Storylines of family medicine III: core principles-primary care, systems and family

Storylines of Family Medicine is a 12-part series of thematically linked mini-essays with accompanying illustrations that explore the many dimensions of family medicine, as interpreted by individual family physicians and medical educators in the USA and elsewhere around the world. In 'III: core principles-primary care, systems, and family', authors address the following themes: 'Continuity of care-building therapeutic relationships over time', 'Comprehensiveness-combining breadth and depth of scope', 'Coordination of care-managing multiple realities', 'Access to care-intersectional, systemic, and personal', 'Systems theory-a core value in patient-centered care', 'Family-oriented practice-supporting patients' health and well-being', 'Family physician as family member' and 'Family in the exam room'. May readers develop new understandings from these essays.

Single agent subcutaneous blinatumomab for advanced acute lymphoblastic leukemia

Blinatumomab is a BiTE® (bispecific T-cell engager) molecule that redirects CD3+ T-cells to engage and lyse CD19+ target cells. Here we demonstrate that subcutaneous (SC) blinatumomab can provide high efficacy and greater convenience of administration. In the expansion phase of a multi-institutional phase 1b trial (ClinicalTrials.gov, NCT04521231), heavily pretreated adults with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) received SC blinatumomab at two doses: (1) 250 μg once daily (QD) for week 1 and 500 μg three times weekly (TIW) thereafter (250 μg/500 μg) or (2) 500 μg QD for week 1 and 1000 μg TIW thereafter (500 μg/1000 μg). The primary endpoint was complete remission/complete remission with partial hematologic recovery (CR/CRh) within two cycles. At the data cutoff of September 15, 2023, 29 patients were treated: 14 at the 250 μg/500 μg dose and 13 at 500 μg/1000 μg dose. Data from two ineligible patients were excluded. At the end of two cycles, 12 of 14 patients (85.7%) from the 250 μg/500 μg dose achieved CR/CRh of which nine patients (75.0%) were negative for measurable residual disease (MRD; <10-4 leukemic blasts). At the 500 μg/1000 μg dose, 12 of 13 patients (92.3%) achieved CR/CRh; all 12 patients (100.0%) were MRD-negative. No treatment-related grade 4 cytokine release syndrome (CRS) or neurologic events (NEs) were reported. SC injections were well tolerated and all treatment-related grade 3 CRS and NEs responded to standard-of-care management, interruption, or discontinuation. Treatment with SC blinatumomab resulted in high efficacy, with high MRD-negativity rates and acceptable safety profile in heavily pretreated adults with R/R B-ALL.

A phase 1b study of blinatumomab with the anti-programmed cell death (PD)-1 antibody AMG 404 in adults with relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (ALL)

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Background: Preclinical data indicate that anti-PD-1 agents can facilitate activity of bispecific T-cell engager (BiTE) molecules. Here we assess the combination of the anti-CD19 BiTE molecule blinatumomab with the anti-PD-1 antibody AMG 404 in adults with R/R ALL (NCT04524455). Methods: Eligible adults with R/R ALL (Ph+ disease included) received 2-5 treatment cycles. Each cycle was 42 days, consisting of 4 weeks of cIV blinatumomab and a 2-week treatment-free interval as per label. In Cohort 1, AMG 404 was dosed IV at 240 mg every 4 weeks (Q4W); first dose was Day (D) 11 of Cycle (C) 1. Primary endpoints were dose-limiting toxicities (DLTs) and other adverse events (AEs). Results: As of 20 Dec 2021, patients (pts) from Cohort 1 (n=8) had median age of 57 (range: 24-73) y, 6/8 male, 6/8 Caucasian, 1 with extramedullary disease (duodenum), 2 with prior blinatumomab, and a median of 5 (2-15) prior treatment lines. Two pts remain on study and 2 completed the study; 4 pts discontinued the study due to death (n=3) or consent withdrawn (n=1). No DLTs were reported for the 3 evaluable pts. Of the 5 pts not evaluable for DLTs, in C1, 4 had disease progression and 1 an unrelated fatal pneumonia. Treatment-related grade (Gr) ≥3 and/or serious AEs in all 8 pts included cytokine release syndrome (CRS) (1 pt Gr 2, 1 pt Gr 1 and 3), Gr 3 increases in ALT and AST, Gr 3 fever, Gr 3-4 neutropenia, Gr 4 neutropenia/Gr 3-4 thrombocytopenia (same pt), Gr 2 sensorimotor polyneuropathy, Gr 3 hypertension, Gr 3 encephalopathy, and in 1 pt Gr 3-4 decreases in white blood cells, lymphocytes, and neutrophils. One pt developed Gr 3 SARS-COV-2 pneumonia on C2D25, resolving without clinical sequelae. C3 start was delayed by 12 days but protocol treatment resumed uneventfully. All 3 DLT-evaluable pts had a complete response (CR) or CR with partial hematologic recovery (CRh), 2/3 without measurable residual disease (MRD), within 2 cycles; the 3rd pt had an MRD response at the end of C3. Preliminary pharmacokinetic results for the combination of blinatumomab and AMG 404 demonstrated that their exposures were consistent with those observed for each as monotherapy and did not indicate any drug-drug interactions. To date, all samples tested for anti-blinatumomab antibodies have been negative. Conclusions: In this ongoing phase 1b study, the combination of blinatumomab with AMG 404 was tolerated with a manageable safety profile. No DLTs were reported. Enrollment continues in Cohort 2 in which AMG 404 is dosed Q4W at 480 mg starting on C1D1, 48 hours prior to blinatumomab. Clinical trial information: NCT04524455. [Table: see text]

The learning community faculty experience: how longitudinal relationships with learners enhance work meaning

INTRODUCTION

Work meaning has gained attention as an important contributor to physician job engagement and well-being but little is known about how faculty participation in medical school learning communities might influence this phenomena. Our study goals were to determine how physician faculty members may derive meaning from serving as mentors for longitudinal learning communities of medical students, to understand how that meaning may impact other areas of their work, and relate our findings to existing literature and theoretical frameworks.

METHODS

The research team conducted, recorded, transcribed, and coded 25 semi-structured telephone interviews of faculty mentors from four US medical schools with curricular learning communities. The team used an iterative interview coding process to generate final themes and relate these themes to existing literature.

