Mass cytometry as a tool in target validation and drug discovery

Mass cytometry provides highly multiparametric data at a single cell level, coupling the specificity and sensitivity of time-of-flight mass spectrometry with the single-cell throughput of flow cytometry. It offers great value in interrogating the potentially heterogenous impact that a drug may have on a biological system, allowing an investigator to capture not just changes in cell behavior, but how these changes may differ between cell subtypes. In this chapter, we review the technical details of the platform as well as its limitations, before describing our approach to planning and running a mass cytometry experiment. A series of method modules, spanning the staining process through to data cleaning, are described that are then combined to create three separate experiments. The first experiment illustrates a core process in mass cytometry: the validation and titration of a metal-conjugated antibody reporter. The second experiment explores the impact of a kinase inhibitor on cell cycle and apoptosis pathways of a human myeloma cell line. And the third experiment exploits the multiparametric capability of mass cytometry, by exploring the differential expression changes in a transcription factor upon drug treatment across the cellular compartments of a peripheral blood mononuclear cell sample.

Digitally Assisted Peer Recovery Coach to Facilitate Linkage to Outpatient Treatment Following Inpatient Alcohol Withdrawal Treatment: Proof-of-Concept Pilot Study

BACKGROUND

Alcohol use disorder (AUD), associated with significant morbidity and mortality, continues to be a major public health problem. The COVID-19 pandemic exacerbated the impact of AUD, with a 25% increase in alcohol-related mortality from 2019 to 2020. Thus, innovative treatments for AUD are urgently needed. While inpatient alcohol withdrawal management (detoxification) is often an entry point for recovery, most do not successfully link to ongoing treatment. Transitions between inpatient and outpatient treatment pose many challenges to successful treatment continuation. Peer recovery coaches-individuals with the lived experience of recovery who obtain training to be coaches-are increasingly used to assist individuals with AUD and may provide a degree of continuity during this transition.

OBJECTIVE

We aimed to evaluate the feasibility of using an existing care coordination app (Lifeguard) to assist peer recovery coaches in supporting patients after discharge and facilitating linkage to care.

METHODS

This study was conducted on an American Society of Addiction Medicine-Level IV inpatient withdrawal management unit within an academic medical center in Boston, MA. After providing informed consent, participants were contacted by the coach through the app, and after discharge, received daily prompts to complete a modified version of the brief addiction monitor (BAM). The BAM inquired about alcohol use, risky, and protective factors. The coach sent daily motivational texts and appointment reminders and checked in if BAM responses were concerning. Postdischarge follow-up continued for 30 days. The following feasibility outcomes were evaluated: (1) proportion of participants engaging with the coach before discharge, (2) proportion of participants and the number of days engaging with the coach after discharge, (3) proportion of participants and the number of days responding to BAM prompts, and (4) proportion of participants successfully linking with addiction treatment by 30-day follow-up.

RESULTS

All 10 participants were men, averaged 50.5 years old, and were mostly White (n=6), non-Hispanic (n=9), and single (n=8). Overall, 8 participants successfully engaged with the coach prior to discharge. Following discharge, 6 participants continued to engage with the coach, doing so on an average of 5.3 days (SD 7.3, range 0-20 days); 5 participants responded to the BAM prompts during the follow-up, doing so on an average of 4.6 days (SD 6.9, range 0-21 days). Half (n=5) successfully linked with ongoing addiction treatment during the follow-up. The participants who engaged with the coach post discharge, compared to those who did not, were significantly more likely to link with treatment (83% vs 0%, χ²=6.67, P=.01).

CONCLUSIONS

The results demonstrated that a digitally assisted peer recovery coach may be feasible in facilitating linkage to care following discharge from inpatient withdrawal management treatment. Further research is warranted to evaluate the potential role for peer recovery coaches in improving postdischarge outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05393544; https://www.clinicaltrials.gov/ct2/show/NCT05393544.

Abstract 1247: Comprehensive molecular profiling to predict first-line immunochemotherapy outcomes in inoperable esophageal adenocarcinoma

For patients with inoperable esophageal adenocarcinoma (EAC), prognosis on conventional chemotherapy (CTX) remains poor. In 2021, the FDA approved two αPD-1 immune checkpoint inhibitors (ICI) for addition to fluoropyrimidine/platinum-containing CTX in this first-line setting. As ICI+CTX enters the clinic, understanding ICI responses and predicting which patients will benefit from ICI addition are key challenges. To address these challenges, we assessed clinical and molecular profiles from the experimental LUD2015-005 trial (NCT02735239, EudraCT 2015-005298-19). Treatment consisted of an initial four-week ICI-only window with durvalumab (αPD-L1) with or without a single dose of tremelimumab (αCTLA-4), followed by 6 cycles of ICI+CTX (CapOx). 38 inoperable patients received treatment (35 EAC; 3 ESCC); median overall survival (OS) and progression-free survival (PFS) were 13.4 and 9.3 months, respectively. All patients reported at least one treatment emergent adverse event (TEAE), with 29 (76.3%) reporting grade 3 or higher TEAEs. EAC patients with available samples (n = 33) were taken forward for biomarker analysis, using tumor and adjacent normal biopsies collected at pre-treatment (PreTx), after four weeks of ICI-only (ICI-4W), and at the end of ICI+CTX (PostTx).

Transcriptomic comparison of paired PreTx and ICI-4W EAC biopsies (n = 28) revealed ICI-induced upregulation of a novel T-cell inflammation signature (termed INCITE). Stronger INCITE upregulation correlated with greater tumor shrinkage during the ICI-only window, and tumors with minimal INCITE upregulation showed markers of ICI resistance, including Innate PD-1 Resistance (IPRES). Despite correlation with ICI-only responses, INCITE changes were not associated with overall ICI+CTX outcomes.

To find predictive biomarkers of ICI+CTX outcomes, we conducted comprehensive genomic and transcriptomic profiling of PreTx EAC biopsies (n = 33). First, we generated a novel 65,000 cell scRNA-seq dataset and designed a deconvolution workflow to resolve tumor cell composition. Unexpectedly, monocyte composition was strongly linked with greater overall survival (OS) (HR: 0.40 [0.23-0.69]; p = 0.001; FDR = 0.047). Coding tumor mutational burden (TMB) was also associated with improved OS (HR: 0.50 [0.28-0.89]; p = 0.019). Multivariate modelling suggested monocyte composition and TMB were independent and complementary predictors of outcomes. Neither factor was associated with outcomes in a TCGA cohort of EAC patients not treated with ICI, suggesting these biomarkers may be specific to ICI or ICI+CTX.

