improvement of Jurkat cell transfection efficiency over other physical gene transfer techniques. Specific gene delivery to primary cancer cells exhibiting Tn epitopes may especially be desirable in immunotherapy protocols.

Adenoviridae↗
PubMed1994

Genetic modification of cells by receptor-mediated adenovirus-augmented gene delivery: a new approach for immunotherapy of cancer.

Most concepts of gene therapy of cancer are based on the generation of an enhanced immune response against the cancer by means of vaccination with gene-modified cancer cells. We have investigated the applicability of a new gene transfer technique which uses the receptor-mediated endocytosis pathway and the endosome disruption activity of adenovirus for the generation of a cancer vaccine consisting of interleukin-2 (IL-2)-transfected, irradiated murine melanoma cells (clone M-3). This technique resulted in very high IL-2 expression (in the range of 30,000 Units IL-2/10(6) cells/24 hrs) in the transfected cells without the need to selection of stably expressing cell clones. We found that this high IL-2 expression of the melanoma cells correlates with high efficacy of the vaccine. Immunization of animals with this vaccine elicits a systemic T-cell-mediated immune response which protects from tumor development after implantation of highly tumorigenic doses of wild-type melanoma cells.

Adenoviridae↗
PubMed1994

Lipopolysaccharide is a frequent contaminant of plasmid DNA preparations and can be toxic to primary human cells in the presence of adenovirus.

Endotoxin (lipopolysaccharide, LPS) is commonly found as a contaminant in plasmid DNA preparations. We demonstrate here that the quantities of LPS typically contaminating DNA preparations can generate a toxicity to primary cells (primary human skin fibroblasts, primary human melanoma cells) in the presence of entry-competent adenovirus particles. Toxicity can be observed with as little as 100 ng/ml free LPS or 100 pg/ml LPS when the LPS is assembled into polylysine/adenovirus complexes. Simple and effective methods of removing the contaminating LPS using either a polymyxin B resin or Triton X-114 extraction are described. Treatment of DNA samples to remove LPS eliminates the toxicity to primary cells.

Adenoviridae↗
PubMed1994

Receptor-mediated gene delivery employing lectin-binding specificity.

Selective targeting of malignant cells will be necessary to implement many of the gene therapy strategies being designed to combat cancer. Targeting can be achieved by transductional or transcriptional approaches. Transductional targeting can be accomplished by exploiting differences in the molecules or receptors expressed on the cell surface of malignant versus normal cells. Given that malignant cells can be distinguished from normal by differences in the expression of cell surface carbohydrates, we hypothesized that transductional targeting would be feasible by molecular conjugate vectors which achieve cell binding by virtue of lectins directed against the cell surface glycocalyx. We have shown that gene transfer can be accomplished by these novel lectin-targeted molecular conjugate vectors and that lectin binding specificities may serve as a means for potential targeting of cancer cells for the purposes of gene therapy.

Animals↗
PubMed1994

Age-related changes in cortical blood flow activation during visual processing of faces and location.

We examined age-related changes in object and spatial visual processing in two separate experiments. Regional cerebral blood flow (rCBF) was measured in young and old subjects with positron emission tomography and H2(15)O during tests of face matching, location matching, and a control task. The task demands in the two experiments were identical, but the stimuli in Experiment II were constructed to equalize stimulus complexity across all three tasks. The old subjects performed more slowly than the young subjects in both experiments, and showed significantly slower reaction times during location matching compared to face matching in Experiment II. Both young and old subjects showed occipitotemporal rCBF activation during face matching and occipitoparietal activation during location matching when these conditions were compared to the control task. However, in both experiments and in both tasks, young subjects showed greater activation of prestriate cortex (Brodmann's area 18), and old subjects had larger rCBF increases in occipitotemporal cortex (area 37). Areas in prefrontal cortex, as well as in inferior and medial parietal cortex, were more activated in the old subjects during location matching in both experiments. These results demonstrate that reliable age-related changes during visual processing can be found in rCBF patterns, suggesting more efficient use of occipital visual areas by younger subjects and more reliance by older subjects on one or more cortical networks, particularly for spatial vision, perhaps to compensate for reduced processing efficiency of occipital cortex. Both the differentially increased reaction times and the more widespread prefrontal activation in the old subjects during location matching suggest that spatial vision may be affected to a greater degree by aging than is object vision.

Adult↗
PubMed1994

[Prognostic criteria for initial success in PTA and catheter thrombolysis].

The preliminary results of 1063 percutaneous dilatations (PTA) of iliac or femoropopliteal arteries were evaluated in order to establish pre-existing clinical or morphological criteria with possible influence on the early success rate. Early failure was defined as the impossibility to eliminate the arterial occlusion or re-occlusion within 48 hours. Regarding the clinical criteria the combination of long duration and advanced stage of the disease unfavourably influenced the primary success rate (failure rate of 40%). Morphological factors such as length of occlusion over 10 cm, poor run-off or existence of large arterio-venous shunts had an even worse influence on the early success rate (failure rate of 50-60%).

Angiography, Digital Subtraction↗
PubMed1993

Somatic gene therapy for cancer: the utility of transferrinfection in generating 'tumor vaccines'.