RESULTS

The authors identified five themes of meaning faculty derive from participation as learning community mentors: "I am a better professional," "I am more connected," "I am rejuvenated," "I am contributing," and "I am honored." A sixth theme, "I am harmed," encompassed the negative aspects of the learning community faculty experience. The authors found that their identified themes related closely to the theoretical framework for pathways to meaningful work proposed by Rosso et al.

DISCUSSION

The alignment of the themes we identified on the experience of learning community faculty to existing literature on work meaning corroborates the theoretical framework and deepens understanding of beneficial and harmful learning community effects on faculty. As learning communities become increasingly common within medical schools, this understanding may be important for leaders in academic medicine considering potential indirect benefits of this educational model.

Opposition to Obamacare: A Closer Look

Prior telephone surveys have reported two main reasons for opposition to the Affordable Care Act (ACA): distrust of government and opposition to the universal coverage mandate. The authors set out to elucidate the reasons for this opposition. This article describes how the authors used qualitative methods with semistructured interviewing as a principal investigative method to gather information from people they met while bicycling across the United States from April through July 2016. During this time, the authors conducted open-ended, semistructured conversations with people they met as they rode their bicycles from Washington, DC, to Seattle, Washington. Informants were chosen as a convenience sample. One hundred sixteen individuals participated as informants. The majority of comments were negative toward the ACA. Conversations were categorized into four themes, which included the following: (1) The ACA has increased the cost of health insurance; (2) government should not tell people what to do; (3) responsibility for ACA problems is diffuse; and (4) the ACA should not pay for other people's problems. These face-to-face conversations indicated that opposition to the ACA may be due to the fact that many Americans have experienced an increase in the cost of insurance either through increased premiums or greatly increased deductibles. They blame this increase in cost on the ACA, President Obama, the government or insurance companies, and the inclusion of "others" in insurance plans. The authors discuss how these findings can influence medical education curricula to better prepare future physicians to discuss health policy issues with patients.

A Next-Generation TRK Kinase Inhibitor Overcomes Acquired Resistance to Prior TRK Kinase Inhibition in Patients with TRK Fusion-Positive Solid Tumors

Larotrectinib, a selective TRK tyrosine kinase inhibitor (TKI), has demonstrated histology-agnostic efficacy in patients with TRK fusion-positive cancers. Although responses to TRK inhibition can be dramatic and durable, duration of response may eventually be limited by acquired resistance. LOXO-195 is a selective TRK TKI designed to overcome acquired resistance mediated by recurrent kinase domain (solvent front and xDFG) mutations identified in multiple patients who have developed resistance to TRK TKIs. Activity against these acquired mutations was confirmed in enzyme and cell-based assays and in vivo tumor models. As clinical proof of concept, the first 2 patients with TRK fusion-positive cancers who developed acquired resistance mutations on larotrectinib were treated with LOXO-195 on a first-in-human basis, utilizing rapid dose titration guided by pharmacokinetic assessments. This approach led to rapid tumor responses and extended the overall duration of disease control achieved with TRK inhibition in both patients.Significance: LOXO-195 abrogated resistance in TRK fusion-positive cancers that acquired kinase domain mutations, a shared liability with all existing TRK TKIs. This establishes a role for sequential treatment by demonstrating continued TRK dependence and validates a paradigm for the accelerated development of next-generation inhibitors against validated oncogenic targets. Cancer Discov; 7(9); 963-72. ©2017 AACR.See related commentary by Parikh and Corcoran, p. 934This article is highlighted in the In This Issue feature, p. 920.

How Can Physicians Educate Patients About Health Care Policy Issues?

Complicated health care policy decisions are generally made by elected officials. The officials making these complicated decisions are elected by the people, and citizens' participation in the voting process is one of the basic tenets of democracy. Voters in the United States, who are also patients in the health care system, receive enormous amounts of information throughout election cycles. This information is generally delivered in sound bites often intended to elicit an emotional reaction rather than simply inform. From April through July 2016, the author-an academic physician-rode a bicycle across the United States and met with people in small rural towns to ask them their understanding of the Affordable Care Act and the impact it has had on their lives. In this Commentary the author shares some of those stories, which are often informed by sound bites and misinformation. The author argues that it is the role of academic physicians to educate not only students and residents but also patients. In addition to providing information about patients' medical problems, physicians can educate them about the health care policy issues that are decided by elected officials.A doctor can help educate patients about these issues to facilitate their making informed decisions in elections. Physicians have a role and responsibility in society as a knowledgeable person to make the health care system be the best it can be for the most people.

Using standardized patients to evaluate medical students' evidence-based medicine skills

OBJECTIVES

To analyze the effectiveness of an Evidence Based Medicine Objective Structured Clinical Examination (EBM OSCE) with standardized patients for end of third year medical students at our institution.

METHODS

This was a single-center prospective cross-sectional investigation. As part of the eight-station OSCE exam, the authors developed and implemented a new 25-minute EBM OSCE station with the goal of evaluating evidence based medicine skills necessary for daily clinical encounters. The OSCE case involved a highly educated patient with a history of recurrent debilitating migraines who has brought eight specific questions regarding the use of steroids for migraine headaches. Students were provided computer stations equipped to record a log of the searches performed.

RESULTS

One hundred and four third-year medical students participated in this study. The average number of search tools used by the students was 4 (SD = 2). The 104 students performed a total of 896 searches. The two most commonly used websites were uptodate.com and google.com. Sixty-nine percent (95% CI, 60% to 78%) of students were able to find a meta-analysis regarding the use of dexamethasone for the prevention of rebound migraines. Fifty-two percent of students were able to explain that patients who took dexamethasone had a moderate RR (0.68 to 0.78) of having a recurrent migraine, and 71% of students were able to explain to the standardized patient that the NNT for dexamethasone was nine.

CONCLUSION

The EBM OSCE was successfully integrated into the existing eight-station OSCE and was able to assess student EBM skills.

KnowPain-50: a tool for assessing physician pain management education

BACKGROUND

Despite a need for better physician pain management education, there are no widely accepted assessment or outcome measures to support this work.

OBJECTIVE

Create a self-assessment tool to measure physician educational needs and the effectiveness of chronic pain educational programs.

DESIGN

We used expert consensus to draft a 142-item survey that covered essential areas of chronic pain management. We tested the survey in 106 physicians, including 22 pain management experts and used predefined psychometric criteria to eliminate 70 items. We then eliminated 22 remaining items that did not correlate with the management of a standardized chronic pain patient by 27 academic physicians. We evaluated internal consistency using Cronbach's alpha.

