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Biomedical subjects

C Steiner

Publications and source records attributed to C Steiner.

At least 37 records · Page 2Linked to original sources
PubMed1996

Georgia's harvesting healthy habits: a formative evaluation.

Occupational safety and health researchers seek to conduct effective cancer awareness campaigns to increase agricultural workers' skin cancer prevention and detection behaviors. Georgia undertook such a project using a social cognitive theory (Bandura, 1986) conceptual model, with its objectives focusing on personal determinants of and environmental influences on farmers' behavior. One underused strategy to increase the success of health campaigns, formative evaluation, was undertaken during year one of the demonstration project, with four goals. These included an assessment of: (1) the availability of societal resources to support farmers' practices, (2) the affordability for farmers to follow through with behaviors being promoted, (3) the social support for behaving in ways that reduce farmers' skin cancer risk, and (4) farmers' current knowledge, outcome expectations, and self-efficacy in this regard. Formative evaluation revealed an absence of information, products, services, and social support for farmers' skin cancer prevention and detection. As a result, the Georgia project's plan was refined to include specific activities aimed at increasing the environmental support for health promotion activities relating to farmers' skin cancer prevention and detection. These include a seminar for rural primary care physicians and public health nurses to increase knowledge and skills relating to conducting clinical skin exams; programs for agricultural extension agents, cotton scouts, and 4-H groups to provide opportunities to learn more about and practice sun safety; and a feed and seed store campaign.

Agriculture↗
PubMed1995

Acute rejection of vascular heart allografts by perforin-deficient mice.

To study the role of perforin in cell-mediated graft rejection, vascularized hearts were grafted to perforin-deficient C57BL/6 and control C57BL/6 recipient mice. Fully allogeneic heart grafts (BALB/c) were acutely rejected by both recipients within 6 days. Peritoneal exudate lymphocytes from control mice but not from perforin-deficient mice exhibit a strong alloreactive cytotoxic activity in vitro. Histological analysis of the rejected tissues demonstrated extensive mononuclear cell infiltrates in both recipients. Flow cytometry analysis and immunohistology of graft-infiltrating cells showed similar proportions of lymphocyte subsets (CD8 >> CD4). Collectively, these data indicate that perforin is not essential in the cell-mediated acute rejection of a fully mismatched heart allograft. However, perforin-dependent effector mechanisms appeared to be limiting in the T cell-mediated rejection of heart allografts differing only at a single major histocompatibility complex class I antigen (bm1), because these grafts survived longer (mean 87.8 days) in perforin-deficient than in control mice (mean 31.5 days).

Animals↗
PubMed1994

The immunosuppressant rapamycin blocks in vitro responses to hematopoietic cytokines and inhibits recovering but not steady-state hematopoiesis in vivo.

The immunosuppressive drug rapamycin suppresses T-cell activation by impairing the T-cell response to lymphokines such as interleukin-2 (IL-2) and interleukin-4 (IL-4). In addition, rapamycin blocks the proliferative response of cell lines to a variety of hematopoietic growth factors, including interleukin-3 (IL-3), interleukin-6 (IL-6), granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage-colony stimulating factor (GM-CSF), and kit ligand (KL), suggesting that it should be a strong inhibitor of hematopoiesis. In this report, we studied the effects of rapamycin on different hematopoietic cell populations in vitro and in vivo. In vitro, rapamycin inhibited the proliferation of primary bone marrow cells induced by IL-3, GM-CSF, KL, or a complex mixture of factors present in cell-conditioned media. Rapamycin also inhibited the multiplication of colony-forming cells in suspension cultures containing IL-3 plus interleukin-1 (IL-1) or interleukin-11 (IL-11) plus KL. In vivo, treatment for 10 to 28 days with high doses of rapamycin (50 mg/kg/d, orally) had no effect on myelopoiesis in normal mice, as measured by bone marrow cellularity, proliferative capacity, and number of colony-forming progenitors. In contrast, the same treatment strongly suppressed the hematopoietic recovery normally seen 10 days after an injection of 5-fluorouracil (5-FU; 150 mg/kg, intravenously [i.v.]). Thus, rapamycin may be detrimental in myelocompromised individuals. In addition, the results suggest that the rapamycin-sensitive cytokine-driven pathways are essential for hematopoietic recovery after myelodepression, but not for steady-state hematopoiesis.

