Changes in inflammatory mediators following eccentric exercise of the elbow flexors

The aims of this study were to examine the plasma concentrations of inflammatory mediators including cytokines induced by a single bout of eccentric exercise and again 4 weeks later by a second bout of eccentric exercise of the same muscle group. Ten untrained male subjects performed two bouts of the eccentric exercise involving the elbow flexors (6 sets of 5 repetitions) separated by four weeks. Changes in muscle soreness, swelling, and function following exercise were compared between the bouts. Blood was sampled before, immediately after, 1 h, 3 h, 6 h, 24 h (1 d), 48 h (2 d), 72 h (3 d), 96 h (4 d) following exercise bout to measure plasma creatine kinase (CK) activity, plasma concentrations of myoglobin (Mb), interleukin (IL)-1 beta, IL-1 receptor antagonist (IL-1ra), IL-4, IL-6, IL-8, IL-10, IL-12p40, tumor necrosis factor (TNF)-alpha, granulocyte colony-stimulating factor (G-CSF), myeloperoxidase (MPO), prostaglandin E-2 (PGE(2)), heat shock protein (HSP) 60 and 70. After the first bout, muscle soreness increased significantly, and there was also significant increase in upper arm circumference; muscle function decreased and plasma CK activity and Mb concentration increased significantly. These changes were significantly smaller after the second bout compared to the first bout, indicating muscle adaptation to the repeated bouts of the eccentric exercise. Despite the evidence of greater muscle damage after the first bout, the changes in cytokines and other inflammatory mediators were quite minor, and considerably smaller than that following endurance exercise. These results suggest that eccentric exercise-induced muscle damage is not associated with the significant release of cytokines into the systemic circulation. After the first bout, plasma G-CSF concentration showed a small but significant increase, whereas TNF-alpha and IL-8 showed significant decreases compared to the pre-exercise values. After the second bout, there was a significant increase in IL-10, and a significant decrease in IL-8. In conclusion, although there was evidence of severe muscle damage after the eccentric exercise, this muscle damage was not accompanied by any large changes in plasma cytokine concentrations. The minor changes in systemic cytokine concentration found in this study might reflect more rapid clearance from the circulation, or a lack of any significant metabolic or oxidative demands during this particular mode of exercise. In relation to the adaptation to the muscle damage, the anti-inflammatory cytokine IL-10 might work as one of the underlying mechanisms of action.

Effect of early malnutrition and environmental stimulation in the performance of rats in the elevated plus maze

Malnourished rats since birth (mothers fed on 6% of protein) or controlled ones (16% of protein), half of each group received environmental stimulation (ES) from the age of 0-35th day, were studied. The performance in the elevated plus maze (EPM) was assessed on the last day. ES increased time spent and also the entries into open arms of EPM, but malnourished non-stimulated rats visited more segments near the central area than the distant ones. Data suggests an anxiolytic effect of ES which is less evident in malnourished rats. (C) 2009 Elsevier B.V. All rights reserved.

Impact of photodynamic therapy on inflammatory cells during human chronic periodontitis

The aim of this study was to evaluate the effects of the photodynamic therapy (PDT) on the inflammatory infiltrate and on the collagen network organization in human advanced chronic periodontitis Two different drug delivery systems (DDS) were tested (liposomes and nanoemulsions) to determine if the effects of PDT could differ according to the DDS used Sixteen patients presenting two teeth with chronic advanced periodontitis and Important tooth mobility with clinical indication of extraction were included in the group liposomes (group L n = 8) or in the group nanoemulsions (group N n = 8) in order to compare the effects of each DDS Seven days before extractions one tooth of each patient was treated with PDT using phthalocyanine derivatives as photosensitizers and the contralateral tooth was taken as control In group L the density of gingival collagen fibers (66 +/- 19%) was significantly Increased (p < 0 02) when compared to controls (35 +/- 21%) Concerning the antigen-presenting cells PDT had differential effects depending on the drug delivery system the number of macrophages was significantly decreased (p < 0 05) in group L while the number of Langerhans cells was significantly decreased in group N (p < 0 02) These findings demonstrate that PDT presents an impact on gingival Inflammatory phenomenon during chronic periodontitis and leads to a specific decrease of antigen-presenting cells populations according to the drug delivery system used (C) 2010 Elsevier B V All rights reserved