RESULTS

The final 50-item survey assessed physician knowledge, attitudes, and beliefs in: 1) initial pain assessment; 2) defining goals and expectations; 3) development of a treatment plan; 4) implementation of a treatment plan; 5) reassessment and management of longitudinal care; and 6) management of environmental issues. The survey demonstrated good internal consistency in all physician populations studied (alpha = 0.77-0.85). Average scores in 84 "pilot" physician users of a CME Website (135.8-138.5) were significantly lower (P < 0.01) than scores in 27 academic physicians (150.0), or 22 pain experts (177.5).

CONCLUSIONS

This survey, the KnowPain-50, has good psychometric properties, correlates with clinical behaviors, and appears to distinguish between physicians with different levels of pain management expertise. It may be a useful measure of the effectiveness of physician pain management education programs.

The variable response of women with menopausal hot flashes when treated with sertraline

OBJECTIVE

To evaluate the variable response of women when treated with a selective serotonin reuptake inhibitor (sertraline) to decrease hot flashes.

DESIGN

A double-blind, placebo-controlled, crossover trial was conducted in 102 women aged 40 to 65 years who were experiencing hot flashes and not taking any hormone therapy. The original purpose of the study was to evaluate the effectiveness of sertraline for the treatment of hot flashes. After 1 week of baseline hot flash data collection, study participants were randomized to receive placebo or active drug (sertraline 50 mg) for 4 weeks. This intervention was followed by a 1-week washout and crossover to the opposite treatment for 4 weeks. The number and severity of hot flashes were measured.

RESULTS

One hundred two women were enrolled in the study, and 87 completed the study. The average response was a statistically significant but clinically modest reduction in hot flash frequency and hot flash index (frequency x severity). These data on the average response have been previously published. Although the average response was modest, some women responded vigorously, others modestly, and some women actually worsened. This is a post hoc analysis of those data. Percentage of change was divided into three categories of clinical response: women with a clinically significant reduction (>or=30%, n=27), women with a nonsignificant reduction (<30% to none, n=28), and women with an increase (1%-100%, n=32). A vigorous response to sertraline for the treatment of hot flashes was related to activity level, education, and menopausal status.

CONCLUSIONS

Women have markedly variable responses when treated with antidepressants for their hot flashes. We have begun to describe the characteristics of those most likely to respond to treatment with a selective serotonin reuptake inhibitor.

Sertraline to treat hot flashes

OBJECTIVE

To evaluate the effectiveness of a selective serotonin reuptake inhibitor (SSRI) (sertraline) in decreasing hot flashes in a general population of women.

DESIGN

A double-blind, placebo-controlled, crossover trial was conducted in a southwestern urban setting. A total of 102 women aged 40 to 65 who were experiencing hot flashes and not taking any hormone therapy were recruited. After 1 week of baseline hot flash data collection, study participants were randomized to receive placebo or active drug (sertraline 50 mg) for 4 weeks. This intervention was followed by a 1-week washout and cross over to the opposite treatment for 4 weeks. The number and severity of hot flashes were measured.

RESULTS

One hundred two women were enrolled in the study. Five dropped out before providing baseline data. Of the 97 remaining, 52 were randomized to active drug first and 45 to placebo first. Ten dropped out of the study before completing all 10 weeks, leaving 46 in the active drug-first arm and 41 in the placebo-first arm. At baseline, the mean number of hot flashes reported was 45.6 per week (SD = 29.6), ranging from 2 to 148. During the sertraline phase of the study, women experienced five fewer hot flashes per week than they did on the placebo (P = 0.002). The severity of hot flashes was not significantly different; however, the hot flash score (number x average severity) was significantly improved during the sertraline phase.

CONCLUSION

Sertraline reduced the number of hot flashes and improved the hot flash score relative to placebo and may be an acceptable alternative treatment for women experiencing hot flashes.

Thoughts on communication

Living without the ability to communicate is humbling. Time spent on a sabbatical in Florence, Italy, taught me that my outgoing manner, my interactional skills, and my ability to establish rapport, all personality traits and skills that I thought would overcome my inadequacies as a communicator in Italian are not immutable. I gained some understanding of what our nonnative English-speaking patients might feel. I learned the following lessons: (1) be cautious-what appears to be a lack of interest may be a lack of understanding; (2) our perceptions of aptitude may be mistaken if based on patients' facial expressions and body language; (3) we should not adjust our words and speed of speech just because we think a patient cannot understand what we are saying; and (4) language is an amazingly powerful tool-the inability to communicate transforms us.

Biology and plasticity of CD133+ hematopoietic stem cells

AC133 (CD133) is a highly conserved antigen expressed on hematopoietic stem cells with unknown function. In order to further characterize CD133(+) progenitor cells, we purified CD133(+) stem cells using the method of magnetic activated cell sorting (MACS) from healthy adult volunteers mobilized with granulocyte colony-stimulating growth factor (G-CSF) to a mean purity of 94%. The purified CD133(+) cells highly engrafted NOD/SCID mice. In addition, unseparated mononuclear cells or CD133(+) stem cells isolated from the bone marrow of transplanted NOD/SCID mice gave rise to engraftment of secondary recipients. Upon ex vivo culture of purified CD133(+) cells with FLT3/Flk2 ligand (FL) and interleukin-6 (IL-6), a plastic-adherent cell population could be observed after 6 weeks in culture. These adherent cells did not express CD34 or CD133 antigens on their surface, nor did they express markers for endothelial, mesenchymal, or dendritic cells. After incubation of these adherent cells with stem cell factor (SCF), non-adherent cells were observed which partially co-expressed CD133, but were negative for CD34. These nonadherent CD34(-) cells showed a high engraftment capacity in NOD/SCID mice. From our results, we conclude that CD133 might be a marker of early progenitors with a high NOD/SCID engraftment potential. The fact that CD133(+) hematopoietic progenitors can give rise to an adherent population which is CD133(-) and CD34(-) and that these cells can again give rise to a CD133(+)CD34(-) stem cell population with high NOD/SCID engraftment potential indicates the plasticity of hematopoietic precursors. CD133(+) stem cells might be useful for research and for clinical application.