Animals↗
PubMed1994

A thyroid hormone receptor-dependent glucocorticoid induction.

Glucocorticoid and thyroid hormones exert their effects in many body tissues by binding to their respective receptors. The search for possible cross-talking mechanisms in overlapping target cells led to the discovery of synergism between a thyroid hormone receptor-binding site and a cryptic glucocorticoid-responsive element. Glucocorticoid responsiveness could only be detected in the presence of thyroid hormone and its receptor. This synergism requires the glucocorticoid receptor (GR) DNA-binding domain and is mediated by the transactivation domains. We found that synergism also occurs when the thyroid hormone receptor is replaced by the retinoic acid receptor or the GR is replaced by the progesterone receptor. Synergism is qualitatively independent of the type of thyroid hormone receptor-binding site and promoter. In several combinations of promoter and response elements, including a retinoic acid response element, T3 induction was only seen in the presence of the cryptic glucocorticoid-responsive element, GR, and glucocorticoids.

Animals↗
PubMed1994

Factors influencing nuclear receptors in transcriptional repression.

Members of the steroid receptor superfamily, like other transcription factors, can function as transcriptional inducers as well as repressors of transcription. The mechanisms by which repression is achieved seem to be specific for the factors and regulatory sequences involved. Silencing activity is conferred by the DNA bound v-ERBA, which is able to repress the activity of a complete or of a minimal promoter. Removal of the T3 or RA ligands converts the activated form of TR or RAR into a silencing conformation. Ligand-free TR, RAR or v-ERBA synergize with the DNA-bound negative protein 1 (NeP1) in a specific silencer sequence. In contrast to silencing, competitive repression is seen for specific negative hormone response elements. These elements are characterized by the presence of binding sites for other transcription factors.

Animals↗
PubMed1993

Fast chemiluminescent measurement of RNA polymerase activity based on photon counting technology.

A fast and simple assay for T7 RNA polymerase based upon chemiluminescent detection of the synthesized, digoxigenin-labeled RNA on a nylon membrane with anti-digoxigenin coupled alkaline phosphatase and CSPD as substrate is described. Activity of RNA polymerase is determined with high sensitivity by quantifying the emitted light of the microplate-formatted dot-blot membrane with a photon counting microplate luminometer and a specially designed filter adapter. The described method is one example for the application of this new adapter to measure luminescent membrane filters.

DNA-Directed RNA Polymerases↗
PubMed1993

Tennis elbow: a biomechanical and therapeutic approach.

Lateral epicondylitis, one of the most common lesions of the arm, affects some 50% of tennis players. This condition poses a problem in clinical management because treatment is dependent not only on proper medical therapy but also on correction of the improper on-court biomechanics. The most common flaw is a late contact on the backhand groundstroke, forcing the player to extend the wrist with the extensor muscles. This action predisposes to trauma of the tendon fibers at the lateral epicondyle. Understanding the biomechanics will better prepare the physician to advise the patient and to communicate with a tennis teaching professional to facilitate long-term relief.

Acupuncture Therapy↗
PubMed1992

Antihypertensive and metabolic effects of single and combined atenolol regimens.