Numerical modelling of chemical effects of magma solidification problems in porous rocks

The solidification of intruded magma in porous rocks can result in the following two consequences: (1) the heat release due to the solidification of the interface between the rock and intruded magma and (2) the mass release of the volatile fluids in the region where the intruded magma is solidified into the rock. Traditionally, the intruded magma solidification problem is treated as a moving interface (i.e. the solidification interface between the rock and intruded magma) problem to consider these consequences in conventional numerical methods. This paper presents an alternative new approach to simulate thermal and chemical consequences/effects of magma intrusion in geological systems, which are composed of porous rocks. In the proposed new approach and algorithm, the original magma solidification problem with a moving boundary between the rock and intruded magma is transformed into a new problem without the moving boundary but with the proposed mass source and physically equivalent heat source. The major advantage in using the proposed equivalent algorithm is that a fixed mesh of finite elements with a variable integration time-step can be employed to simulate the consequences and effects of the intruded magma solidification using the conventional finite element method. The correctness and usefulness of the proposed equivalent algorithm have been demonstrated by a benchmark magma solidification problem. Copyright (c) 2005 John Wiley & Sons, Ltd.

Characterization of inflammatory responses to eccentric exercise in humans

Eccentric exercise commonly results in muscle damage. The primary sequence of events leading to exercise-induced muscle damage is believed to involve initial mechanical disruption of sarcomeres, followed by impaired excitation-contraction coupling and calcium signaling, and finally, activation of calcium-sensitive degradation pathways. Muscle damage is characterized by ultrastructural changes to muscle architecture, increased muscle proteins and enzymes in the bloodstream, loss of muscular strength and range of motion and muscle soreness. The inflammatory response to exercise-induced muscle damage is characterized by leukocyte infiltration and production of pro-inflammatory cytokines within damaged muscle tissue, systemic release of leukocytes and cytokines, in addition to alterations in leukocyte receptor expression and functional activity. Current evidence suggests that inflammatory responses to muscle damage are dependent on the type of eccentric exercise, previous eccentric loading (repeated bouts), age and gender. Circulating neutrophil counts and systemic cytokine responses are greater after eccentric exercise using a large muscle mass (e.g. downhill running, eccentric cycling) than after other types of eccentric exercise involving a smaller muscle mass. After an initial bout of eccentric exercise, circulating leukocyte counts and cell surface receptor expression are attenuated. Leukocyte and cytokine responses to eccentric exercise are impaired in elderly individuals, while cellular infiltration into skeletal muscle is greater in human females than males after eccentric exercise. Whether alterations in intracellular calcium homeostasis influence inflammatory responses to muscle damage is uncertain. Furthermore, the effects of antioxidant supplements are variable, and the limited data available indicates that anti-inflammatory drugs largely have no influence on inflammatory responses to eccentric exercise. In this review, we compare local versus systemic inflammatory responses, and discuss some of the possible mechanisms regulating the inflammatory responses to exercise-induced muscle damage in humans.