Large-scale isolation of CD133+ progenitor cells from G-CSF mobilized peripheral blood stem cells

We have evaluated the feasibility of large-scale isolation of CD133+ progenitors from healthy mobilized adult donors for potential clinical use in autologous and allogeneic transplantation. A total of 11 healthy volunteer adult donors were mobilized with G-CSF. CD133+ stem cells were isolated from a single leukapheresis using the Clinimacs method. The median percentage of CD133 before positive selection was 0.75% (range 0.39-2.03%). After selection, the median purity and recovery was 94% (range 85.2-98.0%) and 69% (range 44-100%), respectively. The median log10 T-cell depletion obtained by CD133+ positive selection was 4.2 (range 3.8-4.7). The CD133+ progenitors were highly enriched in colony-forming units (CFU) and transplantation into NOD/SCID mice resulted in a high engraftment rate. Transplantation of sorted CD133+/CD34+ cells into NOD/SCID mice showed a higher engraftment compared to CD133-/CD34+ cells. Mobilized peripheral CD133+ stem cells can be purified in large scale for potential clinical use. The biological function of the cells is not impaired. The majority of the NOD/SCID repopulating cells are within the CD133+/CD34+ subpopulation. Therefore, clinical studies using purified CD133+ stem cells can be envisoned to further clarify the role of CD133+ stem cells in hematopoietic reconstitution after transplantation.

A large-scale method for T cell depletion: towards graft engineering of mobilized peripheral blood stem cells

We have investigated the feasibility and efficacy of large-scale T cell depletion from granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cells (PBSC). The method is based on the use of a CD3 antibody conjugated to magnetic microbeads and magnetic activated cell sorting (Clinimacs). A total of eight large-scale experiments were performed. In four experiments, CD3(+) T cells were depleted from PBSC obtained from volunteers mobilized with G-CSF whereas, in four experiments, T cells were depleted from PBSC from stem cell donors, in which the CD34(+) stem cells had been removed for allogeneic transplantation by positive selection prior to T cell depletion. The mean number of processed mononuclear cells (MNCs) was 3.3 x 10(10) (range 1.5 x 10(10)-5.1 x 10(10)) with a mean T cell proportion of 35.8% (range 16.7-64.0%). After T cell depletion, the percentage of contaminating T cells was 0.15% (range 0.01-1.01%) with a mean log(10) depletion of 3.4 (range 2.8-4.1). The mean recovery of CD3-negative MNCs after depletion was 76% (range 52-100%). The mean recovery of CD34(+) stem cells in the four evaluable experiments was 82% (range 75-92%). In vitro colony assays and in vivo NOD/SCID repopulation assays showed that this large-scale T cell depletion method has no negative impact on the function of the hematopoietic precursor cells. Therefore, we conclude that this T cell depletion method is a valuable tool for further graft engineering strategies involving mobilized PBSCs.

Effect of an integrated nutrition curriculum on medical education, student clinical performance, and student perception of medical-nutrition training

BACKGROUND

Ninety-eight percent of medical schools report nutrition as a component of medical education. However, most schools do not have an identifiable nutrition curriculum. Medical schools that do include nutrition have not evaluated its effect on clinical skills.

OBJECTIVE

The objective was to determine the efficacy of an integrated undergraduate medical curriculum to increase the quantity of nutrition instruction and to advance nutrition clinical skills demonstrated by medical students.

DESIGN

A quasiexperimental design was constructed to determine whether an integrated nutrition curriculum increased the performance on nutrition-oriented clinical examinations of medical school classes that received 1, 2, or 3 y of the curriculum. The evaluation of the curriculum focused on 3 areas: 1) hours of nutrition instruction, 2) the application of nutrition within a clinical setting, and 3) perceptions about the nutrition curriculum. The Objective Structured Clinical Examination (OSCE) nutrition score was compared between graduating classes by use of analysis of variance. Data from the American Association of Medical Colleges were analyzed to determine the change in the proportion of students who reported that the amount of time devoted to nutrition was adequate.

RESULTS

The implementation of the integrated nutrition curriculum resulted in a doubling of the total hours of required instruction in the medical curriculum (35 compared with 75 h). The mean (+/-1 SEM) OSCE nutrition score significantly improved after the implementation of the curriculum (41.7 +/- 0.9% compared with 50.6 +/- 1.1%) and the percentage of students who reported that the amount of nutrition taught during medical school was inadequate decreased (68.4% compared with 11.5%).

CONCLUSION

Medical students improved their clinical nutrition practice skills through participation in an integrated nutrition curriculum.

Using problem-based learning to promote critical thinking in an orientation program for novice nurses

To assist novice nurses in making the transition into the acute care setting, a student-centered, small-group, problem-based program was developed and combined with a preceptorship program. Challenged to work through the problems, novice nurses met the program objectives while enjoying the program. Supervisors and clinical specialists working with the graduates noted increased critical thinking, increased interest and ability in seeking information, and increased problem-solving ability.

Atypical infective endocarditis

BACKGROUND

Although infective endocarditis has changed in the recent past as a result of microbiologic and risk factors, it continues to be clinically challenging. The disease is characterized by the formation of septic masses of platelets on the surfaces of heart valves. Several mechanisms can cause or contribute to the development of endocarditis. Although risk factors for infective endocarditis are well known, patients with atypical signs and symptoms continue to challenge us.

METHODS

We describe a case report of a patient admitted to our inpatient service with back pain and presumed pyelonephritis. A MEDLINE literature search was conducted, using the key words "endocarditis," "back pain," and "bacterial," for the years 1986 to the present.

RESULTS AND CONCLUSIONS

A 42-year-old woman with a history of intravenous drug abuse was admitted to the family practice service with back pain and pyelonephritis. She developed hypoxia and a new heart murmur and had continued fevers. Blood cultures drawn in the emergency department grew methicillin-resistant Staphylococcus aureus. A bone scan and magnetic resonance imaging led to the diagnosis of epidural abscess. What appeared to be a simple case of pyelonephritis with back pain became a case of infective endocarditis complicated by an epidural abscess.

Teams in a community setting: the AUHS experience

The Pennsylvania Local Interdisciplinary Team was created to develop and implement an innovative model for the education of students from multiple disciplines and institutions in the theory and practice of quality improvement. The lead poisoning prevention project is presented as an example of the work of an interdisciplinary student team in a community setting in Philadelphia.

