Neuromonitoring with microdialysis in severe traumatic brain injury patients.

BACKGROUND: Neuromonitoring with microdialysis has the potential for early detection of metabolic derangements associated with TBI. METHODS: 1,260 microdialysis samples from 12 TBI patients were analyzed for glucose, -lactate, pyruvate, lactate/pyruvate ratio (LPR), and lactate/glucose ratio (LGR). Analytes were correlated with the Glasgow Coma Scale (GCS) before surgery and with the Glasgow Outcome Scale (GOS) at the time of discharge. The patients were divided into two groups for GCS: 3-6 and 7-9, and for GOS 1-3 and 4-5. Chi-squared test was performed for correlations. RESULTS: Glucose, lactate levels, and LGR were high in TBI patients with GCS 3-6 (p < 0.0001). Pyruvate level was lower in patients with GCS 7-9 (p < 0.001). LPR was higher in patients with GCS 3-6 (p < 0.05). High glucose, lactate level (p < 0.001), and LPR (p < 0.01) was observed in patients with GOS 1-3. Pyruvate level was low in patients with GOS 1-3 (p < 0.001). LGR was higher in patient with better outcome (GOS 4-5). CONCLUSION: After craniotomy extracellular glucose and lactate were good "biomarkers" of cerebral damage in TBI patients. We consider that high extracellular lactate and low glucose is an indicator of severe neurological damage and poor outcome, because of impaired brain metabolism.

Antiphospholipid antibodies: paradigm in transition.

OBJECTIVES: This is a critical review of anti-phospholipid antibodies (aPL). Most prior reviews focus on the aPL syndrome (APS), a thrombotic condition often marked by neurological disturbance. We bring to attention recent evidence that aPL may be equally relevant to non-thrombotic autoimmune conditions, notably, multiple sclerosis and ITP. ORGANIZATION: After a brief history, the recent proliferation of aPL target antigens is reviewed. The implication is that many more exist. Theories of aPL in thrombosis are then reviewed, concluding that all have merit but that aPL may have more diverse pathological consequences than now recognized. Next, conflicting results are explained by methodological differences. The lupus anticoagulant (LA) is then discussed. LA is the best predictor of thrombosis, but why this is true is not settled. Finally, aPL in non-thrombotic disorders is reviewed. CONCLUSION: The current paradigm of aPL holds that they are important in thrombosis, but they may have much wider clinical significance, possibly of special interest in neurology.

Potential roles of cell-derived microparticles in ischemic brain disease.

PURPOSE: The objective of this study is to review the role of cell-derived microparticles in ischemic cerebrovascular diseases. MATERIALS AND METHODS: An extensive PubMed search of literature pertaining to this study was performed in April 2009 using specific keyword search terms related to cell-derived microparticles and ischemic stroke. Some references are not cited here as it is not possible to be all inclusive or due to space limitation. DISCUSSION: Cell-derived microparticles are small membranous vesicles released from the plasma membranes of platelets, leukocytes, red cells and endothelial cells in response to diverse biochemical agents or mechanical stresses. They are the main carriers of circulating tissue factor, the principal initiator of intravascular thrombosis, and are implicated in a variety of thrombotic and inflammatory disorders. This review outlines evidence suggesting that cell-derived microparticles are involved predominantly with microvascular, as opposed to macrovascular, thrombosis. More specifically, cell-derived microparticles may substantially contribute to ischemic brain disease in several settings, as well as to neuroinflammatory conditions. CONCLUSION: If further work confirms this hypothesis, novel therapeutic strategies for minimizing cell-derived microparticles-mediated ischemia are available or can be developed, as discussed.

Platelet activation rather than endothelial injury identifies risk of thrombosis in subjects positive for antiphospholipid antibodies.

