Phenotypic characterization and ontogeny of mesodermal-derived and endocrine epithelial components of the human thymic microenvironment.

Using murine monoclonal antibodies TE-4 and TE-7 raised against human thymic stroma, we identified two distinct and mutually exclusive thymic microenvironment components: the thymic endocrine epithelium (TE-4+) and mesodermal-derived fibrous stroma (TE-7+). TE-4-reactive epithelium did not react with antibody TE-7, contained thymosin alpha 1 and keratin, and expressed other known markers of thymic endocrine epithelium (A2B5 and p19). Moreover, TE-4+ thymic epithelial cells strongly expressed class I (HLA-A, -B and -C) and class II (Ia-like) major histocompatibility complex (MHC) antigens. In contrast, TE-7+ thymic fibrous stroma did not react with antibody TE-4, did not contain thymosin alpha 1 nor keratin, and did not express the thymic endocrine epithelium markers A2B5 and p19. TE-7+ thymic stromal cells weakly expressed class I and did not express class II MHC antigens. Both TE-4+ and TE-7+ thymic microenvironment compartments were identifiable in thymus from 7 wk gestation through adult life. At 7 wk fetal gestation, TE-7+ stroma surrounded a cylindrical TE-4+, A2B5+ thymic epithelial rudiment. Between 10 and 15 wk fetal gestation, TE-7+ thymic stroma surrounded early thymic lobules. By 15 wk fetal gestation, antibody TE-4 defined subcapsular cortical and medullary zones of endocrine thymic epithelium, while antibody TE-7 bound to interlobular fibrous septae, vessels, and thymic fibrous capsule. While otherwise specific for endocrine thymic epithelium, antibody TE-4 reacted with the basal layer of squamous epithelium in skin, tonsil, conjunctiva, and upper esophagus.

Expression of antigens by cultured epithelial cells: comparison of epidermis and thymic epithelium.

We have established long term in vitro cultures of human thymic epithelium and human epidermis free of contaminating fibroblasts. The cultured cells were examined using a panel of monoclonal antibodies which were raised against human thymic stroma and recognize tissue specific differentiation antigens of human epidermis and thymic epithelium. A subset of cultured epidermal cells (50%) and thymic epithelial cells (18%) expressed the TE-4 antigen characteristic of basal keratinocytes in skin and endocrine epithelium found in the subcapsular cortex and medulla of the thymus. Subpopulations of the cultured cells expressed the antigens detected by antibodies TE-8 and TE-15. In tissue sections antibodies TE-8 and TE-15 bound to the stratum granulosum and stratum corneum of skin and to the Hassall's bodies of thymus, and therefore recognize antigens characteristic of late stages of keratinized epithelial differentiation. In addition, a subset of thymic epithelial cells expressed the antigen detected by antibody TE-3 which is expressed by nonendocrine thymic epithelium found in the thymic cortex. Thus, in vitro cultures of both epidermal and thymic epithelial cells expressed the entire array of differentiation antigens detected by our panel of monoclonal antibodies. This approach can be used to evaluate the role of components of the thymic microenvironment at various stages of differentiation on developing T lymphocytes. In addition, the cultured epidermal cells can be used to evaluate epidermis as a site of extrathymic T cell maturation.

Computerized decision support based on a clinical practice guideline improves compliance with care standards.

