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Biomedical subjects

L A Valentino

Publications and source records attributed to L A Valentino.

At least 19 recordsLinked to original sources
PubMed2006

Needles and needleless devices for infusion of anti-haemophilic factor concentrate: impact on protein structure and function.

A poor response to the infusion of anti-haemophilic factor (AHF) concentrates used to control acute bleeding or prevent haemorrhage during surgery may have many causes, including the lack of functional activity of the infused protein concentrate. It is generally recommended to follow the manufacturers' instructions when administering the factor intravenously. For convenience, infusion sets with 23 gauge butterfly needles are packaged with the major brands of AHF concentrate. In hospitals, blunt connectors for i.v. infusion are becoming more prevalent to reduce the risk of needle stick injuries to both patients and hospital staff. The integrity of AHF infused using such devices has not been examined. We examined the possibility that passage of complex proteins such as AHF through such devices may result in alteration of the protein, rendering it inactive. The results presented here suggest that this is not the case; neither the structure nor the function of AHF protein products was adversely affected by the use of the needleless transfer device (NTD) or the needle types and sizes commonly used in clinical practice. Samples of factor VIII and factor IX AHF concentrate were passed through the B-D Blunt Plastic Cannula or 23, 27 and 30 gauge needles. No significant changes in electrophoretic mobility or coagulation activity were detected. Samples generally showed slightly increased coagulation activity when compared with the control in which the sample was passed directly out of the syringe with no device attached. These data indicate that the NTD and various needle gauges are acceptable for the infusion of AHF concentrate in a clinical setting. Furthermore, the use of small gauge needles has advantages that may improve adherence to rigorous factor replacement programmes.

Blood Coagulation↗
PubMed2006

Considerations in the evaluation of haemophilia patients for short-term prophylactic therapy: a paediatric and adult case study.

The long-term prophylactic administration of clotting factor concentrate in patients with haemophilia reduces bleeding events, slows joint deterioration, and improves quality of life. Prophylaxis can also be effective when used short-term to prevent or reduce bleeding associated with trauma, surgery, and athletic activities. While clinical trials are needed to establish the optimal length of prophylaxis following injury, several weeks and possibly months of treatment may be needed. Discontinuing therapy prematurely can result in rebleeding in the injured area.

Acute Disease↗
PubMed2006

Surgical excision of a giant pelvic pseudotumour in a patient with haemophilia A.

The development of pseudotumors represents one of the most challenging complications facing physicians who care for patients with hemophilia. The successful removal of the giant pseudotumor described in this case report was achieved by a multidisciplinary team and demonstrates that this approach, albeit associated with significant risk, may be curative.

Abdomen↗
PubMed2006

Histological changes in murine haemophilic synovitis: a quantitative grading system to assess blood-induced synovitis.

Haemophilia is a congenital disorder that results in frequent bleeding into joints, in which a chronic and debilitating arthritis develops. The presence of blood evokes an inflammatory and proliferative synovial reaction. Although the molecular mechanisms and biochemical pathways which underlie this disorder are not known, significant advances have been made by studying a murine model of human haemophilic synovitis. In order to better understand and correlate the pathological, molecular and biochemical changes, it has become necessary to grade the histological changes observed. Despite a search of the literature and review of relevant publications, none of the currently utilized schemes were appropriate, and therefore a novel grading scheme was developed. After review of over 1000 histological sections, six characteristic changes were identified: (i) synovial hyperplasia; (ii) vascularity; (iii) discolouration by haemosiderin; (iv) the presence of blood (erythrocytes); (v) villus formation; and (vi) cartilage erosion. Synovial hyperplasia and vascularity were present in variable amounts and were quantitatively scored (0-3), while the other changes were qualitatively scored as absent or present (0 or 1). Application of the grading scheme was tested and a high interobserver correlation (greater than 80%) was found. The scheme was easy to learn even by novices, with no prior experience. The availability of the histological grading scheme for murine synovitis will allow for precise evaluation of the pathological changes following joint bleeding, and facilitate correlations with molecular and biochemical changes that lead to these changes.

Adolescent↗
PubMed2005

Synovitis in a murine model of human factor VIII deficiency.