A multisite collaborative for the development of interdisciplinary education in continuous improvement for health professions students

In 1994, The Institute for Healthcare Improvement, in Boston, Massachusetts, formed the Interdisciplinary Professional Education Collaborative (the Collaborative). The mission of the Collaborative is to create an interdisciplinary teaching and learning environment in which future health professionals learn to work together to improve health care delivery. Apart from emphasizing interdisciplinary collaboration, the Collaborative focuses on teaching the methods of continuous improvement (CI), a system of management first developed for manufacturing industries that is increasingly being used in the management of health care delivery. The Collaborative consists of four local interdisciplinary teams (LITs): the Cleveland LIT, the "George" LIT (a collaboration between George Washington University in Washington, D.C., and George Mason University in Fairfax, Virginia), the South Carolina LIT, and the Pennsylvania LIT; and a coordinating committee. This paper describes each LIT's approach to achieving the Collaborative's commitment to give health professions students the opportunity to work in interdisciplinary teams to learn about and practice CI methods, training the Collaborative believes will enable them to be effective providers in a variety of health care systems. The paper describes the overall goals of the Collaborative, presents reports from the four LITs, and discusses common lessons learned.

Mammography and Pap smear screening of Yaqui Indian women

The Pascua-Yaqui Tribe of Arizona receives its health care services at a local neighborhood health center in Tucson and a satellite clinic located on the reservation. Using a computerized data base from the health center, the authors determined the use rates by Pascua-Yaqui women ages 35-65 of the Papanicolaou smear and mammography screening. Among active users of the health center, 31-36 percent had received a Papanicolaou smear, according to the yearly data bases examined from 1986 to 1990, while 65 percent of the women had received at least one smear test over the entire 5-year period. Regarding mammography screening, 41-43 percent of the women ages 50-65 had received a mammogram in the years studied, and 51-58 percent of the women ages 40-49 had been screened. In all, 67 percent had received at least one mammogram during the 1988-90 period when the center offered mammography. This population of 35-65-year-old American Indian women, for whom financial access is not a barrier, were receiving Papanicolaou smears and mammograms at rates comparable with other segments of the U.S. population but at lower rates than those recommended by the American Cancer Society and National Cancer Institute. The challenge for the health center is to reach those women who are eligible for services but do not use them and to address the nonfinancial barriers to care such as language, transportation, and gender-specific issues.

The service-education linkage: implications for family practice residency programs and community and migrant health centers

INTRODUCTION

Access to quality primary health care for our country's underserved populations is a challenge for both the government and physicians. The Division of Medicine, through funding priorities and other initiatives, is encouraging family practice educators to train residents and students for work in community and migrant health centers (C/MHCs) in underserved areas. The objective of this research was to study linkages between family practice residency programs and C/MHCs and determine the reasons for affiliation, disadvantages and advantages, predictors of successful linkages, and common errors in the linkage agreement.

METHODS

We conducted in-depth telephone interviews with the directors of 13 of the 19 family practice residency programs identified as having linkages with C/MHCs.

RESULTS

All interviewees at residency programs indicated that their programs had a mission to serve underserved patients. The most commonly cited constraining factor cited by both residency programs and C/MHCs was financial support for residents, on-site faculty, and support staff. Many programs reported that residents training at the C/MHC were able to gain a community health perspective and practice community-oriented primary care. Finally, financing the relationship involved many different approaches, ranging from the residency paying all of the salaries, to a sharing of salaries by the residency, state, and/or hospital, to C/MHC paying the salaries either through its own funds or through grant support.

DISCUSSION

These data provide an assessment of the current issues that family practice residencies must address to implement service-education linkages. They provide an empirical basis to outline the steps involved in forming a linkage between a residency and a C/MHC.

Cytoskeletal events underlying dendrite formation by cultured pigment cells

In contrast to neurite outgrowth, pigment cell dendrite formation is relatively unstudied. Keratinocyte-conditioned medium (KCM) induces a striking dendricity in human melanocytes and B16 melanoma cells that is detectable within 30 min, maximal in 24-48 hr, and quantifiable by computerized image analysis. Cytochalasin B (CB), known to disrupt actin microfilaments, completely blocks dendrite formation if added to cultures before or with KCM. This effect is rapidly reversible, and dendrites appear within 1 hr after refeeding with KCM alone. In contrast, CB treatment fails to disrupt existing dendrites previously induced by KCM. Agents known to cause microtubule disassembly (colchicine, nocodazole, or vinblastine) do not inhibit dendrite formation if added before or with KCM. In contrast, these agents disrupt established dendrites. Inhibition of protein synthesis with cycloheximide or actinomycin D completely blocks dendrite formation, but if cultures are provided fresh KCM lacking protein synthesis inhibitors, dendrites reappear within 24 hr. Actin microfilaments visualized with a monoclonal antibody or rhodamine-phalloidin are poorly organized in untreated cells, but form numerous fibers localized along dendrites in KCM-treated cells. Microtubules visualized with a monoclonal anti-tubulin antibody are localized in the center of dendrites. These cytoskeletal changes occur without altering beta actin or beta tubulin mRNA levels. Taken together, these data implicate actin microfilaments in dendrite outgrowth, but not in maintenance, and conversely microtubules in dendrite maintenance but not in formation. These keratinocyte-induced changes involving beta actin and beta tubulin polymerization appear to require both new protein synthesis and post-translational regulation. The observed similarities between melanocytes and other neural crest-derived cells suggest that cutaneous pigment cells might serve as an alternative model for studies of neurite outgrowth.

Family physicians' colposcopy practices

BACKGROUND

The objectives of this study were to determine (1) the extent to which family physicians are performing colposcopy, (2) which colposcopic procedures are performed by these family physicians, (3) demographic characteristics of physicians who perform colposcopy, and (4) whether physicians who do not perform colposcopy plan to do so in the future.

METHODS

A questionnaire was mailed to all 757 self-identified family practice physicians in Arizona.

RESULTS

The return rate was 72 percent, and the response rate was 55.5 percent. Results indicated that 19.3 percent of respondents were trained to perform colposcopy, and 9.5 percent actually have performed it. For those performing colposcopy, the mean number of procedures performed during the previous 6 months was 25 (range 2-100).

CONCLUSIONS

Certain barriers to performing colposcopy were identified: (1) lack of available training, (2) interspecialty "turf battles," (3) quality assurance, and (4) the cost of malpractice liability insurance. Nevertheless, there were no insurmountable reasons why family physicians could not perform colposcopy.