PURPOSE: Clinical guidelines are designed to assist in the management of specific diseases; however, these guidelines are often neglected in the delivery of care. The purpose of this study was to determine whether clinician use of an clinical practice guideline would increase in response to having, at the patient visit, a decision support system based on a practice guideline that generates a customized management protocol for the individual patient using data from the patient's electronic medical record. SUBJECTS AND METHODS: In a 6-month controlled trial at a primary care clinic, 58 primary care clinicians were randomized to receive either a special encounter form with the computer-generated guideline recommendations or a standard encounter form. The effect of computer-generated advice on clinician behavior was measured as rate of compliance with guideline recommendations. Data from 30 clinicians were analyzed; data from 28 clinicians were excluded because these clinicians did not meet predefined criteria for minimum exposure to diabetic patient care. RESULTS: Availability of patient management recommendations generated by the decision support system resulted in a two-fold increase in clinician compliance with care guidelines for diabetes mellitus (P = 0.01). Median compliance for the group receiving the recommendations was 32.0% versus 15.6% for the control group. CONCLUSION: Decision support based on a clinical practice guideline is an effective tool for assisting clinicians in the management of diabetic patients. This decision support system provides a model for how a clinical practice guideline can be integrated into the care process by computer to assist clinicians in managing a specific disease through helping them comply with care standards. Use of decision support systems based on clinical practice guidelines could ultimately improve the quality of medical care.

In vitro growth and phenotypic characterization of mesodermal-derived and epithelial components of normal and abnormal human thymus.

Long-term in vitro cultures of human thymic tissue were established and phenotypically characterized using monoclonal reagents that define distinct components of the human thymic microenvironment. The epithelial component of the thymus, defined by monoclonal antibodies TE-3, TE-4, BBTECS, and AE1 (anti-keratin) was isolated from the mesodermal component, defined by antibody TE-7, and maintained separately in long-term culture. The epithelial cells were subcultured repeatedly and recovered from storage in liquid nitrogen. The in vitro phenotype of the cultured cells was compared to that of cultured human epidermal cells. A subpopulation of cultured thymic epithelial cells along with a subpopulation of cultured epidermal cells expressed antigens (TE-8, TE-15) characteristic of late stages of keratinized epithelial cell differentiation. Thus, we have established a system whereby components of the human thymic microenvironment can be cultivated in vitro while maintaining the capacity to differentiate. This approach can be used to evaluate the role of components of the thymic microenvironment at various stages of differentiation on developing T lymphocytes. In addition, keratin-containing thymic epithelial cells were successfully cultured from thymuses obtained from patients with myasthenia gravis and thymoma. Cultivation of abnormal thymic epithelium will provide insight into aberrant T lymphocyte-thymic epithelial interaction.

Siegfried: System for Interactive Electronic Guidelines with Feedback and Resources for Instructional and Educational Development.

The proliferation of clinical practice guidelines (CPGs) has necessitated computerized solutions for guideline distribution and implementation. In this paper we describe a Web-based system that interactively presents CPGs at the point of care. Our system, known as Siegfried, provides a generalized solution for implementing CPGs by maintaining the guideline knowledge base separate from the application that presents the guidelines. As a result of this design, new CPGs can be easily added and existing CPGs can be expeditiously modified without additional programming. This system also solicits feedback from users regarding guideline recommendations and provides hypertext links to relevant Web-based instructional and educational resources.

Factors influencing uptake of pharmacogenetic testing in a diverse patient population.

BACKGROUND: The successful integration of pharmacogenetic (PGx) testing into clinical care will require attention to patient attitudes. In this study, we aimed to identify the major reasons why patients would or would not consider PGx testing and whether these factors differed by race, socioeconomic and insurance status, and medical history. METHODS: We developed and conducted a survey within the adult patient population of the Duke Family Medicine Center. RESULTS: Of 75 completed surveys (65% African-American), 77% indicated they were 'very likely' or 'somewhat likely' to take a PGx test. Respondents who had experienced a side effect were significantly more likely to indicate they would take a PGx test and expressed greater interest in learning more about testing than those who had not. Drug safety and effectiveness were the major reasons to have PGx testing. Privacy concerns and lack of insurance coverage for testing were the major reasons to decline testing. CONCLUSIONS: We found no differences in interest in PGx tests by race or socioeconomic status, but found stronger interest from those with a history of side effects and private insurance. While the overall support of PGx testing is encouraging, greater reassurance of medical privacy and development of educational resources are needed.

A model for adapting clinical guidelines for electronic implementation in primary care.

