Clinical presentation of hemophagocytic lymphohistiocytosis in adults is less typical than in children

OBJECTIVE: Hemophagocytic lymphohistiocytosis in adults is largely underdiagnosed. To improve the rate and accuracy of diagnosis in adults, the clinical and laboratory characteristics of hemophagocytic lymphohistiocytosis were analyzed in and compared between adults and children in a Chinese cohort. METHOD: Data from 50 hemophagocytic lymphohistiocytosis patients, including 34 adults and 16 children who fulfilled the 2004 hemophagocytic lymphohistiocytosis diagnostic criteria, were collected and analyzed. RESULTS: 1. Etiological factors: The proportion of Epstein-Barr virus infection was lower in adults compared with children, whereas fungal infection and natural killer/T cell lymphoma were more frequent in adults (

Platelet and leukocyte activation and their interaction : in experimental prothrombotic and inflammatory states

Atherosclerotic disease is associated with inflammation and thrombosis, both of which involve multi-cellular activation and interaction. The present work has investigated the mechanisms of plateletleukocyte cross-talk in vitro, and explored the possibility of multi-cellular activation in vivo in prothrombotic and inflammatory models in healthy volunteers. Whole blood flow cytometric methods for measuring platelet-leukocyte aggregates (PLAs) were developed and evaluated. The methods involved minimal sample manipulation, avoiding centrifugation or red cell lysis, and no or only mild post-incubation fixation, to minimize in vitro artefacts. Antibodies that block ligand-receptor interactions had little effect in unstimulated samples but totally inhibited agonist-induced PLA formation, indicating that the assays reflect circulating PLAs closely. Gating on leukocyte fluorescence improved assay efficiency. Data from these studies show that all leukocyte subtypes can form heterotypic conjugates, and that activation of either platelets or leukocytes can enhance PLA formation. Granulocytes and monocytes predominate among PLAs. Multi-ligand-receptor systems are involved in PLA formation, but P-selectin bridging to PSGL-1/CD15s is the principal bridging mechanism under most conditions. Activation of leukocytes with fMLP evoked platelet activation. The effect did not depend on PLA formation, and was markedly inhibited by PAF antagonism or 5-lipoxygenase inhibition. Collagenactivated platelets evoked leukocyte activation. The effect was not inhibited by a thromboxane A2 receptor antagonist, which abolished collagen-induced platelet P-selectin expression, but was inhibited by blocking PLA formation, indicating that the effect depended on cell-cell contact. Interestingly, GPIIb/IIIa blockade by an nonpeptide inhibitor, SR121566, inhibited platelet-leukocyte cross-talk, and a cocktail containing antibodies to P-selectin, GPIIb/IIIa, and CD 1 1b/CD 18 abolished fMLP-induced leukocyte activation. Thus, platelet-leukocyte cross-talk involved multiple mediators and mechanisms, and adhesion molecules seem to be important in cellular signaling during platelet and leukocyte activation. Strenuous exercise provoked a prothrombotic state, and endotoxin injection induced systemic inflammation in humans. Both interventions resulted in multicellular activation in vivo and enhanced thrombin generation. Platelet activation was shown by increased circulating P-selectin positive platelets and platelet-platelet aggregates, elevated plasma soluble P-selectin levels, and enhanced platelet responsiveness to in vitro stimulation. Leukocyte activation was shown, with increased CD11b expression in circulating leukocytes, elevated plasma elastase levels, as well as enhanced leukocyte reactivity to in vitro stimulation. This resulted in enhanced platelet-leukocyte interaction, as evidenced by increased circulating PLAs and enhanced agonist-induced PLA formation in vitro. Endothelial activation and thrombin generation were shown by markedly increased plasma vWF and F1+2 levels, respectively. Aspirin ingestion at a daily dose of 500 mg reduced platelet P-selectin expression at rest slightly, and inhibited neutrophil responsiveness to fMLP stimulation, but did not counteract the prothrombotic effects of exercise. Adenosine infusion at a dose of 40 [my]g/Kg/min induced leukocytosis in the absence of endotoxemia, probably due to inhibition of leukocyte adhesion and migration on/into the vessel wall. Adenosine infusion attenuated endotoxemia-induced platelet and leukocyte activation moderately, as shown by modest inhibition on platelet reactivity and more marked inhibition of leukocyte adhesion and migration. The latter also resulted in the retention of more activated leukocytes and PLAs in the circulation, and might thus limit leukocyte-mediated tissue damage. Taken together, the present studies suggest that thrombosis and inflammation are closely related pathophysiological processes that involve multicellular activation of platelets, leukocytes, and endothelial cells and enhanced intercellular cross-talk. Aspirin does not counteract prothrombotic effects of exercise. Adenosine is a potentially useful antiinflammatory agent, but the treatment strategy needs to be optimized to achieve clinically relevant effects

Statistical diagnostics for longitudinal data analysis : forward search of the GEE method