Influence of Lactic Acid on Endogenous and Viral RNA-Induced Immune Mediator Production by Vaginal Epithelial Cells

OBJECTIVE: To evaluate the influence of lactic acid on immune mediator release from vaginal epithelial cells. METHODS: The human vaginal epithelial cell line, VK2/E6E7, was cultured in the presence or absence of physiological concentrations of lactic acid, and in the presence or absence of the viral Toll-like receptor 3 agonist, poly (inosinic acid: cytidylic acid). Supernatants were assayed by enzyme-linked immunosorbent assay (ELISA) for interleukin (IL)-1 beta, IL-6, IL-8, IL-23, transforming growth factor (TGF)-beta and secretory leukocyte protease inhibitor. RESULTS: Vaginal epithelial cells spontaneously released IL-1 beta (25.9 pg/mL), IL-8 (1.0 ng/mL), TGF-beta (175 pg/mL), and secretory leukocyte protease inhibitor (33.8 ng/mL). Only TGF-beta production was marginally enhanced (49%) by addition of lactic acid alone. Poly (inosinic acid: cytidylic acid) by itself stimulated the release of IL-6 (305 pg/mL) and enhanced IL-8 production (2.8 ng/mL). The combination of poly (inosinic acid: cytidylic acid) and lactic acid markedly increased IL-8 production (5.0 ng/mL) and induced the release of IL-1 beta (96.2 pg/mL). The poly (inosinic acid: cytidylic acid)-mediated lactic acid effect on IL-1 beta and IL-8 release was abrogated when the lactic acid was neutralized or if acetic acid was substituted for lactic acid. CONCLUSION: Lactic acid enhances the release of selective mediators from vaginal epithelial cells and stimulates antiviral immune responses. (Obstet Gynecol 2011;118:840-6) DOI: 10.1097/AOG.0b013e31822da9e9

Potassium in Hemorrhagic Shock: A Potential Marker of Tissue Hypoxia

Background: This study was designed to evaluate serum potassium level variation in a porcine model of hemorrhagic shock ( HS). Methods: Eight pigs were studied in a controlled hemorrhage model of HS. Blood withdrawal began at a 50 mL/min to 70 mL/min rate, adjusted to reach a mean arterial pressure ( MAP) level of 60 mm Hg in 10 minutes. When MAP reached 60 mm Hg, the blood withdrawal rate was adjusted to maintain a MAP decrease rate of 10 mm Hg every 2 minutes to 4 minutes. Arterial and mixed venous blood samples were collected at MAP levels of 60 mm Hg, 50 mm Hg, 40 mm Hg, 30 mm Hg, 20 mm Hg, and 10 mm Hg and analyzed for oxygen saturation, PO(2), PCO(2), potassium, lactate, bicarbonate, hemoglobin, pH, and standard base excess. Results: Significant increase in serum potassium occurred early in all animals. The rate of rise in serum potassium and its levels accompanied the hemodynamic deterioration. Hyperkalemia ( K >5 mmol/L) incidence was 12.5% at 60 mm Hg and 50 mm Hg, 62.5% at 40 mm Hg, 87.5% at 30 mm Hg, and 100% at 20 mm Hg. Strong correlations were found between potassium levels and lactate ( R = 0.82), SvO(2) ( R = 0.87), Delta pH ( R = 0.83), and Delta PCO(2) ( R = 0.82). Conclusions: Serum potassium increase accompanies the onset of HS. The rise in serum potassium was directly related to the hemodynamic deterioration of HS and strongly correlated with markers of tissue hypoxia.

Biologically active conformer of the effector region of human C5a and modulatory effects of N-terminal receptor binding determinants on activity