Recurrent joint bleeding is the most common musculoskeletal manifestation of haemophilia and leads to a target joint and synovitis. The pathobiology of haemophilic synovitis (HS) is not well understood. Here the histopathological changes that occur following haemarthrosis were examined in an animal model for human HS. After two haemarthrosis, there was soft tissue and joint swelling and histological changes of acute synovitis included infiltration of the sub-synovial layer by mononuclear cells and neutrophils, thickening of the synovial membrane with villus formation, and hyperplasia of blood vessels. Subacute changes were evident after three haemarthrosis; muscle atrophy was present and an intense mononuclear cell infiltrate filled the sub-synovial space. There was destruction of articular surfaces and loss of cartilage. Seventeen months after three haemarthrosis, chronic joint changes included gross deformity and loss of congruence due to dense fibrotic tissue filling the joint space. The mononuclear inflammatory cell infiltrate and thickened synovial membrane persisted. Pits and erosions of articular surfaces and sub-chondral cysts were present. There was fibro-cartilage and new bone formation. This model of human HS should be useful to fully evaluate the biochemical and molecular changes that occur following joint bleeding and to test novel therapeutics to prevent HS.

Acute Disease↗
PubMed2004

Central venous access devices in haemophilia.

Central venous access devices (CVADs) can facilitate repeated and/or urgent administration of coagulation factors in haemophilic patients. We conducted a systematic review and meta-analysis of complication rates and risk factors for poor outcome. Forty-eight studies with a total of 2704 patients and 2973 CVADs were included. The primary indications for CVADs were immune tolerance therapy (34.9% of patients), difficult venous access (31.8%) and prophylaxis (29.1%). Fully implanted CVADs were employed in 77.4% of cases and external CVADs in 22.6%. A total of 1190 infections were reported, and the pooled incidence of infection was 0.66 per 1000 CVAD days [confidence interval (CI), 0.44-0.97 per 1000 CVAD days]. Among patients developing infection, the pooled time to first infection was 295 days (CI, 181-479 days). Presence of inhibitors was an independent risk factor for infection with an incidence rate ratio (IRR) of 1.67 (CI, 1.15-2.43). Infection was less likely in patients >6 years of age (IRR, 0.46; CI, 0.27-0.79) and recipients of fully implanted CVADs (IRR, 0.31; CI, 0.12-0.86). Available information on thrombosis was limited, with only 55 cases being reported. Eventually, 31.3% of CVADs were removed, and infection was the reason for removal in 69.9% of cases and thrombosis in 4.1%. The pooled time period CVADs remained indwelling prior to removal or the expiration of the study observation period was 578 days per CVAD (CI, 456-733 days per CVAD). CVADs can confer major benefits in patients with haemophilia requiring long-term venous access, and serious complications are rare.

Catheterization, Central Venous↗
PubMed2004

Secondary prophylaxis therapy: what are the benefits, limitations and unknowns?

Prophylaxis is widely recommended for the management of severe haemophilia A. Adoption of this approach has varied from country to country, and notably in the US prophylaxis is currently administered in fewer than one-half of severe cases. One implication is that a substantial segment of the severe haemophilia. A population will only be able to reap the potential benefits of prophylaxis if administered in the form of secondary prophylaxis. This therapeutic alternative has been less extensively investigated than primary prophylaxis, but nevertheless sufficient evidence has been reported to allow an assessment of the benefits and limitations of secondary prophylaxis. This evidence addresses the use of secondary prophylaxis in three contexts: (i). early secondary prophylaxis; (ii). delayed secondary prophylaxis and (iii). secondary prophylaxis in adults. In patients receiving early secondary prophylaxis studies in Sweden, the Netherlands, the UK and the US have demonstrated a reduction in the frequency of bleeding episodes and a subsequent low incidence of arthropathy. Additional reported benefits consist of reduced emergency room visits and hospitalizations. However, secondary prophylaxis is associated with an increased risk of the eventual development of arthropathy compared with primary prophylaxis. When delayed until school age or adolescence or until the development of frequent bleeding episodes under on-demand treatment, secondary prophylaxis generally appears to be unable to reverse all existing or developing joint damage. Nevertheless, multiple studies have shown that this therapy can retard further joint deterioration, reduce the frequency of haemorrhage, hospitalization and missed school days, improve physical function and capacity for self care, lessen restrictions on activities, reduce pain and enhance quality of life. Secondary prophylaxis in adults has been shown effective in reducing bleeding episodes. Adults under secondary prophylaxis can also experience improvements in joint condition, functional capacity and quality of life and a reduction in pain. Irrespective of age at initiation, long-term secondary prophylaxis appears to reduce the frequency of bleeding episodes even in patients with existing target joints whose bleeding diathesis persists during the early phases of secondary prophylactic therapy. In light of its potential benefits for substantial numbers of patients with severe haemophilia A, secondary prophylaxis should be considered to as a therapeutic option for patients not receiving primary prophylaxis.