Our findings suggest monocyte composition and TMB may identify EAC patients likely to benefit from ICI+CTX. INCITE upregulation may also serve as a useful monitor of ICI efficacy. These timely findings further our understanding of ICI response and resistance and may help inform patient selection for ICI+CTX.

Citation Format: Thomas M. Carroll, Joseph A. Chadwick, Richard P. Owen, Michael J. White, Joseph Kaplinsky, Iliana Peneva, Anna Frangou, Jaeho Chang, Phil F. Xie, Andrew Roth, Bob Amess, Hantao Lou, Katy J. McCann, Georgina Berridge, Roman Fischer, Chansavath Phetsouphanh, Ayo O. Omiyale, Brittany-Amber Jacobs, David Ahern, Simon R. Lord, Stewart Norris-Bulpitt, Sam T. Dobbie, Lucinda Griffiths, Kristen Aufiero Ramirez, Toni Ricciardi, Mary J. Macri, Aileen Ryan, Ralph R. Venhaus, Benoit J. Van den Eynde, Ioannis Karydis, Benedikt M. Kessler, Benjamin Schuster-Böckler, Mark R. Middleton, Xin Lu. Comprehensive molecular profiling to predict first-line immunochemotherapy outcomes in inoperable esophageal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1247.

Hepcidin-Mediated Hypoferremia Disrupts Immune Responses to Vaccination and Infection

BACKGROUND

How specific nutrients influence adaptive immunity is of broad interest. Iron deficiency is the most common micronutrient deficiency worldwide and imparts a significant burden of global disease; however, its effects on immunity remain unclear.

METHODS

We used a hepcidin mimetic and several genetic models to examine the effect of low iron availability on T cells in vitro and on immune responses to vaccines and viral infection in mice. We examined humoral immunity in human patients with raised hepcidin and low serum iron caused by mutant TMPRSS6. We tested the effect of iron supplementation on vaccination-induced humoral immunity in piglets, a natural model of iron deficiency.

FINDINGS

We show that low serum iron (hypoferremia), caused by increased hepcidin, severely impairs effector and memory responses to immunizations. The intensified metabolism of activated lymphocytes requires the support of enhanced iron acquisition, which is facilitated by IRP1/2 and TFRC. Accordingly, providing extra iron improved the response to vaccination in hypoferremic mice and piglets, while conversely, hypoferremic humans with chronically increased hepcidin have reduced concentrations of antibodies specific for certain pathogens. Imposing hypoferremia blunted the T cell, B cell, and neutralizing antibody responses to influenza virus infection in mice, allowing the virus to persist and exacerbating lung inflammation and morbidity.

CONCLUSIONS

Hypoferremia, a well-conserved physiological innate response to infection, can counteract the development of adaptive immunity. This nutrient trade-off is relevant for understanding and improving immune responses to infections and vaccines in the globally common contexts of iron deficiency and inflammatory disorders.

FUNDING

Medical Research Council, UK.

ROS-producing immature neutrophils in giant cell arteritis are linked to vascular pathologies

Giant cell arteritis (GCA) is a common form of primary systemic vasculitis in adults, with no reliable indicators of prognosis or treatment responses. We used single cell technologies to comprehensively map immune cell populations in the blood of patients with GCA and identified the CD66b⁺CD15⁺CD10^lo/–CD64^– band neutrophils and CD66b^hiCD15⁺CD10^lo/–CD64^+/bright myelocytes/metamyelocytes to be unequivocally associated with both the clinical phenotype and response to treatment. Immature neutrophils were resistant to apoptosis, remained in the vasculature for a prolonged period of time, interacted with platelets, and extravasated into the tissue surrounding the temporal arteries of patients with GCA. We discovered that immature neutrophils generated high levels of extracellular reactive oxygen species, leading to enhanced protein oxidation and permeability of endothelial barrier in an in vitro coculture system. The same populations were also detected in other systemic vasculitides. These findings link functions of immature neutrophils to disease pathogenesis, establishing a clinical cellular signature of GCA and suggesting different therapeutic approaches in systemic vascular inflammation.

Bona fide immature neutrophil subsets produce unchecked extracellular ROS that contributes to vascular pathologies.

Experiencing Cancer in Appalachian Kentucky

Quilted Appalachian Sunset©2011 Jim Harrisjim-harris.pixels.com Nothing tells the story of people working together better than a community quilt. A diversity of talents, colors, and materials brought together through skill and shared purpose. Perhaps never before have we as Americans needed a stronger reminder that many hands make short work of big problems. The work presented here by the L.A.U.N.C.H. Collaborative offers a new framework for health care that could be compared to a digital quilt, powered by community-based participatory design, with lived expertise and the newest advances in broadband-enabled connected health solutions. This work demonstrates the value and need to engage local communities and what can be learned when beneficiaries and traditional caregivers work together to develop healthcare solutions.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Abstract A91: T-cell regulation in pancreatic ductal adenocarcinoma

Background: Pancreatic cancer has the worst prognosis of any human malignancy. We have shown using transcriptomics and histopathology that immune infiltrate in resection samples from a Whipple’s operation is predictive of prognosis. In particular, lymphocytes appear to be a major prognostic marker. With promising immunotherapies being proposed for other cancers, there is a need for a deeper understanding of the immune landscape of pancreatic cancer to identify points of intervention.

Methods: We have developed a 37-marker mass cytometry staining panel to characterize the dominant immune populations within primary pancreatic cancer. Our panel further analyzes T-cell subpopulations and their functional status, including a host of clinically relevant checkpoint markers and immunosuppressive signatures.

Results: The degree of immune infiltration we observe is highly variable between patients, but all patients equivocally show a complex immune microenvironment consistent of macrophages, neutrophils, and different lymphocytes. The T cells infiltrating the tumor, both CD4 and CD8 T cells, appear to be dysfunctional with hardly any activation signature. A highly suppressive phenotype also characterizes the regulatory T-cell population. Our data suggest that the microenvironment of pancreatic cancer is extremely suppressive and could be a major driver of poor prognosis. Yet, this work identifies potential therapeutic targets and avenues that should be further investigated and may inspire future clinical trials.