A conformationally biased decapeptide agonist of human C5a (C5a(65-74)Y65,F67,P69,P71,D-Ala73 or YSFKPMPLaR) was used as a functional probe of the C5a receptor (C5aR) in order to understand the conformational features in the C-terminal effector region of C5a that are important for C5aR binding and signal transduction. YSFKPMPLaR was a potent, full agonist of C5a, but at higher concentrations had a superefficacious effect compared to the natural factor. The maximal efficacy of this analogue was 216 +/- 56% that of C5a in stimulating the release of beta-glucuronidase from human neutrophils. C5aR activation and binding curves both occurred in the same concentration range with YSFKPMPLaR, characteristics not observed with natural C5a or more conformationally flexible C-terminal agonists. YSFKPMPLaR was then used as a C-terminal effector template onto which was synthesized various C5aR binding determinants from the N-terminal core domain of the natural factor. In general, the presence of N-terminal binding determinants had little effect on either potency or binding affinity when the C-terminal effector region was presented to the C5aR in this biologically active conformation. However, one peptide, C5a(12-20)-Ahx-YSFKPMPLaR, expressed a 100-fold increase in affinity for the neutrophil C5aR and a 6-fold increase in potency relative to YSFKPMPLaR. These analyses showed that the peptides used in this study have up to 25% of the potency of C5a in human fetal artery and up to 5% of the activity of C5a in the PMN enzyme release assay.

Effects of dobutamine on gut mucosal nitric oxide production during endotoxic shock in rabbits

Background: Dobutamine is the agent of choice for increasing cardiac output during myocardial depression in humans with septic shock. Studies have shown that beta-adrenoceptor agonists influence nitric oxide generation, probably by modulating cyclic adenosine monophosphate. We investigated the effects of dobutamine on the systemic and luminal gut release of nitric oxide during endotoxic shock in rabbits. Materials/Methods: Twenty anesthetized and ventilated New Zealand rabbits received placebo or intravenous lipopolysaccharide with or without dobutamine (5 mu g/kg/min). Ultrasonic flow probes placed around the superior mesenteric artery and the abdominal aorta continously estimated the flow. A segment from the ileum was isolated and perfused, and scrum nitrate/nitrite levels were measured in the perfusate solution and the serum every hour. Results: The mean arterial pressure decreased with statistical significance in the lipopolysaccharide group but not in the lipopolysaccharide/dobutamine group. The abdominal aortic flow decreased statistically significantly after lipopolysaccharide administration in both groups but recovered to base-line in the lipopolysaccharide/dobutamine group. The flow in the superior mesenteric artery was statistically significantly higher in the lipopolysaccharide/dobutamine group than in the lipopolysaccharide group at 2 hours. The serum nitrate/nitrite levels were higher in the lipopolysaccharide group and lower in the lipopolysaccharide/dobutamine group than those in the control group. The gut luminal perfusate serum nitrate/nitric level was higher in the lipopolysaccharide group than in the lipopolysaccharide/dobutamine group. Conclusions: Dobutamine can decrease total and intestinal nitric oxide production in vivo. Those effects seem to be inversely proportional to the changes in blood flow.

Synthesis of fructans by partially purified fructosyltransferase activities from Lolium rigidum

Sucrose:sucrose fructosyltransferase (SST) activity was partially purified from whole shoots of Lolium rigidum by a combination of affinity chromatography, gel filtration and anion-exchange chromatography. The SST activity co-eluted with some fructan:fructan fructosyltransferase (FFT) and invertase activities and consequently the partially purified preparation was termed the fructosyltransferase (FT) preparation. The SST-like activity in the FT preparation was purified 214-fold and had an apparent molecular mass of 84 000. The FT preparation contained several peptides with an apparent pI of 4.6-4.7. When assayed with sucrose concentrations up to 600 mM, the FT preparation synthesized 1-kestose at all concentrations, and synthesized 6-kestose at concentrations of 150 mM and greater. The K-m of 1-kestose production was 0.2 M. When the FT preparation was assayed at a concentration of activity approximately half that measured in fresh tissue with 100 mM sucrose, 1-kestose, or 6(G)-kestose as substrates, fructans of degree of polymerization (DP) less than or equal to 5 were synthesized. A partially purified FFT activity, free of SST and invertase activities, which synthesized beta-2,1-glycosidic linked oligofructans of DP less than or equal to 6, was combined in vitro with the FT preparation (FFT-FT preparation) to give a ratio of SST:FFT activities similar to that measured in crude enzyme extracts from L. rigidum. The FFT-FT preparation synthesized oligofructans when assayed with 100 mM concentrations of sucrose, 1-kestose or 6(G)-kestose, but was not able to synthesize fructans of DP greater than or equal to 6 even after extended assays of up to 10 h. The FFT-FT preparation was also assayed with 100 mM sucrose with small amounts of concentrated sucrose added periodically during the assay to maintain the substrate concentration. In this assay, the FFT-FT preparation synthesized fructans up to an apparent DP of 17 or greater. The fructans of DP greater than or equal to 6 synthesized in the assay appeared to form two molecular series containing both beta-2,1- and beta-2,6-glycosidic linked fructosyl residues with terminal or internal glucosyl residues. The apparent rate of SST activity in the assay of the FFT-FT preparation was greater than that measured in a similar assay of the FT preparation alone which did not result in fructans with DP greater than or equal to 6. It was concluded that the FFT-FT preparation, when assayed with a continual supply of sucrose, contained a factor which promoted synthesis of fructans of DP greater than or equal to 6 and synthesis of beta-2,B-glycosidic linkages between fructosyl residues.