BACKGROUND: Anti-phospholipid antibodies (APLA) are often associated with thrombosis, defining the antiphospholipid syndrome (APS) but it remains unclear why many subjects who are positive for APLA chiefly anti-cardiolipin (aCL) or anti-beta2GPI (abeta2GPI) do not develop thrombosis. A related question addressed in this study is whether the target of cellular injury in APS is predominately platelets or endothelial cells (EC). METHODS: aCL and abeta2GPI were determined by ELISA in 88 patients, 60 of whom were thrombotic and 28 non-thrombotic. Platelet activation was measured by CD62P and by concentration of platelet microparticles (PMP) and EC activation was assessed by endothelial microparticles (EMP), both by flow cytometry. Lupus anticoagulant (LAC) was measured in the hospital laboratory. RESULTS: There was no difference in frequency of aCL or abeta2GPI, neither IgG or IgM, between the thrombotic and non-thrombotic groups. Both groups showed elevated EMP compared to controls but this did not differ between thrombotic and non-thrombotic groups. In contrast, PMP were not significantly elevated in non-thrombotic but were elevated in thrombotic compared to non-thrombotic (p=0.03) and controls. CD62P, an independent marker of platelet activation, was also elevated in thrombotic vs. non-thrombotic. There was a trend for increased LAC in the thrombotic group but not significant. CONCLUSION: Although all subjects had evidence of endothelial activation, only platelet activation differed between thrombotic and non-thrombotic. This supports the hypothesis that platelet activation predisposes to thrombosis in the presence of chronic EC activation. These data also raise the possibility of distinguishing risk-prone APLA-positive individuals.

Clinical and neuroimaging correlates of antiphospholipid antibodies in multiple sclerosis: a preliminary study.

BACKGROUND: The presence of antiphospholipid antibodies (APLA) in multiple sclerosis (MS) patients has been reported frequently but no clear relationship between APLA and the clinical and neuroimaging features of MS have heretofore been shown. We assessed the clinical and neuroimaging features of MS patients with plasma APLA. METHODS: A consecutive cohort of 24 subjects with relapsing-remitting (RR) MS were studied of whom 7 were in remission (Rem) and 17 in exacerbation (Exc). All subjects were examined and underwent MRI of brain. Patients' plasma was tested by standard ELISA for the presence of both IgM and IgG antibodies using a panel of 6 targets: cardiolipin (CL), beta2 glycoprotein I (beta2GPI), Factor VII/VIIa (FVIIa), phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidylethanolamine (PE). RESULTS: In exacerbation up to 80% of MS subjects had elevated titers of IgM antibodies directed against the above antigens. However, in remission, less than half of MS patients had elevated titers of IgM antibodies against one or more of the above antigens. This difference was significant, p < 0.01, for all 6 target antigens. Interestingly, none of the MS patients had elevated plasma titers of IgG against any of the target antigens tested. Correlation analysis between MRI enhancing lesions and plasma levels of APLA revealed high correlation for aPC, aPS and aFVIIa (p

Life-threatening hypercoagulable state following splenectomy in ITP: successful management with aggressive antithrombotic therapy and danazol.

A life-threatening hypercoagulable state (HCS) is reported that developed after splenectomy in idiopathic thrombocytopenic purpura (ITP). A 50-year-old active male was rejected for blood donation because of an incidental finding of low platelet counts, 40,000/uL. The diagnosis was ITP. Although asymptomatic, he underwent splenectomy because of poor response to steroids and intravenous (IV) gamma globulin. One month after splenectomy, he suffered pulmonary emboli without deep venous embolism (DVT), followed by bilateral DVT, threatening amputation of the legs. Emergency thrombolysis, insertion of stent, and IV heparin saved his legs. Extensive workup for HCS was negative. IV heparin was withheld for colonoscopy for possible gastrointestinal neoplasm, at which time DVT recurred, necessitating another thrombolysis and heparin infusion. He was discharged on enoxaparin, antiplatelet therapy, and danazol. Platelet hyperactivation, characterized by high platelet microparticles (PMP) and CD62P, was present throughout his course of active ITP, resolving when ITP went into remission with danazol therapy. ITP has remained in remission for 4 years after stopping enoxaparin and danazol. In vitro, his plasma in active ITP induced activation of normal platelets, generating PMP and inducing CD62p-positive platelets and platelet aggregates; his plasma from remission had no effect. This indicates the presence of a platelet activating factor, possibly anti-platelet antibodies. Splenectomy may have allowed procoagulant PMP to accumulate to high levels resulting in HCS. We advise awareness of thrombotic complications post-splenectomy in the subset of ITP patients who are largely asymptomatic and exhibit persisting platelet activation.

Differences of soluble CD40L in sera and plasma: implications on CD40L assay as a marker of thrombotic risk.