Future Work: We are planning to investigate the behavior of T-regs from PDAC using in vitro assays. To that end, we will use a recently developed advanced 3D culture system to visualize their interactions with CD8s and the functional consequences of those interactions on CD8-mediated killing.

Citation Format: Shivan Sivakumar, Enas Abu-Shah, David Ahern, Nagina Mangal, Srikanth Reddy, Aniko Rendek, Zahir Soonawalla, Michael Silva, Mark Middleton, Michael L. Dustin. T-cell regulation in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A91.

Barn-Raising on the Digital Frontier: The L.A.U.N.C.H. Collaborative

A meta-analysis of oncology papers from around the world revealed that cancer patients who lived more than 50 miles away from hospital centers routinely presented with more advanced stages of disease at diagnosis, exhibited lower adherence to prescribed treatments, presented with poorer diagnoses, and reported a lower quality of life than patients who lived nearer to care facilities. Connected health approaches-or the use of broadband and telecommunications technologies to evaluate, diagnose, and monitor patients beyond the clinic-are becoming an indispensable tool in medicine to overcome the obstacle of distance.

Abstract B52: The T-cell architecture of pancreatic ductal adenocarcinoma

Pancreatic cancer has the worst prognosis of any human malignancy. Our recent work has shown that immune infiltrate by transcriptomics and histopathology can predict prognosis after a Whipple’s operation, with lymphocyte infiltration being the most important prognostic marker. We have profiled T cells within primary pancreatic cancer to understand the T-cell architecture within the tumor. We have used a 37-marker T cell-focused panel to study the immune infiltrate. We see a diverse immunosuppressive immune microenvironment within the primary tumor. There is a complex architecture of macrophages, neutrophils, and T cells. The commonest CD4 T cells in the microenvironment are Tregs. There are potential novel therapeutic strategies for Tregs using unique checkpoint inhibitors. The CD8 T cells have PD-1 activity but are not activated or proliferating. The poor prognosis of pancreatic cancer could be explained by the immunosuppressive microenvironment, but there are opportunities to drug Tregs in this disease.

Citation Format: Shivan Sivakumar, Enas Abu Shah, David Ahern, Nagina Mangal, Srikanth Reddy, Aniko Rendek, Zahir Soonawalla, Michael Silva, Mark Middleton, Michael Dustin. The T-cell architecture of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr B52.

Minimally invasive approaches to the management of anastomotic leakage following restorative rectal cancer resection

AIM

Management of anastomotic leakage (AL) following rectal resection has evolved with increasing use of less invasive techniques. The aim of this study was to review the management of AL following restorative rectal cancer resection in a tertiary referral centre.

METHOD

A retrospective review of a prospectively maintained database was performed. The primary outcome was successful management of AL. The secondary outcome was the impact of AL on oncological outcome.

RESULTS

Five hundred and two restorative rectal cancer resections were performed during the study period. The incidence of AL was 9.9% (n = 50). AL occurred more commonly following neoadjuvant chemoradiotherapy (n = 31/252, 12.3%) than in those who did not receive neoadjuvant chemoradiotherapy (n = 19/250, 7.6%; P = 0.107); however, this was not statistically significant. Successful minimally invasive drainage was achieved in 28 patients (56%, radiological n = 24, surgical n = 4). Trans-rectal drainage was the most common drainage method (n = 14). The median duration of drainage was longer in the neoadjuvant group (27 vs 18 days). Surgical intervention was required in 11 patients, with anastomotic takedown and end-colostomy formation was most commonly required. Successful management of AL with drainage (maintenance of the anastomosis without the need for further intervention) was achieved in 26 of the 28 patients. There were no significant differences in overall or disease-free survival when patients with AL were compared with patients without AL (69.4% vs 72.6%, P = 0.99 and 78.7% vs 71.3%, P = 0.45, respectively).

CONCLUSION

In selected patients, AL following restorative rectal resection can be effectively controlled using minimally invasive radiological or surgical drainage without the need for further intervention.

Structural Remodeling of the Human Colonic Mesenchyme in Inflammatory Bowel Disease

Intestinal mesenchymal cells play essential roles in epithelial homeostasis, matrix remodeling, immunity, and inflammation. But the extent of heterogeneity within the colonic mesenchyme in these processes remains unknown. Using unbiased single-cell profiling of over 16,500 colonic mesenchymal cells, we reveal four subsets of fibroblasts expressing divergent transcriptional regulators and functional pathways, in addition to pericytes and myofibroblasts. We identified a niche population located in proximity to epithelial crypts expressing SOX6, F3 (CD142), and WNT genes essential for colonic epithelial stem cell function. In colitis, we observed dysregulation of this niche and emergence of an activated mesenchymal population. This subset expressed TNF superfamily member 14 (TNFSF14), fibroblastic reticular cell-associated genes, IL-33, and Lysyl oxidases. Further, it induced factors that impaired epithelial proliferation and maturation and contributed to oxidative stress and disease severity in vivo. Our work defines how the colonic mesenchyme remodels to fuel inflammation and barrier dysfunction in IBD.

•

Single-cell census of the colonic mesenchyme reveals unexpected heterogeneity

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Identification of the colonic crypt niche mesenchymal cell expressing SOX6 and Wnts

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Definition of fundamental aspects of mesenchymal remodeling in colitis

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Analysis of colitis-associated mesenchymal cells reveals pathogenicity drivers

A qualitative analysis to optimize a telemonitoring intervention for heart failure patients from disparity communities

Background

The use of telemonitoring is a promising approach to optimizing outcomes in the treatment of heart failure (HF) for patients living in the community. HF telemonitoring interventions, however, have not been tested for use with individuals residing in disparity communities.

Methods

The current study describes the results of a community based participatory research approach to adapting a telemonitoring HF intervention so that it is acceptable and feasible for use with a lower-income, Black and Hispanic patient population. The study uses the ADAPT-ITT framework to engage key community stakeholders in the process of adapting the intervention in the context of two consecutive focus groups. In addition, data from a third focus group involving HF telemonitoring patient participants was also conducted. All three focus group discussions were audio recorded and professionally transcribed and lasted approximately two hours each. Structural coding was used to mark responses to topical questions in the interview guide.