Oral budesonide is as effective as oral prednisolone in active Crohn's disease

Background-The use of corticosteroids in active Crohn's disease often becomes limited by side effects. Budesonide is a potent corticosteroid with low systemic bioavailability due to an extensive first pass liver metabolism. Aims-To compare the efficacy and safety of two dosage regimens of budesonide and prednisolone in patients with active Crohn's disease affecting the ileum and/or the ascending colon. Patients and methods-One hundred and seventy eight patients were randomised to receive budesonide controlled ileal release (CIR) capsules 9 mg once daily or 4.5 mg twice daily, or prednisolone tablets 40 mg once daily. The treatment period was 12 weeks. The primary efficacy variable was clinical remission, defined as a Crohn's Disease Activity Index (CDAI) of 150 or less. Results-After eight weeks of treatment, remission occurred in 60% of patients receiving budesonide once daily or prednisolone and in 42% of those receiving budesonide twice daily (p=0.062). The presence of glucocorticoid associated side effects was similar in all groups; however, moon face was more common in the prednisolone group (p=0.0005). The highest frequency of impaired adrenal function, as measured by a short ACTH test, was found in the prednisolone group (p=0.0023). Conclusions-Budesonide CIR, administered at 9 mg once daily or 4.5 mg twice daily, is comparable to prednisolone in inducing remission in active Crohn's disease. The single dose administration is as promptly effective as prednisolone and represents a simpler and safer therapeutic approach, with a considerable reduction in side effects.

International Society for Sexual Medicine`s Guidelines for the Diagnosis and Treatment of Premature Ejaculation

Introduction. Over the past 20 years our knowledge of premature ejaculation (PE) has significantly advanced. Specifically, we have witnessed substantial progress in understanding the physiology of ejaculation, clarifying the real prevalence of PE in population-based studies, reconceptualizing the definition and diagnostic criterion of the disorder, assessing the psychosocial impact on patients and partners, designing validated diagnostic and outcome measures, proposing new pharmacologic strategies and examining the efficacy, safety and satisfaction of these new and established therapies. Given the abundance of high level research it seemed like an opportune time for the International Society for Sexual Medicine (ISSM) to promulgate an evidenced-based, comprehensive and practical set of clinical guidelines for the diagnosis and treatment of PE. Aim. Develop clearly worded, practical, evidenced-based recommendations for the diagnosis and treatment of PE for family practice clinicians as well as sexual medicine experts. Method. Review of the literature. Results. This article contains the report of the ISSM PE Guidelines Committee. It affirms the ISSM definition of PE and suggests that the prevalence is considerably lower than previously thought. Evidence-based data regarding biological and psychological etiology of PE are presented, as is population-based statistics on normal ejaculatory latency. Brief assessment procedures are delineated and validated diagnostic and treatment questionnaires are reviewed. Finally, the best practices treatment recommendations are presented to guide clinicians, both familiar and unfamiliar with PE, in facilitating treatment of their patients. Conclusion. Development of guidelines is an evolutionary process that continually reviews data and incorporates the best new research. We expect that ongoing research will lead to a more complete understanding of the pathophysiology as well as new efficacious and safe treatments for this sexual dysfunction. Therefore, it is strongly recommended that these guidelines be re-evaluated and updated by the ISSM every 4 years. Althof SE, Abdo CHN, Dean J, Hackett G, McCabe M, McMahon CG, Rosen RC, Sadovsky R, Waldinger M, Becher E, Broderick GA, Buvat J, Goldstein I, El-Meliegy AI, Giuliano F, Hellstrom WJG, Incrocci L, Jannini EA, Park K, Parish S, Porst H, Rowland D, Segraves R, Sharlip I, Simonelli C, and Tan HM. International Society for Sexual Medicine`s guidelines for the diagnosis and treatment of premature ejaculation. J Sex Med 2010;7:2947-2969.