Pigment content of cultured human melanocytes does not correlate with tyrosinase message level

Tyrosinase is considered to be the rate-limiting enzyme for the biosynthesis of melanin in epidermal melanocytes, and thus tyrosinase activity is thought to be a major regulatory step in melanogenesis. To determine whether the rate of pigment production was controlled at the level of tyrosinase gene expression, we developed a culture system capable of generating large populations of pure human melanocytes and then measured both melanin content as determined spectrophotometrically by absorption at 475 nm and mRNA levels as detected by hybridization with cloned cDNA Pmel 34, encoding human tyrosinase. We examined the relationship between pigment content and tyrosinase mRNA levels among human melanoma and melanocyte lines with very different levels of basal pigmentation; between two clones of a single human melanoma line, one pigmented and one amelanotic; and sequentially in melanocytes before and after simulation with isobutylmethylxanthine to increase melanin content per cell. Using Northern blot analysis and in-situ hybridization we found no correlation between tyrosinase message levels and melanin content, suggesting that posttranscriptional regulation of tyrosinase and/or other events determine the rate of pigment synthesis in human melanocytes.

Cancer risk reduction counseling: a computer-assisted curriculum

Significant progress has been made in the identification of factors associated with an increased risk of developing cancer. Cancer is increasingly viewed as a preventable disease. Its prevention involves risk reduction counseling. This counseling is an important skill for the family physician but can be difficult to learn and to teach. We used a prototype, computer-assisted cancer risk reduction counseling curriculum with first-year medical students. We found a statistically significant change in both knowledge-based and attitudinal questions and answers after the use of this curriculum.

A microcomputer-based device to simulate biomechanical environments for cultured cells

We describe software and hardware for a microcomputer-based cyclic strain device which applies programmed cycles of elongation and relaxation to cultured cells. This system has the potential to simulate many of the complex mechanically active environments found in living systems. As a sample application, we use it to simulate the cyclic stresses to which vascular smooth muscle cells in the arterial system are exposed.

Phenolic and tyrosyl ring iodothyronine deiodination by the Caco-2 human colon carcinoma cell line

Thyroid hormone metabolism was studied in the human Caco-2 colon carcinoma cell line, which at confluence exhibits several functions of differentiated enterocytes. Cells were harvested two to 17 days after reaching confluence. Intact cells and homogenates were tested for deiodination of [125I]-labeled substrates. Small amounts of thyroxine (T4) were converted by homogenates to 3,3',5'-triiodothyronine (rT3), 3,3'-diiodothyronine (3,3'-T2), and 1-, with no detectable production of 3,5,3'-triiodothyronine (T3) by homogenates or cells. rT3 was converted to 3,3'-T2 and 1- with an apparent Michaelis constant (Km) for rT3 of 24 nmol/L; 6-n-propyl-2-thiouracil (PTU) had a 50% inhibitory concentration of 30 nmol/L and abolished rT3 5'-deiodination at 1 mmol/L in the presence of 20 mmol/L dithiothreitol (DTT). T3 was deiodinated to 3,3'-T2 and 3'-monoiodothyronine (3'-T1) with an apparent Michaelis constant (Km) for T3 of 5.7 nmol/L; this reaction was not inhibited by 1 mmol/L PTU. Phenolic and tyrosyl ring deiodinating activities were maximal four and six days, respectively, after the cells reached confluence. Homogenates of cells grown in standard medium containing fetal calf serum had fivefold higher rT3 5'-deiodinating activity than cells grown in a serum-free defined culture medium, reflecting a fivefold difference in the apparent Vmax with no difference in the apparent Km for rT3. There was no difference in T3 5-deiodination rates in homogenates of Caco-2 cells grown in the two media until 12 days postconfluence, when cells grown in standard medium had higher activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Human melanogenesis is stimulated by diacylglycerol

The intracellular signal pathways that mediate pigmentation in human skin are unknown. We now report that a diacylglycerol (DAG) analogue 1-oleoyl-2-acetyl-glycerol (OAG) 25-100 microns strikingly increased the melanin content of cultured human melanocytes in a dose dependent manner without altering growth rate. The pigment increase occurred within 24 h, was accompanied by increased incorporation of the melanin precursor L-3,4-dihydroxyphenyl alanine (DOPA), required new protein synthesis, and was completely blocked by the protein kinase C (PKC) inhibitors H-7 and sphingosine. A PKC-inactive DAG isomer had no effect on melanin per cell. These results implicate protein kinase C and its effector DAG in melanogenesis.

Regulation of human melanocyte growth, dendricity, and melanization by keratinocyte derived factors

Epidermal pigmentation involves the synthesis of melanin in melanocytes and its transfer to surrounding keratinocytes, where it functions in photoprotection. To investigate the possible role of the keratinocyte in regulating pigmentation, human keratinocytes were incubated for 24 h in a defined culture medium, which was then transferred to pure human melanocyte cultures. After 1 week, the conditioned medium produced a fourfold increase in melanocyte yield and a seven-fold increase in total melanin. Increased melanocyte dendricity was clearly visible within 24 h as well. Ultrafiltration of the keratinocyte-conditioned medium suggested approximately one-half of the growth promoting activity as well as most of the dendricity and melanization stimulating activities were of low molecular weight (less than 500 Da). High molecular weight fractions stimulated only melanocyte growth. Of the several known keratinocyte-derived factors tested, none could be implicated as a mediator of the observed effects. Basic fibroblast growth factor, known to stimulate melanocyte growth in some culture systems, failed to stimulate growth, dendricity, or melanin content when added to the complete non-conditioned medium. Interleukin-1 alpha, interleukin-1 beta, 12-hydroxyeicosatetraenoic acid, prostaglandin E2, leukotriene B4, and adenosine 3',5'-cyclic monophosphate analogues also had no effect. These studies demonstrate that keratinocytes in vitro release factors that modulate melanocyte behavior and expand our understanding of controls for human epidermal pigmentation.

Demonstration of a choline requirement for optimal keratinocyte growth in a defined culture medium

Nutrient requirements for proliferation and differentiated function of individual cell types can be determined using cell culture methodologies. Human epidermal keratinocytes are stimulated to grow by choline supplementation in the presence of myo-inositol when grown in a commercial nutrient medium containing six other defined supplements. The optimal range of choline concentrations varied among donor cell lines, but consistently fell between 36 microM and 180 microM. Addition of 72 microM choline increased cell yield to 250 +/- 38% of that produced by myo-inositol supplementation alone and 92 +/- 8% of that produced by addition of a highly mitogenic hypothalamic extract, which was previously required for good growth in this culture system. Supplementation of the basal medium with both the extract and choline resulted in 165 +/- 13% of the cell yield observed with the extract addition alone. Supplementation with other phospholipid precursors did not further increase keratinocyte growth. Neither dermal fibroblasts nor epidermal melanocytes were stimulated by supplementation with choline, suggesting the high keratinocyte requirement is unusual. This completely defined culture medium for keratinocyte growth should prove useful in analyzing the role of phospholipids and other nutrients in human epidermis.

