Translocation of ricin across polarized human bronchial epithelial cells.

Due to widespread availability, toxicity, and potential for use as a bioterrorism agent, ricin is classified as a category B select agent. While ricin can be internalized by a number of routes, inhalation is particularly problematic. The resulting damage leads to irreversible pulmonary edema and death. Our study describes a model system developed to investigate the effects of ricin on respiratory epithelium. Human bronchial epithelial (HBE) cells were cultured on collagen IV-coated inserts until polarized epithelial cell monolayers developed. Ricin was added to the apical or basal medium and damage to the cell monolayer was then assessed. Within a few hours after exposure, the cell monolayer was permeable to paracellular passage of the toxin. A mouse anti-ricin antibody neutralized ricin and prevented cellular damage as long as the antibody was present before the addition of toxin. These studies suggested that effective therapeutic agents or antibodies neutralizing ricin biological activity must be present at the apical surface of epithelial cells. The in vitro system developed here provides a method by which to screen potential therapeutics for protecting lung epithelial cells against ricin intoxication.

The silencing mediator of retinoic acid and thyroid hormone receptors can interact with the aryl hydrocarbon (Ah) receptor but fails to repress Ah receptor-dependent gene expression.

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related chemicals causes a variety of tissue- and species-specific biological and toxicological effects, most of which are mediated by the aryl hydrocarbon receptor (AhR). The AhR complex is a ligand-dependent transcription factor that binds to its specific DNA recognition site as a dimer with the AhR nuclear translocator (ARNT) and activates gene transcription. Here, we have examined the ability of a nuclear corepressor, the silencing mediator of retinoic acid and thyroid hormone receptors (SMRT), to interact with and modulate AhR-dependent gene expression. Using glutathione S-transferase (GST) "pull-down" binding assays, we have mapped a major interaction between these factors to the silencing domain of SMRT and the PAS B ligand binding domain of AhR, and this interaction is unaffected by the addition of an AhR ligand. Association of SMRT with the AhR:ARNT:DNA complex was not detected by GST pull-down or gel retardation assays. Transient cotransfections of mammalian cells (Hepa1c1c7, MCF-7, and BG-1) with SMRT and a TCDD-inducible luciferase reporter containing the dioxin-responsive domain from the mouse CYP1A1 regulatory region revealed that SMRT does not repress, but enhances, AhR signaling. However, when a reporter containing a human CYP1A1 upstream region was cotransfected with SMRT into human MCF-7 cells, AhR-driven reporter activity was decreased by half, suggesting that SMRT acts on the human CYP1A1 promoter via a factor other than the AhR in MCF-7 cells. Furthermore, the interaction between SMRT and the AhR may have implications in pathways other than the AhR signaling pathway.

Analysis of the aryl hydrocarbon receptor (AhR) signal transduction pathway.

Analysis of the Ah Receptor Signal Transduction Pathway (Michael S. Denison, Jane M. Rohers, S. Renee Rushing. Carol L. Jones, Selwyna C. Tetangico, and Sharon Heath-Pagliuso, University of California, Davis, California).The protocols in this unit will allow researchers to detect the Ah receptor and characterize its functional activities (i.e., ligand binding, transformation and DNA binding, and gene expression) in their biological test system and to use these methods to detect chemical and biochemical events that affect this signaling system.

Completely submerged primary molars.

Two mixed dentition cases have been presented which became quite complicated because of ankylosed and submerged primary second molars. These cases demonstrate the need for an early orthodontic evaluation and interceptive orthodontics. The orthodontic and surgical procedures required for these two patients could have easily been avoided by removing the ankylosed primary molars and placing space maintainers. (Of course this depends upon the parents responding to their dental recall notices.) If a submerging primary molar is retained too long, the second premolar may become displaced superiorly and the permanent first molar may migrate mesially as it erupts. Both of these problems can be prevented by extracting the ankylosed primary second molar before it submerges below the mesial height of contour of the permanent first molar. A fixed space maintainer then becomes necessary to prevent loss of arch length by mesial migration of the permanent molar.

Antibodies to CD40 prevent Epstein-Barr virus-mediated human B-cell lymphomagenesis in severe combined immune deficient mice given human peripheral blood lymphocytes.