Protonectin (1-6): A novel chemotactic peptide from the venom of the social wasp Agelaia pallipes pallipes

Peptides constitute the largest group of Hymenoptera venom toxins; some of them interact with GPCR, being involved with the activation of different types of leukocytes, smooth muscle contraction and neurotoxicity. Most of these toxins vary from dodecapeptides to tetradecapeptides, amidated at their C-teminal amino acid residue. The venoms of social wasps can also contains some tetra-, penta-, hexa- and hepta-peptides, but just a few of them have been structurally and functionally characterized up to now. Protonectin (ILG-TILGLLKGL-NH(2)) is a polyfunctional peptide, presenting mast cell degranulation, release of lactate dehydrogenase (LDH) from mast cells, antibiosis against Gram-positive and Gram-negative bacteria and chemotaxis for polymorphonucleated leukocytes (PMNL), while Protonectin (1-6) (ILGTIL-NH(2)) only presents chemotaxis for PMNL However, the mixture of Protonectin (1-6) with Protonectin in the molar ratio of 1:1 seems to potentiate the biological activities dependent of the membrane perturbation caused by Protonectin, as observed in the increasing of the activities of mast cell degranulation, LDH releasing from mast cells, and antibiosis. Despite both peptides are able to induce PMNL chemotaxis, the mixture of them presents a reduced activity in comparison to the individual peptides. Apparently, when mixed both peptides seems to form a supra-molecular structure, which interact with the receptors responsible for PMNL chemotaxis, disturbing their individual docking with these receptors. In addition to this, a comparison of the sequences of both peptides suggests that the sequence ILGTIL is conserved, suggesting that it must constitute a linear motif for the structural recognition by the specific receptor which induces leukocytes migration. (C) 2010 Elsevier Ltd. All rights reserved.

Efficacy and Tolerability of Lodenafil Carbonate for Oral Therapy in Erectile Dysfunction: A Phase II Clinical Trial