Results

This is the first study to describe the formative process of a community-based participatory research study aimed at optimizing telehealth utilization among African-American and Latino patients from disparity communities. Two major themes emerged from qualitative analyses of the focus group data. The first theme that arose involved suggested changes to the equipment that would maximize usability. Subthemes identified included issues that reflect the patient populations targeted, such as Spanish translation, font size and medical jargon. The second theme that arose involved suggested changes to the RCT study structure in order to maximize participant engagement. Subthemes also identified issues that reflect concerns of the targeted patient populations, such as the provision of reassurances regarding identity protection to undocumented patients in implementing an intervention that utilizes a camera, and that their involvement in telehealth monitoring would not replace their clinic care, which for many disparity patients is their only connection to medical care.

Conclusions

The adaptation, based on the analysis of the data from the three focus groups, resulted in an intervention that is acceptable and feasible for HF patients residing in disparity communities.

Trial registration

NCT02196922; ClinicalTrials.gov (US National Institutes of Health).

Electronic supplementary material

The online version of this article (doi:10.1186/s12911-016-0300-9) contains supplementary material, which is available to authorized users.

Cognitive predictors of skilled performance with an advanced upper limb multifunction prosthesis: a preliminary analysis

Purpose The objectives were to 1) identify major cognitive domains involved in learning to use the DEKA Arm; 2) specify cognitive domain-specific skills associated with basic versus advanced users; and 3) examine whether baseline memory and executive function predicted learning. Method Sample included 35 persons with upper limb amputation. Subjects were administered a brief neuropsychological test battery prior to start of DEKA Arm training, as well as physical performance measures at the onset of, and following training. Multiple regression models controlling for age and including neuropsychological tests were developed to predict physical performance scores. Prosthetic performance scores were divided into quartiles and independent samples t-tests compared neuropsychological test scores of advanced scorers and basic scorers. Baseline neuropsychological test scores were used to predict change in scores on physical performance measures across time. Results Cognitive domains of attention and processing speed were statistically significantly related to proficiency of DEKA Arm use and predicted level of proficiency. Conclusions Results support use of neuropsychological tests to predict learning and use of a multifunctional prosthesis. Assessment of cognitive status at the outset of training may help set expectations for the duration and outcomes of treatment. Implications for Rehabilitation Cognitive domains of attention and processing speed were significantly related to level of proficiencyof an advanced multifunctional prosthesis (the DEKA Arm) after training. Results provide initial support for the use of neuropsychological tests to predict advanced learningand use of a multifunctional prosthesis in upper-limb amputees. Results suggest that assessment of patients' cognitive status at the outset of upper limb prosthetictraining may, in the future, help patients, their families and therapists set expectations for theduration and intensity of training and may help set reasonable proficiency goals.

Balance between activating NKG2D, DNAM-1, NKp44 and NKp46 and inhibitory CD94/NKG2A receptors determine natural killer degranulation towards rheumatoid arthritis synovial fibroblasts

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and synovial hyperplasia leading to progressive joint destruction. Fibroblast-like synoviocytes (FLS) are central components of the aggressive, tumour-like synovial structure termed pannus, which invades the joint space and cartilage. A distinct natural killer (NK) cell subset expressing the inhibitory CD94/NKG2A receptor is present in RA synovial fluid. Little is known about possible cellular interactions between RA-FLS and NK cells. We used cultured RA-FLS and the human NK cell line Nishi, of which the latter expresses an NK receptor repertoire similar to that of NK cells in RA synovial fluid, as an in vitro model system of RA-FLS/NK cell cross-talk. We show that RA-FLS express numerous ligands for both activating and inhibitory NK cell receptors, and stimulate degranulation of Nishi cells. We found that NKG2D, DNAM-1, NKp46 and NKp44 are the key activating receptors involved in Nishi cell degranulation towards RA-FLS. Moreover, blockade of the interaction between CD94/NKG2A and its ligand HLA-E expressed on RA-FLS further enhanced Nishi cell degranulation in co-culture with RA-FLS. Using cultured RA-FLS and the human NK cell line Nishi as an in vitro model system of RA-FLS/NK cell cross-talk, our results suggest that cell-mediated cytotoxicity of RA-FLS may be one mechanism by which NK cells influence local joint inflammation in RA.

Epilepsy health consumer groups and charities; how representative of patients are they? The results of a pilot study

PURPOSE

In the United Kingdom all health care providers are encouraged to consult with user groups. The submissions of charities and patient advocacy groups to NICE and SIGN are considered reflective of the patient groups they purport to represent, yet little is known about how representative they are. This pilot study was designed to ascertain how many patients attending a hospital based epilepsy clinic were members of such advocacy groups.

METHODS

Patients were asked to complete a brief 9-question questionnaire before they left the clinic.

RESULTS

One hundred and twenty-five questionnaires were distributed, of which 101 were returned. Seventeen percent of patients were members of advocacy groups, with several being members of more than one charity/group. Only seven percent of the respondents had ever been contacted by an advocacy group to canvass their opinions. Seventy percent of patients questioned stated they thought a frank discussion with their physician, or specialist nurse was more likely to influence patient services. Patients with long duration of disease and taking multiple anti-epileptic drugs were more likely to be members of charity/advocacy groups.

CONCLUSIONS

As patient charities in the U.K. are often in receipt of public funds, and actively seek to influence public policy this raises the question of whether they should be required to consult more widely with the people they claim to represent.

Chemokine responsiveness of CD4+ CD25+ regulatory and CD4+ CD25- T cells from atopic and nonatopic donors

BACKGROUND

Allergic inflammation is associated with Th2-type T cells, which can be suppressed by CD4+ CD25+ regulatory T cells (Tregs). Both express chemokine receptors (CCR) 4 and CCR8, but the dynamics of expression and effect of atopic status are unknown.

OBJECTIVE

To examine the expression of chemokine receptors by CD4+ CD25+ and CD4+ CD25- T cells from atopic and nonatopic donors, and document response to allergen stimulation in vitro.

METHODS

Chemokine receptor expression was examined by flow cytometry and quantitative PCR of CD4+ CD25hi and CD4+ CD25- T cells from atopics and nonatopics. Responsiveness to chemokines was by actin polymerization. Dynamics of chemokine receptor expression in 6-day allergen-stimulated cultures was analysed by carboxyfluoroscein succinimidyl ester labelling.