The antihypertensive and metabolic effects of placebo (PL), a fixed combination of hydrochlorothiazide (25 mg) and triamterene (50 mg) (HCTZ/TRI), atenolol (25 mg) (Atc-25), atenolol (50 mg) (Ate-50) and their combination with HCTZ/TRI given once daily, were tested on 256 patients with mild-to-moderate essential-hypertension. After 3 weeks of PL monotherapy, 43 patients were randomized to PL (group 1), 41 patients to HCTZ/TRI (group 2), 44 patients to Ate-25 (group 3), 42 patients to Ate-50 (group 4), 43 patients to Ate-25/HCTZ/TRI (group 5), and 43 patients to Ate-50/HCTZ/TRI (group 6) in a double-blind parallel design study and were followed for 4 weeks. At the end of week 7, those patients who were randomized to groups 5 and 6 were allowed to continue for an additional 12 weeks, if their arterial pressure was satisfactorily controlled. Complete blood counts, blood chemistries, urinalyses, and electrocardiograms were done initially and during the study. Monotherapy with HCTZ/TRI, Ate-25, and Ate-50 had significant and equal antihypertensive effects compared with placebo. (P less than .01). However, the combination of Ate-25/HCTZ/TRI and Ate-50/HCTZ/TRI resulted in further reduction of arterial pressure with the effect being greatest with Ate-50/HCTZ/TRI (P less than .001). Patient groups 3 through 6 had also slower heart rates compared with groups 1 and 2 (P less than .01). Mild, but statistically significant, increases in BUN, glucose, triglycerides, and uric acid were noted in groups 2, 5, and 6 (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Atenolol↗
PubMed1991

Mapping the epitopes of neutralizing anti-human IL-3 monoclonal antibodies. Implications for structure-activity relationship.

The epitopes of neutralizing mAb were mapped in order to identify a receptor binding site on human IL-3 (huIL-3). To initiate this structure and activity analysis, four neutralizing mAb were selected on the basis of preventing rhuIL-3 stimulated proliferation of peripheral blood cells from a patient with chronic myelogenous leukemia (CML). In order to identify continuous epitopes, the neutralizing mAb were assayed in a solid-phase ELISA for their reactivity with either denatured rhuIL-3 or with the peptides generated by digestion of rhuIL-3 by using two different proteinases. Two of the neutralizing mAb recognized single fragments from both digestions. Amino acid (aa) sequence determination showed that these peptides overlap, defining a region of 22 aa (aa 29 to 50 of the mature rhuIL-3 protein). In a competition ELISA, the two continuous epitopes were shown to be linked to one another and to the two discontinuous epitopes, suggesting that all four neutralizing mAb bind to a discrete region of the IL-3 molecule, which might be involved in binding to the IL-3R.

Amino Acid Sequence↗
PubMed1990

Modular structure of a chicken lysozyme silencer: involvement of an unusual thyroid hormone receptor binding site.

Silencer elements, by analogy to enhancer elements, function independently of their position and orientation. We show that the chicken lysozyme silencer S-2.4 kb has many other characteristics in common with enhancer elements. The silencer is comprised of modules that independently repress gene activity--repression being increased synergistically when different or identical modules are combined. Repression is effective both on a complete and on a minimal promoter consisting of a TATA box only. One silencer module is bound in vitro by a 75-93 kd protein, termed NeP1; the other can be bound either by the product of the oncogene v-erbA or by the thyroid hormone receptor. This erbA binding site is unusual in that the palindromic sequence is inverted.

Animals↗
PubMed1990

Case study: disease prevention--new roles for nurses in rural Australia.

Nurses are taking a leading role in preventing disease on the North Coast of New South Wales. In addition to heart health programs, nurses are also involved in Early Childhood Clinics, immunization campaigns, pap smear and breast self-exam campaigns, nutrition education and walking-for-pleasure groups. It would be safe to say that without nurses making new roles for themselves, there would be very few disease prevention campaigns on the North Coast.

Community Health Nursing↗
PubMed1989

Cooperative interaction of chicken lysozyme enhancer sub-domains partially overlapping with a steroid receptor binding site.