CD40 is expressed on both normal and neoplastic B lymphocytes. Signal transduction through CD40 in vitro has been shown to exert stimulatory effects on normal B cells and inhibitory effects on Epstein-Barr virus (EBV)-induced B-cell lymphoma lines and some other cell lines derived from patients with aggressive histology lymphoma. The transfer of normal human peripheral blood lymphocytes (huPBL) from EBV-seropositive donors into severe combined immune deficient (SCID) mice has been previously shown to result in the generation of human B-cell lymphomas. These tumors are similar to the highly aggressive EBV-induced lymphomas that can arise clinically after transplantation or in the setting of immunodeficiency. Treatment of huPBL-SCID chimeric mice with anti-CD40 or anti-CD20 monoclonal antibodies (MoAb) significantly delayed the development of EBV-induced B-cell lymphoma. However, the effects of the two MoAb were mechanistically distinct. Anti-CD40 treatment prevented lymphoma generation, while still allowing for functional human B-cell engraftment in the huPBL-SCID mice compared with mice receiving no treatment, all of which succumbed to lymphoma. By contrast, treatment with anti-CD20 significantly inhibited total human B-cell engraftment in the SCID recipients, which accounted for the absence of lymphomas. In vitro assays examining the transformation of human B cells by EBV also indicated that anti-CD40 could directly inhibit EBV-transformation, whereas anti-CD20 antibodies had no effect. Thus, anti-CD40 exerts selective effects to allow for the engraftment of normal human B cells and prevent the emergence of EBV lymphomas. Stimulation of CD40 by antibodies or its physiologic ligand may, therefore, be of significant clinical use in the prevention of EBV-induced B lymphomas that may arise when EBV-seropositive individuals receive immunosuppressive regimens after transplantation or in immune deficiency states, such as acquired immune deficiency syndrome.

How dentists perceive the effects of orthodontic extraction on facial appearance.

In recent years, orthodontic treatment, particularly that involving premolar extractions, has been alleged to cause flat facial profiles. Those who make such assertions also claim to be able to instantly identify from a distance faces of patients who have received orthodontic treatment. These are strong claims that could profoundly affect the public's perception of dentistry and its specialties. This study examined whether dentists could distinguish between profiles of treated and untreated patients as well as between patients who had undergone extraction and those who had not.

Nursing research priorities for the care of the naval hospital patient: a Delphi survey.

The purpose of this study was to identify priorities for nursing research in a naval hospital using the Delphi technique. A general objective was to provide empirically based information to guide the development of a nursing research program at a regional medical treatment facility. Via a three-round Delphi survey, priority research questions were identified for the nursing department of a naval regional medical treatment facility. A serendipitous result was the identification of nursing research priorities within a deployed naval fleet hospital.

Working smarter with patient-focused care.

Aspects of the patient-focused care approach make it clear that ideas that revolutionized other industries are just as useful to healthcare organizations. Lee Memorial Hospital in Fort Myers, Fla. and Atlanta's Northside Hospital have adopted this approach.

The role of the rural hospital emergency department.

Although rural hospital emergency departments are key components of rural health care, there is little medical literature describing their activities. This study examined the patient load of rural emergency departments in Mississippi. Each patient encounter was coded according to public health district, hospital number, patient number, age, sex, race, season, day of week, time, diagnosis, disposition, and method of payment (if available). The rural emergency departments were much busier when physician offices were closed, with the vast majority of patients being treated and sent home. Users of rural emergency departments had similar diagnoses and dispositions to users of urban emergency departments. Admitted patients tended to be older; almost one half of the patients transferred to other institutions had injuries. The findings have implications for the training of rural physicians and for policies relating to rural health care delivery.

Hospital of the Future--not just technology "talk".

Technology is gaining increasing attention and competitive importance in the healthcare industry, but healthcare administrators need more than just talk to make effective technology investments. Andersen Consulting and the American College of Healthcare Executives have created Hospital of the FutureSM, in Dallas, Texas, as a dynamic, evolving research and demonstration forum that allows healthcare administrators and providers to see potential technology solutions in action--in healthcare settings specifically designed to look and feel like the real thing. This article discusses the functionality and technical structure of Hospital of the Future, as well as the integration issues among disparate healthcare systems addressed in developing the display.

Effects of in vitro incubation on a zona binding site found on murine spermatozoa.

Murine cauda epididymal sperm possess a site, the acceptor, on the plasma membrane over the apical cap region of the acrosome which recognizes both a proteinase inhibitor of seminal vesicle origin and homologous zonae. The acceptor site may participate in both capacitation and zona binding. This presentation explores the effect of in vitro incubation in a medium known to induce capacitation on the binding capabilities of this site. Approximately 80% of fresh cauda epididymal sperm will bind the seminal inhibitor in vitro. Incubating sperm, pretreated with inhibitor for 2 hr in a medium (M199-M) known to support capacitation, reduces by 60% the number of sperm showing evidence of the inhibitor. No such decrease is seen when sperm are incubated in a medium (M199) that does not support capacitation. During the 2-hr incubation in either medium, 60-70% of the sperm retain two diverse components on the plasma membrane over the acrosome: a receptor for the Fc portion of IgG and an epitope recognized by a monoclonal antibody to the acceptor site. These observations suggest that the plasma membrane in the acrosome region of the cell remains structurally intact during incubation. Furthermore, sperm retain the ability to bind the seminal inhibitor during incubation. After a 2-hr incubation in M199-M, sperm pretreated with heat-solubilized zonae no longer bind the inhibitor. These sperm, however, retain the plasma membrane over the acrosomal cap region. When the sperm are incubated in M199, no decrease in inhibitor binding due to zona treatment is noted.(ABSTRACT TRUNCATED AT 250 WORDS)