RESULTS

CD4+ CD25hi Tregs preferentially expressed CCR3, CCR4, CCR5, CCR6 and CCR8. CD4+ CD25hi Tregs responded to the chemokine ligands for CCR4, CCR6 and CCR8 (CCL17, 22, 20 and 1 respectively), with no differences between atopic and nonatopic donors. Over 6-day allergen stimulation, CD4+ CD25+ T-cells downregulated CCR4 and upregulated CCR7, in contrast to CD4+ CD25- effector cells, which downregulated CCR7 and upregulated CCR4.

CONCLUSIONS

CCR4, CCR6 and CCR8 have potential roles in localization of both CD4+ CD25+ regulatory and CD4+ CD25- effector T cells to sites of allergic inflammation. Upregulation of CCR7 and downregulation of CCR4 upon allergen stimulation of Tregs may allow their recirculation from sites of inflammation, in contrast to retention of effector T cells.

Interactive voice response system (IVRS) in health care services

Recent advances in telecommunications technology have created opportunities to enhance the quality of health care services through telehealth, the use of telecommunications and information technologies to deliver health care. However, the diverse technologies and applications encompassed by telehealth have tended to confuse discussions of the effectiveness of these programs. An interactive voice response system (IVRS) is a simple, yet effective telehealth application that improves access to health care by continuing care beyond the hospital setting, with specially tailored programs that are easily accessible to patients around the clock. Often described as a telephone connected to a "talking computer," an IVRS allows patient interaction for data collection or to deliver recorded telephone messages related to medication compliance or behavior modification. Despite easy access to touchtone telephone services and growing familiarity with IVRS, many health care providers are unaware of these programs. This paper reviews the infrastructure of IVRS technology and its uses in health care.

Encapsulation in biodegradable microparticles enhances serum antibody response to parenterally-delivered beta-amyloid in mice

Poly(lactide-co-glycolide) (PLG) microspheres were tested as a parenteral delivery system for human beta-amyloid (1-42) (Abeta), a potential immunotherapeutic undergoing assessment in Phase 1 studies for Alzheimer's disease (AD). Abeta was successfully encapsulated in PLG microspheres of average sizes of 3 or 15 microm diameter. Swiss Webster (SW) mice were injected by the sub-cutaneous (s.c.) or intra-peritoneal (i.p.) routes with 3-33 microg Abeta. Abeta-PLG microparticles (3 microm) induced dose-dependent antibody responses, which were maximal at 33 microg Abeta, while Abeta in phosphate-buffered saline (PBS) produced weak antibody responses at the same doses by both routes. Significantly increased antibody responses were seen for both small and large particle formulations given by the i.p. route in comparison to the s.c route. It was previously reported that passive immunisation with Abeta-specific antibodies cleared amyloid plaques in a mouse model of AD (Bard F, Cannon C, Barbour R, et al. Peripherally administered antibodies against amyloid beta-peptide enter the nervous system and reduce pathology in a mouse model of Alzheimer disease. Nature Med 2000;6:916-19), an indication that induction of serum antibody is a prerequisite for efficacy.

From primary care physician employment to private practice: easing the transition

In most cases, the practice acquisition and employment strategy of the 1990s has backfired, with acquired physician practices losing in the range of $50,000 to $100,000 or more per physician annually. There are two alternatives for addressing the operating deficits incurred from practice ownership and physician employment: (1) restructuring through the implementation of network-wide and practice-specific initiatives to improve financial performance; or (2) wholesale (i.e., all practices) or selective practice divestiture, depending on the individual practice financial performance and "fit" with the physician network strategic priorities. Unraveling a decade's worth of physician-health system relationships that are grounded by the notion of acquisition and employment is going to be a complex process for both parties. But given the magnitude of financial losses on acquired practices and the inability of health care providers to sustain future losses, there simply are not options beyond restructuring or divesting these relationships.

Venlafaxine: in vitro inhibition of CYP2D6 dependent imipramine and desipramine metabolism; comparative studies with selected SSRIs, and effects on human hepatic CYP3A4, CYP2C9 and CYP1A2

AIMS

In order to anticipate drug-interactions of potential clinical significance the ability of the novel antidepressant, venlafaxine, to inhibit CYP2D6 dependent imipramine and desipramine 2-hydroxylation was investigated in human liver microsomes. The data obtained were compared with the selective serotonin re-uptake inhibitors, fluoxetine, sertraline, fluvoxamine and paroxetine. Venlafaxine's potential to inhibit several other major P450 s was also studied (CYP3A4, CYP2D6, CYP1A2).

METHODS

Ki values for venlafaxine, paroxetine, fluoxetine, fluvoxamine and sertraline as inhibitors of imipramine and desipramine 2-hydroxylation were determined from Dixon plots of control and inhibited rate data in human hepatic microsomal incubations. The inhibitory effect of imipramine and desipramine on liver microsomal CYP2D6 dependent venlafaxine O-demethylation was determined similarly. Venlafaxine's IC50 values for CYP3A4, CYP1A2 CYP2C9 were determined based on inhibition of probe substrate activities (testosterone 6 beta-hydroxylation, ethoxyresorufin O-dealkylase and tolbutamide 4-hydroxylation, respectively).

RESULTS

Fluoxetine, paroxetine, and fluvoxamine were potent inhibitors of imipramine 2-hydroxylase activity (Ki values of 1.6 +/- 0.8, 3.2 +/- 0.8 and 8.0 +/- 4.3 microM, respectively; mean +/- s.d., n = 3), while sertraline was less inhibitory (Ki of 24.7 +/- 8.9 microM). Fluoxetine also markedly inhibited desipramine 2-hydroxylation with a Ki of 1.3 +/- 0.5 microM. Venlafaxine was less potent an inhibitor of imipramine 2-hydroxylation (Ki of 41.0 +/- 9.5 microM) than the SSRIs that were studied. Imipramine and desipramine gave marked inhibition of CYP2D6 dependent venlafaxine O-demethylase activity (Ki values of 3.9 +/- 1.7 and 1.7 +/- 0.9 microM, respectively). Venlafaxine did not inhibit ethoxyresorufin O-dealkylase (CYP1A2), tolbutamide 4-hydroxylase (CYP2C9) or testosterone 6 beta-hydroxylase (CYP3A4) activities at concentrations of up to 1 mM.