Medical informaticians who seek to implement clinical guidelines by computer must be aware of a significant gap that exists between guideline development and utilization. In order to be effective, guideline recommendations must be followed by clinicians; in order for clinicians to follow willingly, they must agree with the guidelines. This paper presents a model process for building consensus among clinicians that can be used to obtain support for guideline recommendations prior to their electronic implementation. This approach involves initial presentation of the guidelines by a specialist, iterative cycles of surveying clinicians' opinions about the guidelines and revising the guidelines, supervision of the process by a practice opinion leader, and final group discussion of the revised guidelines to reach consensus. This model was successfully used to adapt guidelines for the continuing care of patients with diabetes mellitus that were subsequently implemented electronically with broad support of the primary care clinicians using them. The model minimized the need for lengthy group discussion by surveying individuals' attitudes and working through a practice opinion leader to gain consensus support for the guidelines. An efficient approach for developing support for guidelines among practitioners will facilitate the electronic implementation of guidelines and lead to enhanced compliance with guidelines after implementation.

Electronically distributed, computer-generated, individualized feedback enhances the use of a computerized practice guideline.

Clinical guidelines have been developed to assist with the management of patient care; however, these guidelines are frequently neglected in clinical practice. Computer-generated reminders enhance guideline use, but these systems often fail to achieve high rates of guideline utilization. This study was designed to test the hypothesis that computer-generated, individualized feedback regarding adherence to care guidelines will significantly improve clinician compliance with guideline recommendations presented through a computer-assisted management protocol. Half of the 45 primary care clinicians employed at a primary care clinic affiliated with an academic medical center, were randomized to receive a biweekly electronic mail message consisting of a computer-generated report summarizing his/her response to care guideline recommendations for the diabetic patients seen during the previous 2 weeks. Clinician compliance with guideline recommendations was the primary outcome measure. This study demonstrated that the intervention significantly increased clinician compliance with the guideline recommendations without incurring high maintenance expenses. Median compliance among the intervention group was 35% versus 6.1% among the control group (p < 0.01). Electronically distributed, computer-generated, individualized feedback regarding clinician use of care guideline recommendations is an effective way to enhance compliance with a care guideline.

Development and evaluation of a Computer-Assisted Management Protocol (CAMP): improved compliance with care guidelines for diabetes mellitus.

Disease-specific standards for directing patient management are becoming increasingly important. These standards, however, are often not followed because they are not sufficiently integrated into the clinical care setting. In this study we describe the development and evaluation of a Computer-Assisted Management Protocol (CAMP) of care guidelines for diabetes mellitus. While other studies have shown improved compliance with rule-based reminders, the CAMP customizes disease-specific care guidelines to individual patients over time. We evaluated the effect of the CAMP on compliance with guidelines in a prospective, randomized controlled study. The study was performed at a family practice clinic where much of the patient record is maintained electronically on The Medical Record (TMR). The management protocol was developed from standards published by the American Diabetes Association. Fifty-eight providers were randomized to either receive or not receive the CAMP for diabetes. Compliance with standards was assessed by chart audits of all encounters with diabetic patients during the study interval. The following conclusion was made: the Computer-Assisted Management Protocol resulted in a statistically significant improvement in compliance with diabetes care standards.

Integration of clinical decision support with on-line encounter documentation for well child care at the point of care.