Expression of the lysozyme gene is a marker for the differentiation of macrophages, lysozyme transcription being gradually increased during maturation. We have analyzed the fine structure and function of two macrophage-specific enhancer elements of the chicken lysozyme gene (E-2.7 kb and E-0.2 kb). Both increase their activities upon LPS induction, both contain multiple binding sites for similar or identical nuclear factors and both can be divided into two functional modules. For the E-0.2 kb enhancer we found a synergistic activity of the modules to be dependent on their distance. Binding sites for nuclear proteins within enhancer E-0.2 kb overlap substantially with the previously identified progesterone/glucocorticoid receptor binding site, which is required for steroid induction of lysozyme transcription in the oviduct.

Animals↗
PubMed1987

Lysozyme gene activity in chicken macrophages is controlled by positive and negative regulatory elements.

The chicken lysozyme gene is constitutively active in macrophages and under the control of steroid hormones in the oviduct. To investigate which DNA elements are involved in the control of its expression in macrophages we performed transient DNA transfer experiments with two different types of plasmids: 5'-deletion mutants of the upstream region of the chicken lysozyme gene and different fragments from this area in front of the thymidine kinase promoter (herpes simplex virus), each placed in front of the CAT (chloramphenicol acetyl transferase) coding sequence. Two enhancers (E-2.7 kb and E-0.2 kb) were characterized. They are active in macrophages, but not in chicken fibroblasts. Furthermore a negative element (N-2.4 kb) was identified, which is active in fibroblasts and promyelocytes, but not in mature macrophages. The combined action of all three elements contributes to the observed lysozyme gene activities: no activity in fibroblasts, moderate activity in promyelocytes and high activity in mature macrophages.

Animals↗
PubMed1987

Activity of two different silencer elements of the chicken lysozyme gene can be compensated by enhancer elements.

The chicken lysozyme gene is constitutively expressed in macrophages. Transfection of recombinant genes containing different portions of the lysozyme 5' upstream region revealed the existence of two negative transcriptional elements within 1 kb upstream of the start sites. Both elements placed upstream or downstream of a heterologous promoter-gene unit repress transcription independent of their orientation and are therefore called silencer elements, although their repressing activities 3' of the gene are reduced. One silencer (N-1.0 kb) at position -1 kb consists of the central region of the chicken middle repetitive sequence element CR1 and can be divided into two functional domains. N-1.0 kb is active in all cell types tested. The other silencer (N-0.25 kb) at position -0.25 kb shows reduced activity in primary macrophages. Despite their different specificities, the activity of both silencer elements can be influenced similarly. An inverse linear relationship between the transcriptional activity of the tested constructs and the potential inhibition by the silencer elements was found: weak transcription units can be strongly repressed, whereas strong transcription units can be only weakly repressed. Such a mechanism may help to turn off completely a particular gene in situations or tissues where strong positive regulators are inactive.

Animals↗
PubMed1987

Estimates of the population pharmacokinetic parameters and performance of Bayesian feedback: a sensitivity analysis.

We investigated the influence of bias in the estimates of the population pharmacokinetic parameters on the performance of Bayesian feedback in achieving a desired drug serum concentration. Three specific cases were considered (i) steady-state case, (ii) lidocaine example, and (iii) mexiletine example. Whereas in the first case both the feedback and the desired concentration represented steady-state values, in the lidocaine and mexiletine examples the feedback concentration was assumed to be sampled shortly after starting therapy. RMSE was used as a measure of predictive performance. For the simple steady-state case the relationship between RMSE and bias in the parameter estimates describing the prior distribution could be derived analytically. Monte Carlo simulations were used to explore the two non-steady-state situations. In general, the performance of Bayesian feedback to predict serum concentrations was relatively insensitive to bad population parameter estimates. However, large changes in RMSE could be observed with small changes in the true variance component parameters in particular in the intraindividual residual variance, sigma 2 epsilon, indicating that the prediction interval, in contrast to point prediction, is sensitive to bias in the estimates of the population parameters.

Bayes Theorem↗