CONCLUSIONS

It is concluded that venlafaxine has a low potential to inhibit the metabolism of substrates for CYP2D6 such as imipramine and desipramine compared with several of the most widely used SSRIs, as well as the metabolism of substrates for several of the other major human hepatic P450s.

Bacterial superantigens induce the proliferation of resting gamma/delta receptor bearing T cells

We observe that highly purified (> or = 97% pure) gamma/delta T cells isolated from normal peripheral blood proliferate to bacterial toxin supperantigens SEA, SEB, SED, and TSST-1. MHC class II molecules were necessary and sufficient for the recognition of superantigens by gamma/delta T cells because MHC Class II deficient B cell line failed to support the proliferation of gamma/delta T cells to toxins and murine L cells transfected with HLA-DR but not untransfected cells were capable of presenting toxins to gamma/delta T cells. As in the case with alpha/beta T cells, bacterial superantigens synergized with PMA in causing the proliferation of purified gamma/delta T cells rigorously depleted of accessory cells. Together, our findings suggest that gamma/delta T cells recognize and respond to bacterial superantigens in a manner similar to alpha/beta T cells.

CD40 ligand expression is developmentally regulated in human thymocytes

Thymic selection involves the interaction between developing thymocytes and the thymic microenvironment. CD40 is expressed on thymic epithelial cells and on bone marrow-derived antigen-presenting cells in the thymus. We have investigated the capacity of human thymocytes to express CD40 ligand. CD40 ligand was not detectable on resting immature double-positive (CD4+/CD8+) or resting mature single-positive (CD4+/CD8- or CD4-/CD8+) thymocytes. Immature thymocytes failed to express CD40 ligand on their surface after stimulation with PMA and ionomycin, whereas stimulated CD4+/CD8- mature thymocytes expressed CD40 ligand. Northern blot analysis revealed that CD40 ligand mRNA was detectable in activated mature single-positive thymocytes. CD40 ligand expression by mature thymocytes was associated with the capacity to drive immunoglobulin isotype switching in purified B cells. These results demonstrate that the ability to express CD40 ligand is acquired late in thymocyte development and that mature thymocytes are capable of providing B cells with the activation signals necessary for immunoglobulin isotype switching.

Expression of the CD40 ligand in T lymphocytes and induction of IgE isotype switching

CD40 ligand (CD40L) delivers a contact-dependent signal to B cells which, in the presence of interleukin (IL)-4, drives immunoglobulin isotype switching to IgE. CD40L expression in T cells is transient, requires activation of protein kinase C and a rise in intracellular calcium concentration ([Ca2+]i), and is inhibited by cyclosporin A (CsA). CsA also inhibited T-cell-dependent IL-4-driven IgE synthesis. We have found that expression of CD40L is developmentally regulated. Expression of CD40L was restricted to mature single-positive thymocytes which, in the presence of IL-4, were capable of inducing B cells to undergo IgE isotype switching. CD40L expression was severely decreased in cord blood lymphocytes and was associated with a severely decreased ability to undergo T-cell-dependent IgE isotype switching.

A toxic shock syndrome toxin-1 peptide that shows homology to amino acids 180-193 of mycobacterial heat shock protein 65 is presented as conventional antigen

Peripheral blood mononuclear cells (PBMC) from the majority of adults (12 out of 18 subjects tested) showed an in vitro proliferative response to a 20 amino acid long peptide (peptide 1, a.a 18-37) derived from TSST-1. In contrast, thymocytes and PBMC from cord blood did not proliferate to this peptide. TSST-1 peptide 1 did not induce IL-1 beta mRNA in monocytes indicating that it does not behave as a superantigen. Proliferation of PBMC to peptide 1 could be blocked by anti-HLA-DR, but not by anti-HLA DP or DQ monoclonal antibodies suggesting that HLA-DR molecules are the restriction elements for the recognition of this peptide by T cells. Studies with subjects of known HLA-DR types showed that all types tested are capable of responding to this peptide. Peptide 1 shows homology to a.a 180-193 of mycobacterial hsp 65 and was shown to stimulate the proliferation of T cell lines and T cell clone specific for the purified protein derivative (PPD) of Mycobacterium tuberculosis. This cross reactivity may confer on TSST-1 the potential to trigger self reactivity and may also contribute to the natural immunity against TSST-1.

Decreased expression of the ligand for CD40 in newborn lymphocytes

Immune responses in newborn lymphocytes show a defect in isotype switching from IgM to IgG and IgA. Immunoglobulin isotype switching in B lymphocytes requires a contact-dependent signal from T lymphocytes which is delivered by the ligand for the B cell surface antigen CD40. We investigated the capacity of newborn lymphocytes to express the CD40 ligand and to undergo CD40 ligand-dependent immunoglobulin isotype switching. After stimulation by phorbol ester and ionomycin, newborn lymphocytes expressed markedly decreased amounts of CD40 ligand on their surface compared to normal adult lymphocytes. Northern blot analysis of mRNA derived from activated cord blood lymphocytes also revealed markedly decreased amounts of CD40 ligand mRNA. Decreased expression of CD40 ligand in newborn lymphocytes was associated with a severely decreased ability to undergo T cell-dependent immunoglobulin isotype switching. Newborn lymphocytes synthesized little or no detectable IgE in response to T cell-dependent stimulation by interleukin-4 but synthesized IgE in response to T cell-independent stimulation by CD40 monoclonal antibody and interleukin-4. These results indicate that decreased expression of CD40 ligand in newborn lymphocytes may be the underlying cause of deficient immunoglobulin isotype switching in newborns.

Tritium isotope effect in high-performance liquid chromatography of eicosanoids

A significant difference in retention time between unlabeled and the corresponding multi-tritium-labeled eicosanoid has been observed in the high performance liquid chromatography (HPLC) analysis of 11 eicosanoids. Variations in retention time range from 3-7%, depending on the separation conditions as well as the number and position of the tritium substitution. Multi-tritium-labeled eicosanoids were eluted earlier than the corresponding unlabeled eicosanoid in reversed phase HPLC, whereas no isotope effect was seen with 14C- and 3H2-eicosanoids. Considerations must be given to this tritium isotope effect whenever both multi-tritium-labeled and unlabeled eicosanoids are used for HPLC cochromatography or recovery studies.