Electronic medical record systems and clinical practice guideline (CPG) support applications are emerging in the clinical environment to document and support care. Applications which integrate online documentation with CPG are often complex systems bound to a proprietary infrastructure and as such, can be difficult to adapt to changing care guidelines. This paper describes integration of point-of-care clinical documentation to an Internet-based CPG system that was easily modified, utilized available software resources, and separated patient information from CPG. The system combined a text-based encounter documentation tool, Inbox, with a web-based CPG system, SIEGFRIED (System for Interactive Electronic Guidelines with Feedback and Resources for Instructional and Educational Development), which interactively presented care guidelines to providers. Age-specific well child care documentation templates were developed using Inbox for point-of-care documentation. SIEGFRIED contained the knowledge base of child safety education guidelines and executed independent of the program presenting the guidelines. The CPG were accessed from within the documentation template via an Internet hyperlink. Patient chart evaluation indicated that 77% of safety topics were reviewed and 32% of the charts contained documentation indicating all the safety topics were reviewed. Last, routine use of the Inbox-SIEGFRIED system was not realized due to the clinical time constraints and workload of the medical providers, and lack of data entry experience. A user survey indicated time cost (network access and software execution) were negative aspects of the system. However, the system function was highly regarded and the Internet-based patient education materials were described as useful and accurate. In summary, the system was functional, met original development goals, and provided valuable patient education materials; however, routine system use was prevented by time requirements. We recommend further development be oriented towards integrating the identified beneficial components of the system into clinician workflow.

A systematic process for converting text-based guidelines into a linear algorithm for electronic implementation.

Clinical practice guidelines are increasingly important for improving the quality and the process of healthcare delivery. Unfortunately, most guidelines are available only in a text-based format, which is difficult to integrate into clinical practice. Computers can facilitate guideline integration into clinical practice; however, this migration to computers requires translating text into intermediary representations. One type of representation that is readily adaptable for computerization is a linear algorithm. This paper describes a systematic process to convert text-based clinical practice guidelines into a linear algorithm with structured content, as an intermediate step to electronic implementation. The process includes: 1) defining applicability criteria, 2) identifying entry points, 3) defining decision points, 4) defining actions, 5) creating a linear algorithm that links decision points and actions, and 6) adding supporting resources. This process has been used successfully to prepare more than two dozen guidelines for computerization. It has been tested by several physicians and informaticians and shown to be transferable to various user groups. The availability of a systematic process to convert text-based guidelines into a structured intermediary format for electronic implementation can facilitate the computerization of guidelines and can inform guideline content developers regarding the critical elements that need to be explicitly stated in guidelines to support electronic implementation.

Identification of design features to enhance utilization and acceptance of systems for Internet-based decision support at the point of care.

Extensive utilization of point-of-care decision support systems will be largely dependent on the development of user interaction capabilities that make them effective clinical tools in patient care settings. This research identified critical design features of point-of-care decision support systems that are preferred by physicians, through a multi-method formative evaluation of an evolving prototype of an Internet-based clinical decision support system. Clinicians used four versions of the system--each highlighting a different functionality. Surveys and qualitative evaluation methodologies assessed clinicians' perceptions regarding system usability and usefulness. Our analyses identified features that improve perceived usability, such as telegraphic representations of guideline-related information, facile navigation, and a forgiving, flexible interface. Users also preferred features that enhance usefulness and motivate use, such as an encounter documentation tool and the availability of physician instruction and patient education materials. In addition to identifying design features that are relevant to efforts to develop clinical systems for point-of-care decision support, this study demonstrates the value of combining quantitative and qualitative methods of formative evaluation with an iterative system development strategy to implement new information technology in complex clinical settings.

Documenting data delivery: design, deployment, and decision.

Developing and deploying informatics solutions which are useful and acceptable to busy physicians are challenging tasks. We describe the design, deployment, and evaluation process by which the delivery of routine clinical laboratory reports is automated using electronic mail. Data from TMR, an operational computer-based patient record (CPR), are presented to providers using an individualized, modern interface. This system is compared to the existing, paper-based system for delivery of data from the same CPR. Differences between the two systems of data delivery are analyzed, with emphases on 1) electronic documentation of data delivery and receipt, 2) electronic and/or paper documentation of clinical action taken as a result of laboratory reports, 3) timeliness of report availability, 4) costs, 5) workflow compatibility, and 6) physician satisfaction. The new delivery system employs inexpensive, commercially available software applications and entails only trivial changes to the proprietary CPR. Built into the new system are features which allow quantitative measurements of its performance for analysis along with survey-based user satisfaction data. The open systems design is deliberately non-proprietary, inexpensive, and generalizable. Accordingly, it offers practical possibilities for settings in which clinical information systems are just being planned, as well as for those in which such systems are already established.

