Distributing working versions of published mathematical models for biological systems via the Internet.

Mathematical models are useful tools for investigating complex systems. By representing physiological systems as models, theories can be tested quantitatively against data from the system. Models can be used to explore new theories prior to experimentation and to design studies to optimize experimental resources. They can also be used as teaching tools to illustrate physiochemical principles. In spite of their usefulness and the time invested in developing models, published models are often underused due to the difficulty in obtaining working versions of the model. To address this problem we have designed a library for mathematical models of biological systems on the Internet. The library contains published models of biological systems in formats compatible with several modeling packages, from the fields of physiology, metabolism, endocrinology, biochemistry, and chemistry. The models can be viewed graphically, model solutions can be viewed as plots against data, and models can be downloaded to be run with software on the user's own system. The address of the library is: http://biomodel.georgetown.edu/model/ Investigators are invited to submit working versions of published models to the library. Models can be submitted electronically at the time a manuscript is accepted for publication. As journals go online, articles containing models can be linked to working versions of the models in the library. By increasing access to working versions of models, more of the investment in kinetic studies and model development can be realized.

Estimates of validity and reliability for the hemispheric mode indicator.

Concurrent validity of scores of the Hemispheric Mode Indicator (a measure of cognitive hemispheric dominance) was assessed by product-moment correlation with scores for the Human Information Processing Survey (a more-studied measure of hemispheric dominance) for 27 nurse-anesthetist students and 94 medical students (r = .61 and .69, respectively). For 70 of the medical students, test-retest stability was only fair (r = .74). For 525 undergraduates and 156 medical students, although alpha coefficients were .78 and .84, respectively, consideration of interitem correlations and principal components analyses indicated that some of the Hemispheric Mode Indicator's items are unsuitable as worded and that the 32 items probably represent more than one underlying latent variable.

Endothelins belong to the assortment of mast cell-derived and mast cell-bound cytokines.

Local accumulation of endothelins (ETs) as cytokine-like factors via autocrine/paracrine mechanisms seems to represent an important aspect of their pathophysiological action. This assumption prompted us to investigate mast cells as a possible source of these peptides. With the use of a combination of high-performance liquid chromatography and a radioimmunoassay specific for endothelin-1 (ET-1), 3-week-old cultures of primary murine bone marrow mast cells (BMMC) as well as various mast cell lines were shown to contain and secrete immunoreactive ET-1. The amounts of this peptide were constitutively high in cellular extracts of BMMC, while there was considerable variation in the basal cellular content among mast cell lines, ranging from high (C57) to undetectable (RBL) levels. Treatment of the cells with the combination of phorbol myristate acetate (PMA) and A23187 for 5 h led to induction of ET-1 production in all cases tested. In contrast to the rapid stimulation by PMA/A23187 of histamine release from BMMC or C57 cells, however, no ET-1 secretory response was noted as early as 30 min after this combined treatment. Moreover, stimulation of mast cells with crosslinked IgE for 30 min or 5 h did not affect ET-1 secretion, suggesting that mast cell ET-1 release is not directly related to mast cell degranulation. After exposure of the cells to crosslinked IgE for 20 h, however, there was a distinct increase in immunoreactive ET-1 in the medium, to approximate 10 times the basal level. Polymerase chain reaction (PCR) analysis of mRNA expression in mast cells revealed that the amount of ET-1 PCR product, which is low or undetectable under nonstimulated conditions, is enhanceable by both PMA/A23187 and crosslinked IgE. The IgE-mediated induction kinetics for ET-1 mRNA parallel the kinetics obtained with PMA/A23187, albeit at somewhat lower levels. With the use of fluorescent ligand binding/flow cytometry as a screening method and a radioreceptor assay as the confirming method, mast cells were found to express a single class of high affinity ET receptors with distinct selectivity for ET-1 and a pharmacological profile resembling that of the ETA type ET receptor. Stimulation of mast cell ET-1 receptors did not provoke histamine release, nor did it result in a mitogenic response of BMMC. In conclusion, mast cells synthesize and secrete ET-1 and have ET receptors, suggesting that ET-1 may participate in mediating mast cell-related long-term changes in the microenvironment, e.g., in smooth muscle tone or the proliferation rate of fibroblasts.

BioSYNTHESIS: access to a knowledge network of health sciences databases.

Users of the IAIMS Knowledge Network at the Georgetown University Medical Center have access to multiple in-house and external databases from a single point of entry through BioSYNTHESIS. The IAIMS project has developed a rich environment of biomedical information resources that represent a medical decision support system for campus physicians and students. The BioSYNTHESIS system is an information navigator that provides transparent access to a Knowledge Network of over a dozen databases. These multiple health sciences databases consist of bibliographic, informational, diagnostic, and research systems which reside on diverse computers such as DEC VAXs, SUN 490, AT&T 3B2s, Macintoshes, IBM PC/PS2s and the AT&T ISN and SYTEK network systems. Ethernet and TCP/IP protocols are used in the network architecture. BioSYNTHESIS also provides network links to the other campus libraries and to external institutions. As additional knowledge resources and technological advances have become available. BioSYNTHESIS has evolved from a two phase to a three phase program. Major components of the system including recent achievements and future plans are described.