INTRODUCTION: Soluble CD40L (sCD40L) ELISA has emerged as a promising predictor of poor outcomes in acute coronary syndrome. Yet many blood processing techniques have been used with little consideration of their effect on the results. METHODS: We measured sCD40L by ELISA in 10 patients with thrombocytopenia and 12 with normal or high platelet counts and 8 healthy controls using three sampling techniques: serum clotted on ice (serum-I) or at room temperature (serum-RT) and platelet poor plasma (PPP). RESULTS: Serum-RT samples, compared to serum-I, gave significantly higher CD40L values (p=0.003), demonstrating that ex vivo sCD40L release by activated platelets is inhibited by cold temperature. Although serum-I and PPP were comparable in patients with normal platelet counts, serum-I gave significantly higher values than PPP in the thrombocytosis group (p=0.01), suggesting that cold inhibition is insufficient in the latter group. To estimate the fraction of sCD40L that was microparticle-bound CD40L (mp-CD40L), 16 samples underwent 0.1-microm filtration. 50.6% of sCD40L was mp-CD40L in serum-RT, whereas 21.3% and 29.9% were observed in serum-I and PPP, respectively. Lastly, plasma sCD40L was assayed in 46 patients with and 35 without thrombosis. Plasma sCD40L did not correlate with platelet count in non-thrombotic, non-inflammatory patients but did (p<0.01) in those with thrombosis. CONCLUSIONS: Sample processing and temperature profoundly affect sCD40L assay. Serum-I and PPP minimize the release of sCD40L ex vivo and better represent sCD40L in vivo. However, PPP may be preferable particularly in patients with thrombocytosis. The existence of mp-CD40L highlights the importance of centrifuge conditions.

Bilateral ballism following streptococcal infection, associated with psychiatric disorder and purpura.

A woman in her 30s was brought to the hospital with abnormal movements. Three months prior, the patient had exacerbation of the movements after an episode of recurrent pharyngitis. Neurological examination revealed, violent involuntary movement that affected both upper and lower limbs, hypotonia and ataxia. Other findings including emotional instability and involuntary movements were considered ballistic. Throat culture showed ß haemolytic streptococci, tonsillectomy and specific antibiotic improved bilateral ballism and psychiatic disorder. This is the first report of bilateral ballism poststreptococcal infection.

Cell-derived microparticles and exosomes in neuroinflammatory disorders.

All blood cells and the vascular endothelium shed microparticles (MP) from their plasma membranes when suitably stimulated, and assay of MP in patient blood has found increasing application to the monitoring of disease states. In addition, mounting evidence suggests that MP are not mere epiphenomena but play significant roles in the pathophysiology of thromboses, inflammation, and cancers. This chapter endeavors to summarize the limited number of studies thus far done on MP in neurological disorders such as multiple sclerosis (MS), transient ischemic attacks, and the neurological manifestations of antiphospholipid syndrome (APS). In addition, the chapter offers some plausible hypotheses on possible roles of MP in the pathophsyiology of these disorders, chiefly, the hypothesis that MP are indeed important participants in some neuropathologies, especially those which are ischemic in nature, but probably also inflammatory ones. The chapter also goes over the history and general principles of MP studies (e.g., assay methods and pitfalls), comparison with alternative methods (e.g., soluble markers of disease states), subclasses of MP (such as exosomes), and other topics aimed at helping readers to consider MP studies in their own clinical fields. Tables include a listing of bioactive agents known to be carried on MP, many of which were heretofore considered strictly soluble, and some of which can be transferred from cell to cell via MP vectors, for example certain cytokine receptors.

Platelet activation in Helicobacter pylori-associated idiopathic thrombocytopenic purpura: eradication reduces platelet activation but seldom improves platelet counts.