Vitamin D, its precursors, and metabolites do not affect melanization of cultured human melanocytes

Exposure of the skin to sunlight results in both tanning and vitamin D3 production. It has therefore been suggested that vitamin D3 or its active metabolite 1,25-dihydroxyvitamin D3 may be the mediator of UV-induced melanogenesis. To test this hypothesis, newborn foreskin-derived melanocytes were cultured in paired dishes in hormone-supplemented medium with 2% serum containing no detectable vitamin D3 or in the same medium containing 10(-8) or 10(-10) M of either provitamin D3, lumisterol, previtamin D3, vitamin D3, 25-hydroxyvitamin D3, or 1,25-dihydroxyvitamin D3. After 10 days, cell number in cultures containing vitamin D compounds was 93%-140% of unsupplemented controls and melanin content was 60%-120% of control, with no significant difference in either parameter for any compound tested. In separate experiments, human melanocytes and Cloudman S91 melanoma cells were repeatedly irradiated with physiologic doses of simulated sunlight and incubated between irradiations with provitamin D3, previtamin D3, vitamin D3, or 1,25-dihydroxyvitamin D3. Irradiated cultures had a 90%-95% inhibition of cell growth associated with a 200%-800% increase in melanin content per cell relative to controls, but there was no effect of any vitamin D compound on either cell type. Neither cultured human melanocytes nor S91 cells showed evidence of the cytosolic 1,25-dihydroxy-vitamin D3 receptor binding by sucrose density gradient analysis using radiolabeled 1,25-dihydroxyvitamin D3. The combined data strongly suggest that neither vitamin D3 nor its precursors or metabolites directly mediate melanogenesis in these cells.

Inositol is a required nutrient for keratinocyte growth

Bovine hypothalamus is known to contain a growth-promoting activity for human epidermal keratinocytes. By sequential purification, the substance was isolated and found to be myo-inositol. The identity of the substance as myo-inositol was confirmed by ion modified partition, gas liquid, thin layer chromatography, by mass spectrometry, and quantitative bioassay. The inositol content of the crude hypothalamic extract and of an active acetone precipitate (the first step in the purification) was determined to be sufficient to account for their observed bioactivity. At an optimal concentration of 55 microM (10 micrograms/ml), myo-inositol approximately tripled keratinocyte yield compared to paired cultures in basal medium containing 0.3 microM, although this yield was only half that produced by a crude saline extract of hypothalamus, suggesting that there are additional growth-promoting activities in the tissue extract. No other skin-derived cell type tested was stimulated by supplemental inositol. These results establish that the inositol requirement for cultured human keratinocytes is markedly higher than for any other normal or malignant cell type investigated to date, and expand the list of brain-derived phospholipid precursors known to stimulate epithelial proliferation in vitro. These data suggest that inositol may subserve quantitatively or qualitatively different functions in the keratinocyte than in other cell types.

Human epidermal keratinocytes in culture convert thyroxine to 3,5,3'-triiodothyronine by type II iodothyronine deiodination: a novel endocrine function of the skin

Cultured human keratinocytes converted T4 to T3 by type II iodothyronine deiodination. Homogenates of keratinocytes cultured from neonatal foreskin or adult arm skin had similar mean T4 5'-deiodinating activities. Conversion of T4 to T3 by intact cells was demonstrable in cultures from neonatal and adult donors. Only phenolic ring deiodination occurred in the cultured cells and their homogenates, the apparent Michaelis constant for T4 was 12 nmol/L, and T4 and rT3 each inhibited 5'-deiodination of the other. T4 5'-deiodination was unaffected by addition to the assay mixture of 1 mumol/L T3, but was inhibited less than 10% by 1 mmol/L 6-n-propyl-2-thiouracil, 50% by 270 nmol/L iopanoic acid, 50% by 9.4 mumol/L 3,5-diiodo- 3',5'-dimethyl-L-thyronine, and 33% by 42 mumol/L amiodarone. When keratinocytes were cultured for 3-4 days in medium containing iodothyronine-free fetal calf serum, the T4 5'-deiodination rates in homogenates doubled; this increase was prevented by restoring a physiological free T4 concentration, but not by a supraphysiological T3 concentration. Homogenates of fresh whole skin or fetal cadaveric epidermis did not convert T4 to T3 in measureable amounts, although one epidermal homogenate had low level T3 typrosyl-ring deiodinating activity. These results suggest that human epidermal type II iodothyronine deiodination in man might conceivably contribute to the intracellular T3 content of the skin and even to serum T3 concentrations, especially in hypothyroidism.

Effects of iron-, manganese-, or magnesium-deficiency on the growth and morphology of Euglena gracilis

Iron-, manganese-, or magnesium-deficiency has been induced in Euglena gracilis. Each arrests cell proliferation, decreases the intracellular content of the deficient metal, and increases that of several other metals. Light and electron microscopy of stationary phase cells reveal that Fe-deficient (-Fe) cells are similar in size and shape to control organisms. Magnesium-deficient (-Mg) cells, however, are larger, and approximately 14% are multilobed, containing 2 to 12 lobes of equal size emanating from a central region. Individual (-Mg) cells and each lobe of multilobed cells contain a single nucleus. Manganese-deficient (-Mn) organisms are morphologically more heterogeneous than (-Fe) or (-Mg) cells. Most are spherical and larger than controls. Approximately 15% are multilobed but, unlike (-Mg) cells, contain lobes of unequal size with either zero, one, or several nuclei present in each. Nuclei of (-Mn) cells differ in size and shape from those of control, (-Fe), or (-Mg) cells. All three deficient cell types accumulate large quantities of paramylon. Other cytoplasmic structures, however, appear normal. Addition of Fe, Mn, or Mg to the respective deficient stationary phase cultures reverses growth arrest and restores normal morphology. The results suggest that Fe-, Mn-, and Mg-deficiencies affect different stages of the E. gracilis cell cycle.