Medical Facts File: a self service database of reference information.

The Dahlgren Memorial Library, Georgetown University Medical Center, will demonstrate Medical Facts File, a newly developed in-house database of general medical information. The file content emerged from the library's experience with commonly asked reference questions and the need to develop a database as an online source for users seeking quick answers to medical queries. Medical Facts File joins a growing family of over 18 databases which comprise Georgetown's IAIMS Knowledge Network. Use scenarios will demonstrate how an online search is initiated, either directly or as a prompt from one of the other online databases. The design of Medical Facts File at the Dahlgren Memorial Library began in late 1989 with a publishing section on instructions for authors planning to submit manuscripts to a variety of prominent medical journals. Since then, seven sections have been identified for the database. Three sections are highlighted for presentation, although work on the project is on-going. Medical Facts File is an easy-to-use, time saving system that facilitates tedious searching through a multitude of library sources. It provides users with a self-service, information look-up system.

Adenosine and related compounds counteract tumor necrosis factor-alpha inhibition of neutrophil migration: implication of a novel cyclic AMP-independent action on the cell surface.

Human rTNF-alpha (greater than or equal to U/ml) decreased PMN nondirected and directed migration to FMLP to approximately 50% of control. Adenosine (100 microM) almost completely restored hrTNF-inhibited migration (nondirected from 54 to 92% and directed migration to from 54 to 93% of control). The lowest concentration of adenosine that restored hrTNF-inhibited migration was 3 microM, and the adenosine analogue, 5'-(N-cyclopropyl)-carboxamido-adenosine (CPCA) was more potent than adenosine. Although CPCA binds to A2-receptors and stimulates adenylate cyclase, the reversal of hrTNF-inhibited chemotaxis was found to be independent of both PMN cAMP content and binding to A2-receptors, because neither 8-Br-cAMP nor pertussis adenylate cyclase restored hrTNF-inhibited PMN chemotaxis and the A2-receptor antagonist, 1,3-dipropyl-7-methylxanthine decreased CPCA stimulated cAMP but enhanced CPCA-restoration of hrTNF-inhibited chemotaxis. The effect of adenosine could be augmented by inhibition of adenosine uptake and decreased by adenosine deamination. Pentoxifylline, (3,7 dimethyl-1-[5 oxo-hexyl] xanthine), like adenosine also restored PMN chemotaxis inhibited by hrTNF. The adenosine receptor antagonist, 1,3-dipropyl-8(phenyl-p-acrylate)-xanthine (BW A1433U), decreased restoration of hrTNF-inhibited chemotaxis by CPCA or pentoxifylline. Thus, the inhibitory effect of hrTNF on PMN migration can be counteracted by adenosine, CPCA, pentoxifylline, and compounds that increase adenosine availability to the surface of the PMN. Inasmuch as an A1-selective agonist N6-cyclopentyladenosine was less active, and the action of the A2-selective agonist CPCA was enhanced by an A2-receptor antagonist, we hypothesize that neither A1 or A2 receptors are involved in adenosine restoration of hrTNF-inhibited chemotaxis. Further, increased cAMP, an A2-regulated event, does not cause the effect, and adenosine restoration of hrTNF-inhibited migration does not appear to be mediated by changes in PMN [F-actin], FMLP receptor expression, or cytosolic calcium. Hence, the restoration of hrTNF-inhibited chemotaxis is controlled by a novel cyclic AMP-independent action on the PMN surface.

Outpatient management of selected infants younger than two months of age evaluated for possible sepsis.

Previously healthy infants younger than 2 months of age without evidence of soft tissue or musculoskeletal infection who had white blood cell counts between 5000 and 15,000/mm3, band form counts less than or equal to 1500/mm3, urinalysis less than or equal to 10 white blood cells/high power field (spun sediment) and stool less than or equal to 5 white blood cells/high power field (if diarrhea) were considered at low risk for a serious bacterial infection. Infants meeting these criteria whose parents were judged to be adequate observers and had a telephone and automobile were eligible for outpatient management. Infants were given ceftriaxone to cover the possibility that the low risk criteria might miss more infants with serious bacterial infections than was predicted. From Jan. 1, 1987 to May 31, 1989, 86 infants younger than 2 months were enrolled. There were no serious complications in these infants. Twelve had transient problems possibly related to the intramuscular ceftriaxone therapy. One low risk infant was hospitalized for Neisseria meningitidis bacteremia and five other infants were hospitalized for medical or social reasons. All six hospitalized infants had short admissions and did well. This study supports the continued use of the low risk criteria to distinguish infants unlikely to have a serious bacterial infection. Furthermore, in a selected group of low risk infants, outpatient management may be an acceptable alternative to inpatient therapy.

Music programs for the institutionalized elderly in a midwestern metropolitan area.

This investigation concerned the status of music programs in licensed nursing homes in St. Louis, Missouri. Data were obtained by means of a mailed questionnaire, interviews with selected administrators, and visits to selected homes. Almost all of the institutions surveyed offered musical activities for their residents. In many instances, these consisted largely of recreational singing or visits to the institution by outside performing ensembles. In a few instances, more complete music programs were offered, in which residents benefited not only from the use of music for recreation but also from its educational and therapeutic potential.