Identification and characterization of a lysophosphatidic acid receptor

A specific binding site for 1-[3H]stearoyl-lysophosphatidic acid (stearoyl-LPA) was identified and characterized in membranes prepared from rat brain and Swiss 3T3 fibroblasts. Specific binding of [3H]LPA to these sites was protein dependent, was saturable, reached equilibrium in 15 min, and was displacable by the addition of excess unlabeled LPA. Scatchard analysis of saturation binding experiments indicated that these sites had affinities of 2.0 +/- 0.5 nM and 5.4 +/- 2.6 nM and densities of 19 +/- 3 fmol/micrograms of protein and 38 +/- 6 fmol/micrograms of protein in rat brain and 3T3 cell membranes, respectively. Various LPAs, with different acyl groups in the sn-1-position, competed with [3H]LPA for these binding sites, with a rank order of potency of 1-oleoyl-LPA > 1-stearoyl-LPA = 1-palmitoyl-LPA > 1-myristoyl-LPA. Phosphatidic acid also bound to these sites, but with lower affinity than any LPA tested. Neither lysophosphatidylcholine, lysophosphatidylethanolamine, nor any free fatty acid competed with [3H]LPA for these binding sites. Binding of [3H]LPA to these sites was regulated by nonhydrolyzable guanine nucleotides in both rat brain and 3T3 cell membranes. Furthermore, in 3T3 cells, these sites were regulated by cell density. It was subsequently determined that LPA induced a transient increase in intracellular Ca2+ levels in 3T3 cells. The concentrations required for this response, as well as the rank order of potency of the various LPAs and phosphatidic acid, correlated with the affinity of these compounds for the [3H]LPA binding site. These results suggest that the specific, high affinity, binding sites for [3H]LPA are G protein-coupled receptors.

Cyclosporin A inhibits CD40 ligand expression in T lymphocytes

The ligand for CD40 is expressed on activated T lymphocytes and delivers contact-dependent activation signals to B lymphocytes. The mechanisms regulating CD40 ligand gene expression are largely unknown. Optimal expression of CD40 ligand required activation of protein kinase C and a rise in intracellular calcium concentration. CD40 ligand expression was inhibited by pretreatment of T cells with cyclosporin A. Cyclosporin A analogues inhibited CD40 ligand expression with a potency mirroring the ability of each compound to inhibit calcineurin activity, indicating that calcineurin plays a key role in CD40 ligand gene expression. Cyclosporin A inhibited IL-4-driven CD40 ligand-dependent IgE isotype switching in PBMC but did not inhibit IgE synthesis induced by CD40 mAb plus IL-4. PBMC derived from transplant patients receiving cyclosporin A failed to express CD40 ligand upon stimulation. These results suggest that patients receiving cyclosporin A may be deficient in CD40 ligand-dependent T cell help.

14(R),15(S)-epoxyeicosatrienoic acid (14(R),15(S)-EET) receptor in guinea pig mononuclear cell membranes

A high affinity binding site for 14(R),15(S)-EET, one of the major cytochrome P-450 metabolites of arachidonic acid (AA) in blood vessels, liver, kidney and urine of patients with pregnancy-induced hypertension, has been identified in a membrane preparation from guinea pig mononuclear (GPM) cells. Using a radioligand assay, binding of 14(R),15(S)-[3H]EET to its receptor site was saturable, specific and reversible. Scatchard analysis of saturation binding studies yielded a dissociation constant (Kd) of 5.7 x 10(-9) M, and maximum number of binding sites (Bmax) of 2.4 pmol/mg membrane protein. The specificity of the binding site was determined by competition studies. 14(S),15(R)-EET and 8,9-EET had a Ki of 6.3 and 8.8 nM, respectively, followed by 12(R)-HETE and LTD4. 12(S)-HETE and 5,6-EET were even less effective as a competitive inhibitor of radioligand and binding with Ki values from 2 to 20 microM. Receptor antagonists for TxA2, LTB4, LTD4 and PAF failed to displace 14(R),15(S)-[3H]EET from its binding site on GPM cell membranes. The results correlate well with the reported biological functions of 14,15-EET. In view of its potent biological activities, 14,15-EET may exert its cellular function through the binding and activation of its stereo-specific cell surface binding sites or receptor.

Protein tyrosine phosphorylation induced via the IgG receptors Fc gamma Ri and Fc gamma RII in the human monocytic cell line THP-1

We have investigated the role of protein tyrosine phosphorylation in transmembrane signaling via the IgG receptors Fc gamma RI and Fc gamma RII in the human monocytic cell line THP-1. Fc gamma RI and Fc gamma RII were selectively engaged using the anti-Fc gamma RI mAb 197 (IgG2a) and the anti-Fc gamma RII mAb IV.3 (IgG2b). Addition to cells of mAb 197, but not addition of IgG2a mAb of irrelevant specificity, resulted in the rapid induction of cytoplasmic protein tyrosine phosphorylation as assessed by antiphosphotyrosine immunoblotting. A similar pattern of tyrosine phosphorylation was induced by mAb IV.3, but not by control IgG2b mAb. The induction of tyrosine phosphorylation by anti-Fc gamma R mAb was not dependent on antibody Fc region-FcR interactions, because tyrosine phosphorylation was also induced by cross-linked anti-Fc gamma RI F(ab')2 fragments and by cross-linked anti-Fc gamma RII Fab fragments. To investigate the relationship of Fc gamma R-induced tyrosine phosphorylation and activation of phospholipase C, which is known to follow Fc gamma R engagement, we assessed the effect of the tyrosine kinase inhibitor herbimycin A on Fc gamma R-induced Ca2+ flux. Herbimycin A strongly inhibited cellular Ca2+ flux induced by mAb 197, but did not inhibit Ca2+ flux induced by aluminum fluoride, suggesting that tyrosine phosphorylation may be important in regulating Fc gamma R-mediated activation of phospholipase C. Consistent with this, mAb 197 induced rapid phosphorylation of the gamma-1 isoform of phospholipase C. Finally, herbimycin A strongly inhibited the induction of TNF-alpha mRNA accumulation by Fc gamma R cross-linking. These results suggest that protein tyrosine phosphorylation may play an important role in the activation of phospholipase C and in the induction of monokine gene expression that follows engagement of Fc gamma R in human monocytes.