Oral treatment with phosphodiesterase type 5 inhibitor (PDE5) is considered the first-line treatment for patients with erectile dysfunction (ED). Lodenafil carbonate (LC) is a novel PDE5. This is a phase II, prospective, randomized, double-blind, and placebo controlled clinical trial of LC. Efficacy end points were International Index of Sexual Function (IIEF) erectile domain, IIEF questions 3 and 4, and Sexual Encounter Profile (SEP) questions 2 and 3, before and after the use of LC or placebo. Seventy-two men older than 18 years, with ED for at least 6 months with stable sexual relationship were enrolled. Patients were randomized to placebo or LC 80 mg, 40 mg, or 20 mg and followed for 4 weeks. IIEF erectile domain scores before and after the use of medications were (mean +/- standard deviation [SD]): placebo: 11.9 +/- 3.4 and 12.6 +/- 5.5; LC 20 mg: 15.8 +/- 4.1 and 18.9 +/- 6.6; LC 40 mg: 11.9 +/- 4.4 and 15.4 +/- 8.1; LC 80 mg: 14.2 +/- 4.7 and 22.8 +/- 6.0 (anova P < 0.01). The SEP-2 scores before and after the use of medications were (Mean +/- SD): placebo: 71.0 +/- 33.1 and 51.2 +/- 43.1; LC 20 mg 70.3 +/- 34.2 and 75.5 +/- 31.5; LC 40 mg: 48.4 +/- 42.1 and 60.8 +/- 42.5; LC 80 mg: 68.6 +/- 33.5 and 89.6 +/- 26.0. The SEP-3 scores were: placebo 23.3 +/- 27.6 and 33.6 +/- 42.3; LC 20 mg: 32.3 +/- 38.9 and 51.2 +/- 41.7; LC 40 mg: 39.7 +/- 44.7 and 46.7 +/- 41.1; LC 80 mg* 17.2 +/- 29.5 and 74.3 +/- 36.4 (*P < 0.05 for difference to placebo). The drug was well tolerated. Adverse reactions were mild and self-limited and included headache, rhinitis, flushing, color visual disorders, and dyspepsia. This study showed that the dosage of 80 mg of LC was significantly more efficacious than placebo and well tolerated. Glina S, Toscano I, Gomatzky C, de Goes PM, Junior AN, de Almeida Claro JF, and Pagani E. Efficacy and tolerability of lodenafil carbonate for oral therapy in erectile dysfunction: A phase II clinical trial. J Sex Med 2009;6:553-557.

Pediatric Antiphospholipid Syndrome: Clinical and Immunologic Features of 121 Patients in an International Registry

OBJECTIVES. The purpose of this study was to obtain data on the association of antiphospholipid antibodies with clinical manifestations in childhood and to enable future studies to determine the impact of treatment and long-term outcome of pediatric antiphospholipid syndrome. PATIENTS AND METHODS. A European registry extended internationally of pediatric patients with antiphospholipid syndrome was established as a collaborative project of the European Antiphospholipid Antibodies Forum and Lupus Working Group of the Pediatric Rheumatology European Society. To be eligible for enrollment the patient must meet the preliminary criteria for the classification of pediatric antiphospholipid syndrome and the onset of antiphospholipid syndrome must have occurred before the patient`s 18th birthday. RESULTS. As of December 1, 2007, there were 121 confirmed antiphospholipid syndrome cases registered from 14 countries. Fifty-six patients were male, and 65 were female, with a mean age at the onset of antiphospholipid syndrome of 10.7 years. Sixty (49.5%) patients had underlying autoimmune disease. Venous thrombosis occurred in 72 (60%), arterial thrombosis in 39 (32%), small-vessel thrombosis in 7 (6%), and mixed arterial and venous thrombosis in 3 (2%). Associated nonthrombotic clinical manifestations included hematologic manifestations (38%), skin disorders (18%), and nonthrombotic neurologic manifestations (16%). Laboratory investigations revealed positive anticardiolipin antibodies in 81% of the patients, anti-beta(2)-glycoprotein I antibodies in 67%, and lupus anticoagulant in 72%. Comparisons between different subgroups revealed that patients with primary antiphospholipid syndrome were younger and had a higher frequency of arterial thrombotic events, whereas patients with antiphospholipid syndrome associated with underlying autoimmune disease were older and had a higher frequency of venous thrombotic events associated with hematologic and skin manifestations. CONCLUSIONS. Clinical and laboratory characterization of patients with pediatric antiphospholipid syndrome implies some important differences between antiphospholipid syndrome in pediatric and adult populations. Comparisons between children with primary antiphospholipid syndrome and antiphospholipid syndrome associated with autoimmune disease have revealed certain differences that suggest 2 distinct subgroups. Pediatrics 2008; 122: e1100-e1107