Adolescent↗
PubMed2004

Experimental haemophilic synovitis: rationale and development of a murine model of human factor VIII deficiency.

Haemophilia is a genetic disease as a result of the deficiency of blood coagulation factor VIII or IX. Bleeding is common, especially into joints where an inflammatory, proliferative synovitis develops resulting in a debilitating arthritis, haemophilic arthropathy. The pathogenesis of blood-induced haemophilic synovitis (HS) is poorly understood. The gross, microscopic and ultrastructural changes that occur in the synovial membrane following human and experimental hemarthrosis have been described. Repeated episodes of bleeding induce synoviocyte hypertrophy and hyperplasia, an intense neovascular response and inflammation of the synovial membrane. The component(s) in blood that initiates these changes is(are) not known, although iron is often proposed as one possibility. Here, we describe a novel murine model of human haemophilia A, which facilitates the examination of large number of animals and tissue specimens. The effects of hemarthrosis on the physical, gross and microscopic changes evoked following joint bleeding are described. Controlled, blunt trauma to the knee joint consistently resulted in joint swelling because of a combination of bleeding and inflammation. Hemosiderin was found in the synovial membrane. Similar to hemarthrosis in human haemophilia, joint bleeding resulted in acute morbidity evidenced by inactivity, weight loss and immobility. With time the animals recovered. The model of experimental murine HS described here has utility in the study of the pathogenesis of HS. This is the first of a series of articles, which will discuss the pathophysiology and characterize the model, with comparison of his model to others which have been published previously. It should provide a useful model to test potential therapeutic interventions.

Animals↗
PubMed2004

Consensus recommendations for use of central venous access devices in haemophilia.

Venous access is essential for delivery of haemophilia factor concentrate. Wherever possible, peripheral veins remain the route of choice, and the use of central venous access devices (CVADs) should be limited to cases of clear need in patients with caregivers able to exercise diligence in CVAD care and should continue no longer than necessary. CVADs are of recognized value for repeated administration of coagulation factors in haemophilia, particularly for prophylaxis and immune tolerance therapy and in young children. Evidence to guide best practices has been fragmentary, and standardized methods for CVAD usage have yet to be established. We have developed management recommendations based upon available published evidence as well as extensive clinical experience. These recommendations address patient and CVAD selection; CVAD placement, care and removal; caregiver/patient guidance; and complications, including infection and thrombosis. In the absence of inhibitors, ports are recommended, primarily because of fewer associated infections than with external catheters. For patients with inhibitors, ports also appear to be associated with fewer infections. Infection is the most frequent complication, and recommendations to prevent and treat infections are supported by extensive clinical data and experience. Strict adherence to handwashing and aseptic technique are essential elements of catheter care. Evidence-based data regarding the detection and treatment of CVAD-related thrombotic complications are limited. Caregiver education is an integral part of CVAD use and the procedural practices of users should be regularly re-assessed. These recommendations provide a basis for sound current CVAD practice and are expected to undergo further refinements as new evidence is compiled and clinical experience is gained.

Catheterization, Central Venous↗
PubMed2004

Transfusion-transmitted virus is not present in factor IX concentrates commonly used to treat haemophilia B.

Transfusion-transmitted virus (TTV) is a potential cause of post-transfusion hepatitis in patients with haemophilia. Plasma-derived clotting factor concentrates currently undergo processes that are effective in removal and inactivation of viruses such as HIV, hepatitis B and C; however, their effectiveness with respect to TTV is unknown. To determine if TTV DNA is present in plasma-derived concentrates of factor IX, we tested 14 lots of Mononine and compared the results with BeneFix. Nucleic acid isolation, followed by a two-round polymerase chain reaction (PCR) and agarose gel analysis indicated that all 17 lots were negative for TTV. Although TTV may be considered an emerging pathogen, no evidence of the virus was detected in the commercially available plasma-derived concentrate of FIX most commonly used to treat haemophilia B.

Circoviridae Infections↗
PubMed2001

Bruising and the ketogenic diet: evidence for diet-induced changes in platelet function.