The human thymic microenvironment. Phenotypic characterization of Hassall's bodies with the use of monoclonal antibodies.

The human thymic microenvironment is important in promotion of T cell maturation, particularly during early stages of thymic ontogeny. Hassall's bodies (HB) are epithelial swirls in the human thymic medulla that are thought to be derived from endocrine medullary thymic epithelium. To study the ontogeny and function of various components of the human thymic microenvironment, we have produced four monoclonal antibodies (TE-8, TE-15, TE-16, and TE-19) that selectively reacted in thymus with HB. Antibodies TE-8 and TE-16 reacted with the cells forming the outer rim of the HB swirl. Antibody TE-19 reacted with the entire cellular portion of HB and with epithelial cells immediately surrounding HB. Granular foci in the cellular swirls of greater than 90% of HB reacted with antibody TE-15. During thymic ontogeny, the antigens defined by antibodies TE-8, TE-15, TE-16, and TE-19 were first detected in fetal thymus on HB beginning at 16 wk gestation, the age when HB morphologically appear in the thymus. Aberrant expression of the antigens corresponding to antibodies TE-8, TE-15, TE-16, and TE-19 was observed on thymic tissue from individuals with severe cellular immunodeficiency disease. In human skin, antibodies TE-8, TE-16, and TE-19 reacted with the stratum granulosum; antibody TE-15 reacted with the stratum corneum. Thus, with the use of antibodies TE-8, TE-15, TE-16, and TE-19, we have identified HB as antigenically distinct regions of endocrine thymic epithelium. Furthermore, we have shown that these anti-HB reagents also selectively react with epidermal keratinocytes in the terminal stages of keratinocyte maturation.

Structuring clinical practice guidelines in a relational database model for decision support on the Internet.

The rapid proliferation of clinical practice guidelines (CPGs) has made computerization increasingly useful to clinicians. Computerization, however, requires transformation of the content and logic of each guideline into a computer-accessible form. In this project, we sought to use a relational database to construct a generalized guideline knowledge base for use with Internet-based decision support applications. We hypothesized that knowledge representation schemes could be developed to capture guideline content and logic within the constraints of a relational database model. In this paper we describe a database schema based on a relational model for computerizing CPGs using a hybrid of structured and procedural knowledge representation schemes. We developed and refined this model in the context of five diverse CPGs and found it accommodated all necessary representational requirements.

Development and use of a Guideline Entry Wizard to convert text clinical practice guidelines to a relational format.

Computerization of clinical practice guidelines (CPGs) has been proposed as one solution to enhance the use of guidelines in influencing standard clinical care. However, the conversion of text guidelines to the format required by a computer program is a major barrier. Clinicians who best understand the content of CPGs are typically ill equipped to convert textual guidelines into a computer accessible format. The potential of knowledge acquisition tools to assist in this process has been documented in the literature. In this paper we describe an application prototype, the Guideline Entry Wizard, created to assist in the conversion of text CPGs to a structured format within a relational database. We have tested this application through the input of information from several CPG. The application is a prototype for a more advanced tool. We have used this prototype to enter several CPGs and have demonstrated its effectiveness in inputting guideline content into a knowledge base.

The thymic microenvironment. Characterization of in vitro differentiation of the IT26R21 rat thymic epithelial cell line.