INTRODUCTION: It has been suggested that Helicobacter pylori eradication often increases platelet counts in patients with chronic idiopathic thrombocytopenic purpura (ITP). In addition, H. pylori has been shown to induce platelet activation (CD62p or P-selectin expression) in previous studies. We assessed the response of platelet count and CD62p expression after eradication therapy in patients with ITP and H. pylori infection. METHODS AND RESULTS: We prospectively studied 15 ITP patients diagnosed with H. pylori infection by serology and breath test. A follow-up breath test was used to document eradication. Two out of 15 patients showed improvement in platelet counts after 6 months, 1 of which may have had drug-induced thrombocytopenia. Overall, certain platelet response rate in our series was 6.7% (1/15). We found that platelet CD62p expression by flow cytometry was elevated in 10/15 (66.7%) H. pylori-infected patients, which is a statistically significant difference when compared with 3/33 (9.1%) control ITP patients seronegative for H. pylori (p = 0.002). In addition, eradication therapy decreased CD62p expression (p = 0.04). However, reduction in platelet activation was not associated with an increase in platelet counts (mean 72.4 x 10(9)/l before and 68.7 after therapy; p = 0.4). CONCLUSION: In our series, platelet activation was common in ITP patients with H. pylori, and eradication therapy decreased platelet activation but seldom increased platelet counts. Increased platelet CD62p expression is a putative link between chronic infections and atherosclerosis, but further study is needed to clarify the implications of our observation.

Antiphospholipid antibodies (APLA) in immune thrombocytopenic purpura (ITP) and antiphospholipid syndrome (APS).

Antiphospholipid antibodies (APLA) are associated with anti-phospholipid syndrome (APS), a thrombotic disorder, but they are also frequently detected in immune thrombocytopenic purpura (ITP), a bleeding disorder. To investigate possible differences of APLA between these two disorders, we assayed IgG and IgM APLA by ELISA in 21 patients with ITP and 33 with APS. The APLA reacting against two protein target antigens, beta(2)-glycoprotein 1 (beta2GP1) and FVII/VIIa, and four phospholipids [cardiolipin (CL), phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylethanolamine (PE)] as well as lupus anticoagulant (LA) were analyzed. We made the following observations: (i) IgG and IgM antibodies to beta2GP1 and IgM antibodies to FVII/VIIa were more common in APS than ITP, P < 0.05, while IgG antibodies against the phospholipids (aCL, aPC, aPS, aPE) were more common in ITP than APS, P < 0.05; (ii) multiple APLA > or =3 antigens) were more frequent in APS than ITP, P < 0.05; (iii) LA was frequently associated with APS but was absent in ITP; (iv) APLA is quite common in ITP: two-thirds were positive for at least one APLA. In summary, APLA are prevalent in ITP but their profile differs from APS. In APS, antibodies were predominantly against beta2GP1 and 80% had positive LA, while in ITP the APLA reacted most often with the phospholipids without LA. The difference in APLA may result in opposite clinical manifestations in two disorders.

Long-term remission from life-threatening hypercoagulable state associated with lupus anticoagulant (LA) following rituximab therapy.

Rituximab, a chimeric monoclonal CD20 antibody, is useful in the treatment of B-cell lymphomas and certain autoimmune diseases. We report a successful outcome of rituximab for life threatening hypercoagulable state associated with lupus anticoagulant (LA). A 30-year-old woman initially presented 10 years ago with DVT and positive serology for SLE and LA. While on Coumadin, she suffered from recurrent DVT in the legs and arms, pulmonary emboli, Budd-Chiari syndrome, mesenteric vein thrombosis, bone infarcts, recurrent strokes, and chronic ITP. All measures including plasmapheresis and monthly IV cyclophosphamide were of no benefit. She was recently admitted with spontaneous subdural hematoma with INR of 3.8. Upon discontinuation of anticoagulation for surgical drainage, she developed acute abdomen from thrombosis and recurrent DVT. Because she had failed prior standard measures, 4 weekly infusions of rituximab (375 mg/m2) were given following 2 rounds of plasmapheresis. Subsequently, she made a remarkable recovery over the next month and has been free of thrombosis on Coumadin for over 15 months. LA, IgM antibodies to cardiolipin, and B2GP1 were consistently positive. After rituximab therapy, LA became negative and IgM antibodies to cardiolipin decreased and ITP went into remission. Rituximab induced a lasting remission in a woman suffering from life-threatening hypercoagulable state associated with LA. Her clinical remission was associated with disappearance of LA.

Antiphospholipid antibodies and platelet activation as risk factors for thrombosis in thrombocythaemia.