Excessive bruising is a symptom noted by parents of some children treated with the ketogenic diet for epilepsy control, although this side effect is not reported in the literature. We evaluated our cohort of current and past diet-treated patients for symptoms of bruising or bleeding through chart review and prospective screening at clinic follow-up visits. A significant increase in bruising or other minor bleeding was reported and/or observed in 16 of 51 patients (31.4%). There were no differences in sex distribution or number of anticonvulsants used between patients with bruising/bleeding and those without this symptom, although the group with bruising/bleeding was significantly younger. No specific anticonvulsant was associated with bruising/bleeding. Six patients with diet-induced bruising/bleeding underwent an investigation for bleeding diathesis. Five of these patients had prolonged bleeding times and all had diminished responsiveness to various platelet aggregating agents, with no evidence of a release defect. The abnormalities all normalized in the 1 patient tested after ceasing the diet. No patients had serious hemorrhage. One patient had mild von Willebrand disease, which had been asymptomatic before diet initiation. Some patients were Stimate responsive, suggesting a treatment for more severe bouts of symptoms. These data suggest that a ketogenic diet-related bleeding tendency occurs in about one third of treated patients owing to preexisting factors defining susceptibility in combination with diet-induced depression of platelet responsiveness, possibly related to changes in platelet membrane lipid composition and/or concentration and resultant effects on function of membrane-embedded proteins. Patients on the diet undergoing anticoagulation or surgery should be evaluated carefully for symptoms of bleeding tendency.

Blood Platelets↗
PubMed1999

Atherosclerotic aortic gangliosides enhance integrin-mediated platelet adhesion to collagen.

Gangliosides, sialic acid-containing glycosphingolipids, accumulate in atherosclerotic vessels. Their role in the pathogenesis of atherosclerosis is unknown. Gangliosides isolated from tumor cells promote collagen-stimulated platelet aggregation and ATP secretion and enhance platelet adhesion to immobilized collagen. These activities are all mediated by ganglioside effects on the platelet integrin collagen receptor alpha2beta1. Therefore, we hypothesized that gangliosides isolated from atherosclerotic plaques would enhance platelet adhesion to immobilized collagen, a major component of the subendothelial matrix of blood vessels. Furthermore, we questioned whether this effect of atherosclerotic gangliosides might play a role in the pathogenesis of atherosclerosis. To test this hypothesis, we isolated the gangliosides from postmortem aortas of patients with extensive atherosclerotic disease and examined their effects on platelet adhesion. Samples of aortic tissue taken from areas involved with atherosclerotic plaque demonstrated accumulation of gangliosides (64.9+/-6.5 nmol/g wet weight) compared with gangliosides isolated from control normal aortic tissue taken from children who died of noncardiac causes (NAGs; 21.1+/-6.4 nmol/g wet weight). Interestingly, samples of tissue taken from diseased aortas but from areas not involved with gross plaque formation also demonstrated ganglioside accumulation (47.6+/-12.8 nmol/g wet weight). Next, the activity of each of these gangliosides on platelet adhesion to immobilized type I collagen was studied. Atherosclerotic aortic gangliosides (AAGs) as well as those isolated from grossly unaffected areas of the same aorta (UAGs) both increased platelet adhesion compared with control NAGs (OD570, 0. 37+/-0.11 and 0.29+/-0.14 versus 0.16+/-0.07, respectively; P<0.01 and P<0.05, respectively). These OD570 values corresponded to 9x10(5), 8x10(4), and 6x10(3) platelets per well after preincubation with 5 micromol/L AAG, UAG, and NAG, respectively. Increased adhesion was observed after preincubation with as little as 0.5 micromol/L AAG, and maximal adhesion was seen at 2.5 micromol/L, with a plateau extending to the highest concentration tested, 10 micromol/L. The effect of AAGs on platelet adhesion to collagen was abrogated by incubation of treated platelets with F-17 anti-alpha2 monoclonal antibody (OD570, 0.13+/-0.02). Finally, the effects of the major individual gangliosides isolated from atherosclerotic tissues, GM3 and GD3, were tested. GM3 increased adhesion to collagen (OD570, 0.415+/-0.06) as did GD3 (0.31+/-0.08). Similar to that of AAGs, the effect of both molecules was blocked by F-17 (0. 09+/-0.04 and 0.13+/-0.06, respectively). These experiments demonstrate that accumulated atherosclerotic gangliosides promote platelet adhesion to collagen, the major component of the subendothelial matrix. Furthermore, this activity is mediated by an effect of the gangliosides on the collagen-binding integrin alpha2beta1. This activity may provide a mechanism for the development of platelet thrombi at sites where atherosclerotic gangliosides accumulate and help to explain the role of platelets in the process of atherosclerotic disease progression.