In longitudinal data analysis, masking and swamping (MS) are two common effects that can cause severe problems. Successful identification of MS effects is essential to both outlier detection and longitudinal data analysis because ignorance of the MS effects can make the conclusion of analysis totally meaningless and misleading. In this thesis, a statistical method for analyzing and diagnosing longitudinal data sets is proposed as the forward search of the generalized estimating equation (GEE) method (FSGEE). Starting from an outlier-free initial subset of the data selected using a robust method, FSGEE makes its progress to the next subset by expanding the subset according to the distance of the observations to the GEE model fitted from the current subset. Through monitoring statistical diagnostics during the forward search process, the forward plots are produced by plotting the diagnostics against the sizes of the forward search subsets. The MS effects can then be discovered by simply investigating the forward plots of residuals. When the inclusion of an observation affects the model and the diagnostics of other points significantly, the observation is suspected to be an outlier. When necessary, by examining the forward plots of various statistical diagnostics, a deeper understanding of the observation can be acknowledged, for example changes in the values of the coefficients after the observation is included, or changes in the diagnostics of other observations when the suspicious outlier is removed from the data set. The acknowledgement will help in deciding whether the observation is a true outlier, or just a non-outlying observation with relatively high leverage. Through simulation studies and the analysis of seizure data and hormone data, the forward search of the GEE method is shown to be able to provide a wealth of information for guiding both outlier detection and the identification of MS effects.published_or_final_versionStatistics and Actuarial ScienceMasterMaster of Philosoph

Unaltered Angiogenesis-Regulating Activities of Platelets in Mild Type 2 Diabetes Mellitus despite a Marked Platelet Hyperreactivity.

Type 2 diabetes mellitus (T2DM) is associated with platelet dysfunction and impaired angiogenesis. Aim of the study is to investigate if platelet dysfunction might hamper platelet angiogenic activities in T2DM patients. Sixteen T2DM patients and gender/age-matched non-diabetic controls were studied. Flow cytometry and endothelial colony forming cell (ECFC) tube formation on matrigel were used to assess platelet reactivity and angiogenic activity, respectively. Thrombin receptor PAR1-activating peptide (PAR1-AP) induced higher platelet P-selectin expression, and evoked more rapid and intense platelet annexin V binding in T2DM patients, seen as a more rapid increase of annexin V+ platelets (24.3±6.4% vs 12.6±3.8% in control at 2 min) and a higher elevation (30.9±5.1% vs 24.3±3.0% at 8 min). However, PAR1-AP and PAR4-AP induced similar releases of angiogenic regulators from platelets, and both stimuli evoked platelet release of platelet angiogenic regulators to similar extents in T2DM and control subjects. Thus, PAR1-stimulated platelet releasate (PAR1-PR) and PAR4-PR similarly enhanced capillary-like network/tube formation of ECFCs, and the enhancements did not differ between T2DM and control subjects. Direct supplementation of platelets to ECFCs at the ratio of 1:200 enhanced ECFC tube formation even more markedly, leading to approximately 100% increases of the total branch points of ECFC tube formation, for which the enhancements were also similar between patients and controls. In conclusion, platelets from T2DM subjects are hyperreactive. Platelet activation induced by high doses of PAR1-AP, however, results in similar releases of angiogenic regulators in mild T2DM and control subjects. Platelets from T2DM and control subjects also demonstrate similar enhancements on ECFC angiogenic activities

Platelet-lymphocyte co-culture serves as an ex vivo platform of dynamic heterotypic cross-talk

Platelets are well known for their roles in hemostasis and thrombosis, and are increasingly recognized for their abilities to interact with white blood cells during inflammatory diseases, via secreted soluble factors as well as cell-cell contact. This interaction has been investigated in animal models and patient samples and has shown to be implicated in patient outcomes in several diseases. Platelet leukocyte co-cultures are widely used to study platelet-leukocyte interactions ex vivo. However, there is a paucity with regard to the systematic characterization of cell activation and functional behaviors of platelets and leukocytes in these co cultures. Hence we aimed to characterize a model of platelet-leukocyte co-culture ex vivo. Human peripheral blood mononuclear cell (PBMC) and platelets were isolated and co-cultured for 5 days at 37°C in the presence or absence of anti CD3/CD28 antibodies or PHA. We evaluated PF-4 secretion and p-selectin expression in platelets as markers of platelet activation. Lymphocyte activation was assessed by cell proliferation and cell population phenotyping, in addition to platelet-lymphocyte aggregation. Platelet secretion and p-selectin expression is maintained throughout the co-culture, indicating that platelets were viable and reactive over the 5 days . Similarly PBMCs were viable and maintained proliferative capacity. Finally, dynamic heterotypic conjugation between platelets and T lymphocytes was also observed throughout co-culture (with a peak at days 3 and 4) upon T lymphocyte activation. In conclusion, this in vitro model can successfully mimic the in vivo interaction between platelets and T lymphocytes, and can be used to confirm and/or support in vivo results