INTRODUCTION: Risk factors for thrombosis (TB) in thrombocythaemia (TC) associated with myeloproliferative disorder (MPD) are not well defined. METHODS: We measured antiphospholipid antibodies (APLA) in 35 patients with TC associated with MPD. Fourteen had TB and 21 did not. We assayed IgG and IgM APLA by ELISA for 6 antigens: beta2GP1, cardiolipin (CL), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylethanolamine (PE) and FVII/VIIa, together with markers of activation of platelets (CD62P) and endothelium [endothelial microparticles (EMP)]. RESULTS: At least one positive APLA was detected in 66% of TC patients overall. The incidence was significantly higher in the TB subgroup (92.8%) than non-TB (47.6%, p < 0.05). Multiple APLA (positive for more than one antigen) were also more frequent in TB, for both IgG and IgM, for all 6 antigens tested (p < 0.05). However, IgM APLA predominated, being about 2-fold more frequently positive than IgG for all 6 antigens. Platelet CD62P was significantly higher in the TB group (p < 0.05). EMP did not differ between TB and non-TB. The most frequent thrombotic complication was recurring ischemic cerebral vascular accidents (ICVA), leading to progressive cognitive impairment. Venous TB often developed at unusual sites. Recurring and reversible TB were common features in TC. SUMMARY: This study suggests that APLA and platelet activation are risk factors for TB in TC. APLA are prevalent in TC, and IgM APLA predominated over IgG. Activation of platelets but not of endothelium may be consistent with the reversible and recurrent features of TB in TC.

Antiphospholipid antibodies in immune thrombocytopenic purpura tend to emerge in exacerbation and decline in remission.

Although the presence of antiphospholipid antibodies (APLA) in immune thrombocytopenic purpura (ITP) has been reported, their clinical significance is not clear. The present study investigated APLA profiles in relation to the clinical stages of ITP. We studied APLA in 40 patients in three stages of ITP: exacerbation/relapse (n=7), stable (n=14) and remission (n=19). Both IgG and IgM APLA to six target antigens were measured by enzyme-linked immunosorbent assay: beta2-glycoprotein 1 (beta2GP1), cardiolipin, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and factor VII/VIIa. The central finding was that APLA were common in ITP but differed significantly in disease stages, being highest in exacerbation (86% positive), intermediate in stable disease (57%) and lowest in remission (42%). In exacerbations, APLA were predominantly of IgG class, while in stable disease, IgM predominated. During remission, APLA often became undetectable. Both the frequency and titres of APLA were significantly higher during exacerbation than remission. An inverse correlation was found between platelet count and nearly all APLA (except beta2GP1). Sequential study of six patients revealed that APLA tended to emerge and rise with exacerbation, concurrently with new episodes of bleeding and became undetectable during remission. These findings raise the possibility that APLA may play a role in the exacerbation and remission of ITP or they may be a consequence of platelet destruction.

Factor VII/VIIa: a new antigen in the anti-phospholipid antibody syndrome.

We investigated antibodies to factor VII/VIIa (FVII/VIIa) and five other common target antigens in 33 patients with a history of anti-phospholipid syndrome (APS) and 50 healthy controls using an enzyme-linked immunosorbent assay (ELISA) technique. We found that antibody to FVII/VIIa, a previously unrecognized and common antigen in APS, was present in 67% of patients. Frequencies of antibodies to other target antigens were: anti-beta-2 glycoprotein 1 (anti-beta 2GP1), 88%; anti-cardiolipin (anti-CL), 76%; anti-phosphatidylethanolamine (anti-PE), 67%; anti-phosphatidylserine (anti-PS), 64%; and anti-phosphatidylcholine (anti-PC), 59%. Most patients had antibodies against multiple antigens, but a few were positive for only anti-beta 2GP1 (12%) or anti-CL (3%). Positivity for anti-FVII/VIIa was significantly associated with positivity for anti-PE, anti-PS and/or anti-PC (P < 0.05) but not anti-beta 2GP1. When frequencies of immunoglobulin G (IgG) versus immunoglobulin M (IgM) antibodies were compared, anti-beta 2GP1 IgG correlated with the lupus anticoagulant (P < 0.05) and was significantly more prevalent than IgM, but the reverse was seen for all other antigens. In arterial thrombosis, IgM was more prevalent for all antigens, and was significantly associated with FVII/VIIa, PE and PS, whereas in venous thrombosis, IgG was frequently prevalent, especially in association with FVII/VIIa, beta 2GP1 and CL. In summary, FVII/VIIa is a new and common antigen in APS. Anti-FVII/VIIa is often associated with anti-PE, anti-PS and anti-PC. The IgM class is more frequently associated with arterial thrombosis and the IgG class with venous thrombosis.