Aged↗
PubMed1997

Effects of neuroblastoma tumor gangliosides on platelet adhesion to collagen.

Gangliosides, sialic acid-containing glycosphingolipids, enhance tumor formation in experimental animals and are associated with tumor progression and metastasis in humans. The mechanism(s) for this activity is (are) unknown. One possibility is enhanced platelet activation, since the interaction of platelets with tumor cells contributes to tumor cell arrest in the vascular compartment. We have previously shown that neuroblastoma tumor gangliosides (NBTG) enhance platelet adenosine triphosphate (ATP) secretion, aggregation, and adhesion. We determined that these NBTG effects are specific for collagen and are mediated through an alpha2 beta1 integrin-dependent mechanism. This report describes the effects of NBTG on a physiologically relevant model of collagen-alpha2 betal interaction. Platelet adhesion to immobilized native collagen fibers similar to those found in the extracellular matrix of blood vessels was determined. Platelet adhesion is enhanced by NBTG in a concentration-dependent manner. Incubation with concentrations of 1 and 10 microM NBTG increased platelet adhesion by 9% and 52%, respectively, compared to less than 1% in controls not incubated with gangliosides (P = 0.001 and P < 0.0001, respectively). In addition to increasing the number of adherent platelets, NBTG promoted more rapid attachment. In NBTG-incubated platelets, platelet adhesion began after a 5-min lag phase and was maximal at 30 min compared to a 20-min lag phase and maximal adhesion at 60 min for control platelets. At 30 min this difference was significant (P = 0.017); however, by 120 min there was no difference between NBTG and controls (P = 0.259). NBTG also induces platelet adhesion at collagen concentrations (0.1 microg) that failed to support adhesion of control platelets. These effects of NBTG require Mg2+ or Mn2+ ions but are not supported by Zn2+ or Ca2+ ions. Furthermore, preincubation of platelets with a blocking antibody (6F1) to the integrin collagen receptor alpha2 beta1 abrogates all of the effects of NBTG. These results indicate that tumor gangliosides enhance platelet adhesion to extracellular matrix collagen and promote rapid stabilization of the collagen-alpha2 beta1 interaction, the initial steps in platelet activation.

Adenosine Triphosphate↗
PubMed1996

Tumor gangliosides enhance alpha2 beta1 integrin-dependent platelet activation.

Gangliosides, sialic acid-containing glycosphingolipids, enhance platelet adhesion to collagen and consequent platelet activation. For example, gangliosides shed by neuroblastoma tumor cells (NBTG) added to a subthreshold (non-activating) concentration (1 microgram/ml) of collagen, cause platelet aggregation (59 +/- 10%) and ATP release (2.3 +/- 0.2 nmol) equivalent to that caused by 10 micrograms/ml collagen alone. Here we report further studies to characterize this effect. Platelet aggregation and ATP release were not induced by NBTG in combination with subthreshold concentrations of adenosine diphosphate, epinephrine, thrombin or arachidonic acid, suggesting that NBTG specifically influences collagen-mediated platelet activation. Maximal platelet aggregation and ATP release required extracellular magnesium and only a short (1 min) preincubation with NBTG, suggesting a collagen receptor-mediated mechanism of this ganglioside activity. Since gangliosides interact with several integrin receptors, we determined whether NBTG influences alpha 2 beta 1, a major integrin collagen receptor on platelets. Incubation of platelets with a monoclonal antibody directed against the alpha 2 chain (5E8) blocked the increase in platelet aggregation (9 +/- 3% vs. 80 +/- 2%) and ATP release ( < 0.2 vs 2.5 +/- 0.1 nmol) induced by NBTG and 1 microgram/ml collagen. Incubation with an antibody to the non-integrin collagen receptor, CD36, or with an isotype control antibody did not abrogate the effect of NBTG. Finally, NBTG and its major component, GD2, enhanced alpha 2 beta 1-mediated platelet adhesion to immobilized collagen in an antibody 5E8-inhibitable manner. These findings implicate the alpha 2 beta 1-collagen interaction as a target of the effect of tumor-derived gangliosides.

Cations, Divalent↗
PubMed1996

beta-Glucuronidase P408S, P415L mutations: evidence that both mutations combine to produce an MPS VII allele in certain Mexican patients.