Protein tyrosine phosphorylation induced via the IgG receptors Fc gamma Ri and Fc gamma RII in the human monocytic cell line THP-1

We have investigated the role of protein tyrosine phosphorylation in transmembrane signaling via the IgG receptors Fc gamma RI and Fc gamma RII in the human monocytic cell line THP-1. Fc gamma RI and Fc gamma RII were selectively engaged using the anti-Fc gamma RI mAb 197 (IgG2a) and the anti-Fc gamma RII mAb IV.3 (IgG2b). Addition to cells of mAb 197, but not addition of IgG2a mAb of irrelevant specificity, resulted in the rapid induction of cytoplasmic protein tyrosine phosphorylation as assessed by antiphosphotyrosine immunoblotting. A similar pattern of tyrosine phosphorylation was induced by mAb IV.3, but not by control IgG2b mAb. The induction of tyrosine phosphorylation by anti-Fc gamma R mAb was not dependent on antibody Fc region-FcR interactions, because tyrosine phosphorylation was also induced by cross-linked anti-Fc gamma RI F(ab')2 fragments and by cross-linked anti-Fc gamma RII Fab fragments. To investigate the relationship of Fc gamma R-induced tyrosine phosphorylation and activation of phospholipase C, which is known to follow Fc gamma R engagement, we assessed the effect of the tyrosine kinase inhibitor herbimycin A on Fc gamma R-induced Ca2+ flux. Herbimycin A strongly inhibited cellular Ca2+ flux induced by mAb 197, but did not inhibit Ca2+ flux induced by aluminum fluoride, suggesting that tyrosine phosphorylation may be important in regulating Fc gamma R-mediated activation of phospholipase C. Consistent with this, mAb 197 induced rapid phosphorylation of the gamma-1 isoform of phospholipase C. Finally, herbimycin A strongly inhibited the induction of TNF-alpha mRNA accumulation by Fc gamma R cross-linking. These results suggest that protein tyrosine phosphorylation may play an important role in the activation of phospholipase C and in the induction of monokine gene expression that follows engagement of Fc gamma R in human monocytes.

Developmental regulation of transmembrane signaling via the T cell antigen receptor/CD3 complex in human T lymphocytes

We have examined transmembrane signaling events via the TCR/CD3 complex (TCR/CD3) at various stages of T cell development for evidence of developmental regulation. Engagement of TCR/CD3 induced defective activation of phospholipase C (PLC) in thymocytes relative to peripheral blood T lymphocytes. The defect in PLC activation via TCR/CD3 was restricted to immature thymocytes (CD3low, CD4+CD8+). Mature thymocytes (CD3high, CD4+CD8-/CD8+CD4-) were similar to PBL in signaling via TCR/CD3. Both immature and mature thymocytes expressed a similar profile of PLC isoenzyme mRNA species, indicating that the defect in signaling in immature thymocytes was not due to altered expression of PLC isoenzymes. Activation of tyrosine phosphorylation pathways implicated in the coupling of TCR/CD3 to PLC was impaired in immature thymocytes, as evidenced by depressed phosphorylation of CD3 zeta subunit after stimulation with anti TCR/CD3 mAb. This was associated with lower levels of p59fyn tyrosine kinase and minimal or undetectable stimulus-induced kinase activation in immature thymocytes relative to mature thymocytes. We conclude that the capacity to signal via TCR/CD3 is regulated during T cell development by mechanisms acting at the level of TCR/CD3-associated tyrosine phosphorylation pathways.

Developmental regulation of transmembrane signaling via the T cell antigen receptor/CD3 complex in human T lymphocytes

We have examined transmembrane signaling events via the TCR/CD3 complex (TCR/CD3) at various stages of T cell development for evidence of developmental regulation. Engagement of TCR/CD3 induced defective activation of phospholipase C (PLC) in thymocytes relative to peripheral blood T lymphocytes. The defect in PLC activation via TCR/CD3 was restricted to immature thymocytes (CD3low, CD4+CD8+). Mature thymocytes (CD3high, CD4+CD8-/CD8+CD4-) were similar to PBL in signaling via TCR/CD3. Both immature and mature thymocytes expressed a similar profile of PLC isoenzyme mRNA species, indicating that the defect in signaling in immature thymocytes was not due to altered expression of PLC isoenzymes. Activation of tyrosine phosphorylation pathways implicated in the coupling of TCR/CD3 to PLC was impaired in immature thymocytes, as evidenced by depressed phosphorylation of CD3 zeta subunit after stimulation with anti TCR/CD3 mAb. This was associated with lower levels of p59fyn tyrosine kinase and minimal or undetectable stimulus-induced kinase activation in immature thymocytes relative to mature thymocytes. We conclude that the capacity to signal via TCR/CD3 is regulated during T cell development by mechanisms acting at the level of TCR/CD3-associated tyrosine phosphorylation pathways.

Prognostic importance of atrial natriuretic peptide in patients with chronic heart failure

Several circulating neurohormones have been shown to have prognostic significance in patients with chronic heart failure, but the relation between plasma levels of atrial natriuretic peptide and mortality in this disorder remains unknown. Plasma levels of immunoreactive atrial natriuretic peptide were measured in 102 patients in whom left ventricular ejection fraction, ventricular arrhythmias on ambulatory electrocardiographic recording and plasma levels of norepinephrine, renin activity, aldosterone and arginine vasopressin were also measured. Compared with patients with atrial natriuretic peptide concentrations below the median value of 125 pg/ml, patients with higher levels of the peptide had a higher plasma renin activity (8.9 +/- 1.8 versus 2.6 +/- 0.4 ng/ml per h) and plasma norepinephrine (858 +/- 116 versus 538 +/- 45 pg/ml), more frequent premature ventricular depolarizations (4,485 +/- 715 versus 2,004 +/- 495/day) and more advanced hemodynamic abnormalities (all p less than 0.05). During the subsequent 13 to 25 months of follow-up, patients with high levels of atrial natriuretic peptide had a significantly lower rate of survival than did those whose initial circulating peptide concentrations were normal or mildly increased (p = 0.01). These data indicate that, in patients with chronic heart failure, plasma atrial natriuretic peptide provides important prognostic information. This may relate to the ability of the hormone to reflect the interplay of several pathophysiologic factors that contribute to mortality in this disease.