The last few years have seen the development of a branch of somatic gene therapy which aims at strengthening the immune surveillance of the body, leading to eradication of disseminated cancer tumor cells and occult micrometastases after surgical removal of the primary tumor. Such a tumor vaccination protocol calls for cultivation of the primary tumor tissue and the insertion of one of three types of genes into the isolated cultured tumor cells followed by irradiation of the transfected or transduced cells to render them incapable of further proliferation. The cells so treated constitute the 'tumor vaccine'. A review of the literature suggests that for mouse models, in the initial period after inoculation, rejection of the tumor cells is usually effected by non-T-cell immunity, whereas the long-term systemic immune response is based on cytotoxic T-cells. High expression of the gene inserted into the tumor cells may be critical for the success of the vaccination procedure. Examples are given which indicate that transferrinfection, a procedure to introduce genes by adenovirus-augmented receptor-mediated endocytosis, meets some important prerequisites for successful application of this type of gene therapy.

Animals↗
PubMed1993

Binding-incompetent adenovirus facilitates molecular conjugate-mediated gene transfer by the receptor-mediated endocytosis pathway.

Molecular conjugate vectors may be constructed that accomplish high efficiency gene transfer by the receptor-mediated endocytosis pathway. In order to mediate escape from lysosomal degradation, we have incorporated adenoviruses into the functional design of the conjugate. In doing so, however, we have introduced an additional ligand, which can bind to receptors on the cell surface, undermining the potential for cell specific targeting. To overcome this, we have treated the adenovirus with a monoclonal anti-fiber antibody, which renders the virus incapable of binding to its receptor. The result is a multi-functional molecular conjugate vector, which has preserved its binding specificity while at the same time being capable of preventing lysosomal degradation of endosome-internalized conjugate-DNA complexes. This finding indicates that adenoviral binding is not a prerequisite for adenoviral-mediated endosome disruption.

Adenoviruses, Simian↗
PubMed1993

Gene structure and expression analysis of the epidermal growth factor receptor, transforming growth factor-alpha, myc, jun, and metallothionein in human ovarian carcinomas. Classification of malignant phenotypes.

This study reports the structure and expression rates of genes of the transforming growth factor-alpha (TGF-alpha) signal transduction pathway (TGF-alpha, epidermal growth factor receptor [EGF-R], jun, myc, and metallothionein [MT]) in 47 specimens of ovarian cancer and 21 nonmalignant tissues. The objective was to establish a direct correlation between the genetic activities and the malignant phenotype of the ovarian cancer. The Southern blot technique identified four samples with myc amplification and two with rearranged EGF-R genes. By using the S1 nuclease assay, the analysis of myc transcription showed a similar use of both promotors. Although the size of the investigated transcripts was unaltered, significant differences in the transcription rates were noticed in malignant tissue probes (using northern blot analysis and RNAase protection assay). The following results of messenger RNA analysis in ovarian cancer were observed: EGF-R, negative in 25%, low in 65%, and strongly positive in 10%; TGF-alpha, negative in 34%, low in 36%, and strongly positive in 30%; myc, negative in 8%, low in 64%, and strongly positive in 28%; jun, negative in 4%, low in 58%, and strong in 38%; and MT, low in 80% and strongly positive in 20%. In most nonmalignant tissues studied, no or only a low expression of TGF-alpha, EGF-R, and myc. was found. A comparison of these messenger RNA results with the clinical data from tumors showed four different subgroups of ovarian carcinomas. The results of chemotherapy were known in 32 cases. Tumors with negative or low expression rates of all investigated genes did not respond to chemotherapy; 13 of 18 tumors with high expression rates did respond. Additional signal transduction chains distinct from the TGF-alpha pathway, however, are likely to influence both the expression and activity of transcription factors and MT.

Adult↗
PubMed1993

The marketplace in health care reform. The demographic limitations of managed competition.

BACKGROUND: The theory of managed competition holds that the quality and economy of health care delivery will improve if independent provider groups compete for consumers. In sparsely populated areas where relatively few providers are required, however, it is not feasible to divide the provider community into competing groups. We examined the demographic features of health markets in the United States to see what proportion of the population lives in areas that might successfully support managed competition. METHODS: The ratios of physicians to enrollees in large staff-model health maintenance organizations were determined as an indicator of the staffing needs of an efficient health plan. These ratios were used to estimate the populations necessary to support health organizations with various ranges of specialty services. Metropolitan areas with populations large enough to support managed competition were identified. RESULTS: We estimated that a health care services market with a population of 1.2 million could support three fully independent plans. A population of 360,000 could support three plans that independently provided most acute care hospital services, but the plans would need to share hospital facilities and contract for tertiary services. A population of 180,000 could support three plans that provided primary care and many basic specialty services but that shared inpatient cardiology and urology services. Health markets with populations greater than 180,000 would include 71 percent of the U.S. population; those with populations greater than 360,000, 63 percent; and those with populations greater than 1.2 million, 42 percent. CONCLUSIONS: Reform of the U.S. health care system through expansion of managed competition is feasible in medium-sized or large metropolitan areas. Smaller metropolitan areas and rural areas would require alternative forms of organization and regulation of health care providers in order to improve quality and economy.

Adolescent↗