Mucopolysaccharidosis type VII (MPS VII, Sly syndrome) is an autosomal recessively inherited lysosomal storage disease caused by a deficiency in beta-glucuronidase. We identified and studied a novel allele containing two C-to-T transitions resulting in P408S and P415L alterations, which is present in homozygous state in one Mexican patient and in heterozygous state in another. None of the previous reports describing mutations in the MPS VII gene include Mexican patients. Expression of either of the mutations individually showed only modest effects on the properties of the enzyme. However, expression of the doubly mutant allele resulted in markedly reduced activity and rapid degradation in an early biosynthetic compartment.

Animals↗
PubMed1995

Tandem peripheral blood progenitor cell transplants as initial therapy for metastatic breast cancer.

PURPOSE: To investigate the use of two sequential courses of high-dose chemotherapy and peripheral blood progenitor cell (PBPC) transplant as initial therapy for patients with untreated metastatic breast cancer. The goal of the study was to maximize treatment intensity through the use of two non-cross-resistant regimens, each equal in intensity to that used in single transplants. METHODS: PBPC were collected after a course of granulocyte colony-stimulating factor (G-CSF) only or of cyclophosphamide, etoposide, and G-CSF. The first transplant regimen consisted of thiotepa (600 mg/m2), cyclophosphamide (6000 mg/m2), and carboplatin (800 mg/m2). After recovery from the first transplant, responding patients received a second course of therapy consisting of busulfan (16 mg/kg) and etoposide (60 mg/kg). RESULTS: Forty-four patients were enrolled. Five patients did not proceed to transplantation due to tumor progression during PBPC mobilization. Five patients achieved complete response after the first transplant, and 14 were in complete remission at the end of the therapy. Six patients remain free of disease after a median followup of 22 months (range 12-27+ months). The 2-year event-free survival for complete responders is 25.4% (standard error 14.4%). Engraftment was prompt, with a median of 8 and 13 days, respectively, to reach a neutrophil count of 500/mm3 and a platelet count of 50,000/mm3. As a result of the gastrointestinal toxicity of the first course, the median interval between transplants was 68 days. The toxicities of the second transplant course were principally hepatic and muco-cutaneous. Hepatic veno-occlusive disease occurred in 12 patients and was a contributor to the death of three. CONCLUSIONS: Rapid hematologic recovery achieved with PBPC made possible the administration of two courses of high-dose chemotherapy without compromising the intensity of either transplant regimen. The adverse effects of the second course, however, were substantially higher than predicted. The outcome of patients achieving a complete response is promising. Overall, the antitumor benefit of this approach in patients with previously untreated metastatic disease was not superior to that achieved with single transplants in patients responding to standard-dose chemotherapy.

Adult↗
PubMed1994

Circulating tumor gangliosides enhance platelet activation.

Gangliosides enhance tumor formation in experimental animals, and high circulating concentrations of gangliosides shed by tumor cells are associated with rapid progression of human neuroblastoma. We studied these shed molecules for effects on platelet function, because platelet activation may play a role in the metastatic process. Preincubation of normal platelets in patient (tumor ganglioside-containing) serum resulted in their aggregation upon exposure to a subthreshold concentration (1 microgram/mL) of collagen (up to 34% v < 10% in normal serum) and ATP release (up to 1.1 nmol/2.5 x 10(7) platelets v < 0.2 in normal serum). Because circulating shed tumor gangliosides are lipoprotein-associated, we next assessed the effects of the serum lipoprotein fraction on platelet ATP release. The patient serum lipoprotein fraction (d > 1.210) enhanced ATP release (up to 3.1 nmol ATP), whereas the same fraction of normal serum, and both patient and control lipoprotein-depleted serum fractions (d > 1.210), were inactive (< 0.2 nmol ATP released). Finally, as little as 0.5 mumol/L patient serum gangliosides (purified from the lipoprotein fraction) caused significantly greater ATP release than did normal serum gangliosides (P < .01) and caused maximal release at 50 mumol/L (up to 3.0 nmol ATP released v < or = 0.3 nmol released by platelets exposed to normal serum gangliosides). Purified total human neuroblastoma tumor gangliosides, detected in the patient serum and isolated from LA-N5 cells, were highly active; preincubation of platelets with only 5 mumol/L of these gangliosides resulted in release of 2.5 +/- 0.1 nmol ATP. Thus, neuroblastoma patient serum, the lipoprotein fraction, and, specifically, the serum gangliosides enhance platelet activation. This activity appears to reside particularly in the tumor cell gangliosides, which are shed in vivo.

Adenosine Triphosphate↗