We have previously postulated an in vivo pathway of thymic epithelial (TE) cell maturation in pre- and postnatal thymus, whereby endocrine medullary TE cells terminally differentiate to form Hassall's bodies. Epithelial-cell differentiation has been well documented in vitro using epidermal keratinocytes. Therefore, to characterize TE-cell differentiation in vitro, we observed clones of the rat TE cell line, IT26R21, after 4 and 14 days in culture. We found alterations in cell morphology, the cessation of cell proliferation, and the acquisition of a differentiation antigen defined by monoclonal antibody TE-19 (a marker of terminally differentiated epithelial cells). At light and electron microscopy, we detected progressive TE-cell stratification and squamous-cell formation between 4 and 14 days of culture. Autoradiography on day 14 showed that squamous TE cells in stratified layers did not incorporate tritiated thymidine, while surrounding smaller cells adhering to the substratum continued to synthesize DNA. At indirect immunofluorescence, only 3% of cells reacted with monoclonal antibody TE-19 at day 4, while on day 14, 22% of the TE cells were TE-19 positive (P less than 0.02). Antibody-TE-19 reactivity was limited to stratified, squamous TE cells. Additionally, we isolated a clone of the IT26R21 cell line that did not undergo these changes characteristic of TE cell differentiation. We conclude that IT26R21 TE cells are capable of undergoing programs of both terminal differentiation and cell renewal in vitro.

Integration of a computer-based patient record system into the primary care setting.

The use of computer-based patient record systems (CPRS) in the primary care setting will increase significantly over the next few years. Real-time, point-of-care use of such systems must provide adequate payback to justify the intrusion into the provider/patient relationship. The authors describe, through the transition of a legacy system into a state-of-the art system, how such a system might be integrated into the primary care setting. Information flow is organized around an event, such as a patient encounter, or around the patient. The Medical Record (TMR) optimizes the provider/computer interaction through the use of protocols and clinical guidelines. Documentation is enhanced through the use of computer-generated progress notes.

A Web link management tool for optimizing utilization of distributed knowledge in health care applications.

The number of health-related Web sites on the Internet is increasing. Incorporating these sites into clinical decision support systems and other health care applications can significantly enhance the educational and instructional value of such systems. While search engines exist for finding sites and criteria are available for assessing site quality, few tools are available for managing Web-based health care information. Management of Web-based information is particularly challenging because the information is continually changing and new resources are continually being added. In this paper, we describe the development and use of a Web-link manager for health care applications. This system retains search strategies for repeated use, catalogues search results in a search results database, accommodates tracking of site review and use status, and provides periodic checking of link integrity for sites that are used in local applications. The Web-link manager is currently in use to manage the links used in a clinical decision support system that presents clinical practice guidelines interactively to clinicians at the point of care.

Human T cell antigen expression during the early stages of fetal thymic maturation.

Human thymus tissue was examined from 7 wk of gestation through birth for the expression of antigens reacting with a panel of anti-T cell monoclonal antibodies. Additionally, the reactivities of reagents against the transferrin receptor, against leukocytes, against low m. w. keratins, and against major histocompatibility complex antigens were studied on human fetal thymic tissue. Frozen tissue sections were evaluated by using indirect immunofluorescence assays. At 7 wk of gestation, no lymphoid cells were identified within the epithelial thymic rudiment; however, lymphoid cells reacting with both antibody 3A1, a pan T cell marker, and antibody T200, a pan leukocyte reagent, were identified in perithymic mesenchyme. After lymphoid colonization of the thymic rudiment at 10 wk of fetal gestation, fetal thymic tissue reacted with antibodies T1, T4, and T8. At 12 wk of gestation, antibodies T3, T6, A1G3 (anti-p80, a marker of mature thymocytes), and 35.1 (anti-E rosette receptor) all reacted with thymic tissue. Our findings indicate that T cell antigens were acquired sequentially on thymocytes at discrete stages during the first trimester of human fetal development. The 3A1 antigen was present on fetal lymphocytes before lymphoid cell colonization of thymic epithelium, suggesting that passage through the thymus was not required for the expression of the 3A1 antigen by T cell precursors. The appearance of mature T cell antigens, T3 and p80, on thymocytes by 12 wk of gestation implies that the T cell antigen repertoire may be established in the thymus during the first trimester. Thus, a critical period of T cell maturation appears to occur between 7 and 12 wk of human fetal gestation.