Pericatheterization risk factors in left main coronary artery stenosis

Patients with left main (LM) coronary artery disease (CAD) have an unexplained high incidence of complications during diagnostic cardiac catheterization. This study identifies pericatheterization risk factors for major complications in patients with LM CAD (stenosis at least 50%). Complications were defined as ventricular fibrillation not related temporally to coronary injection, persistent angina, acute myocardial infarction, profound hypotension and death during or within 24 hours of catheterization. One hundred seven consecutive cases of LM CAD (11 with complications and 96 without) were reviewed with respect to variables potentially related to complications. Patients who had angina in the 24 hours before catheterization were at increased risk. Four of 13 patients with angina (31%) and 7 of 94 (7%) without angina had complications (p less than 0.05). Distance from the catheter tip to the lesion also was related to complications (9 of 38 [24%] with tip 6.0 mm or less from lesion and 2 of 65 [3%] with tip more than 6.0 mm from lesion, p less than 0.05). No relaxation was found between complications and New York Heart Association functional class, technique (femoral vs brachial), performance of ventriculography, number of coronary injections, amount of contrast injected, severity of LM stenosis, number of major arteries with 75% or more diameter stenosis, mean arterial pressure, left ventricular end-diastolic pressure and left ventricular ejection fraction.

Relative responsiveness of cultured human epidermal melanocytes and melanoma cells to selected mitogens

Early cellular events in the malignant transformation of melanocytes to melanoma are virtually unknown. In vitro investigation of this phenomenon has been hampered by the fastidious nature of the human epidermal melanocyte, which has proven difficult to cultivate. The present study compares responsiveness of cultured human epidermal melanocytes and established melanoma cell lines to serum, cholera toxin, and melanocyte growth factor (MGF), three established melanocyte mitogens. Four of four established human melanoma lines were substantially stimulated by fetal bovine serum, as were newborn foreskin-derived epidermal melanocytes. In contrast, none of the four melanoma lines responded to hypothalamic preparations containing MGF that consistently produced an approximately 30-fold increase in newborn melanocyte cell yield over a 2-week period. Cholera toxin, required for successful establishment of primary melanocyte cultures, had small and variable effects on the melanoma lines, with slight stimulation in one case, moderate inhibition in another, and essentially no effect in two others. These data suggest that transformation of epidermal melanocytes to melanoma often involves at least one phenotypic change resulting in escape from MGF regulation and another associated with insensitivity to cyclic AMP modulation; while at least some of the pathways conferring serum dependence are unaltered. Improved culture systems for the human epidermal melanocyte should facilitate further studies into the mechanism of its malignant conversion and may provide useful insights for the prevention and treatment of human melanoma.

Euglena gracilis chromatin: comparison of effects of zinc, iron, magnesium, or manganese deficiency and cold shock

The effects induced by Fe, Mn, or Mg deficiency or cold shock on the DNA content and histones of Euglena gracilis have been examined and compared to those produced by Zn deficiency. The DNA content of the stationary-phase organisms used as controls is 2.1 micrograms/10(6) cells. The DNA of stationary-phase iron-deficient (-Fe), magnesium-deficient (-Mg), manganese-deficient (-Mn), zinc-deficient (-Zn), and cold-shocked (CS) cells is increased to 3.0, 4.6, 6.2, 3.8, and 3.8 micrograms/10(6) cells, respectively. The electrophoretic mobilities of proteins solubilized with 0.4 N H2SO4 from CS, -Fe, -Mg, and -Mn cells are nearly identical and are characteristic of the five histone classes, H1, H2A, H2B, H3, and H4. In contrast, no histones are found in the equivalent acid extract from -Zn cells. The effect of micrococcal nuclease on chromatin from control, CS, and -Zn cells was examined. The chromatin of CS cells is 1.2-fold while that from -Zn cells is 10-30-fold more resistant to micrococcal nuclease digestion than is the chromatin of control cells. Thus, the chromatin of cells grown in Zn-deficient conditions differs markedly from that of organisms cultured in media deficient in Fe, Mn, or Mg or exposed to cold shock.

Load regulation of the properties of adult feline cardiocytes. The role of substrate adhesion

We have recently described rapid and reversible changes in cardiac structure, function, and composition in response to surgical load alteration in vivo. In the present study, we used a simple, well-defined in vitro experimental model system, consisting of terminally differentiated quiescent adult cat ventricular cardiocytes maintained in serum-free culture medium, to assess more definitively the role of loading conditions in regulating these same biological properties of heart muscle. Cardiocytes considered to be externally loaded were adherent throughout their length to a protein substrate, such that the tendency for the ends of the cells to retract was prevented. Cardiocytes considered to be unloaded were not adherent to a substrate and, thus, were free to assume a spherical shape. Cardiocyte structure and surface area were assessed, in initially identified cells, both by serial light microscopy and by terminal electron microscopy. Cardiocyte function was assessed in terms of the ability to exclude trypan blue, to remain quiescent with relaxed sarcomeres containing I-bands, and to shorten in response to electrical stimulation. Cardiocyte composition was first assessed by quantitative gel electrophoresis of proteins and then by microfluorimetric measurement of ribonucleic acid, protein, and deoxyribonucleic acid. In addition, cardiocyte incorporation of [3H]thymidine into deoxyribonucleic acid and [3H]uridine into ribonucleic acid were measured. Loading via substrate adhesion was found to be very effective in terms of each of these measurements in retaining the differentiated features of adult cardiocytes for up to 2 weeks in culture; unattached and thus unloaded cardiocytes quickly dedifferentiated. Conditions thought to stimulate cardiac growth, including catecholamine stimulation, were found to be ineffective. These experiments demonstrate that external load has a primary role in the maintenance of the basic differentiated properties of adult mammalian cardiocytes.

Platelet arachidonate metabolism and platelet function in zinc-deficient rats

To determine the effect of zinc status on arachidonate metabolism and the initiation of aggregation by a prostaglandin endoperoxide analog (U-44069), immature rats were fed for 5 days a low zinc (less than 1 ppm) or control (100 ppm Zn) diet based on soybean protein. In vitro production of thromboxane B2 (TXB2) by platelet-rich plasma after stimulation by either arachidonate (0.2 mM) or ADP (0.2 microM) was not changed by dietary zinc deprivation, even though bleeding time was prolonged. Oxygenation of exogenous arachidonate, catalyzed by either the cyclooxygenase or lipoxygenase pathway, was not affected by zinc deficiency. Platelet aggregation in response to the prostaglandin endoperoxide analog at both 8 and 16 microM was impaired by dietary zinc deprivation. While short-term zinc deprivation decreased platelet response to minimal levels of aggregating agents, production of arachidonate metabolites was unimpaired. It is postulated that platelet response to the products of arachidonate metabolism is reduced.