A study protocol for risk stratification in children with concussion (RSiCC): Theoretical framework, design, and methods.

Research shows that one in five children will experience a concussion by age 16. Compared to adults, children experience longer and more severe postconcussive symptoms (PCS), with severity and duration varying considerably among children and complicating management of these patients. Persistent PCS can result in increased school absenteeism, social isolation, and psychological distress. Although early PCS diagnosis and access to evidence-based interventions are strongly linked to positive health and academic outcomes, symptom severity and duration are not fully explained by acute post-injury symptoms. Prior research has focused on the role of neuroinflammation in mediating PCS and associated fatigue; however relationship between inflammatory biomarkers and PCS severity, has not examined longitudinally. To identify which children are at high risk for persistent PCS and poor health, academic, and social outcomes, research tracking PCS trajectories and describing school-based impacts across the entire first year postinjury is critically needed. This study will 1) define novel PCS trajectory typologies in a racially/ethnically diverse population of 500 children with concussion (11-17 years, near equal distribution by sex), 2) identify associations between these typologies and patterns of inflammatory biomarkers and genetic variants, 3) develop a risk stratification model to identify children at risk for persistent PCS; and 4) gain unique insights and describe PCS impact, including fatigue, on longer-term academic and social outcomes. We will be the first to use NIH's symptom science model and patient-reported outcomes to explore the patterns of fatigue and other physical, cognitive, psychological, emotional and academic responses to concussion in children over a full year. Our model will enable clinicians and educators to identify children most at risk for poor long-term health, social, and academic outcomes after concussion. This work is critical to meeting our long-term goal of developing personalized concussion symptom-management strategies to improve outcomes and reduce disparities in the health and quality of life of children.

Moving towards a cure: blocking pathogenic antibodies in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is characterized by the presence of autoantibodies that can mediate tissue damage in multiple organs. The underlying aetiology of SLE autoantibodies remains unknown, and treatments aimed at eliminating B cells, or limiting their function, have demonstrated limited therapeutic benefit. Thus, the current therapies for SLE are based on the concept of nonspecific immunosuppression and consist of nonsteroidal anti-inflammatory drugs (NSAIDS), corticosteroids, anti-malarials and cytotoxic drugs, all of which have serious adverse side effects including organ damage. The major auto-specificity in SLE is double-stranded (ds) DNA. Many anti-dsDNA antibodies cross-react with non-DNA antigens that may be the direct targets for their pathogenic activity. Studying anti-dsDNA antibodies present in SLE patients and in animal models of lupus, we have identified a subset of anti-dsDNA antibodies which is pathogenic in the brain as well as in the kidney. We have recently demonstrated that specific peptides, or small molecules, can protect target organs from antibody-mediated damage. Thus, it might be possible to treat the aspects of autoimmune disease without inducing major immunosuppression and ensuing infectious complications.

Prevalence of Inflammatory Heart Disease Among Professional Athletes With Prior COVID-19 Infection Who Received Systematic Return-to-Play Cardiac Screening.

Importance: The major North American professional sports leagues were among the first to return to full-scale sport activity during the coronavirus disease 2019 (COVID-19) pandemic. Given the unknown incidence of adverse cardiac sequelae after COVID-19 infection in athletes, these leagues implemented a conservative return-to-play (RTP) cardiac testing program aligned with American College of Cardiology recommendations for all athletes testing positive for COVID-19. Objective: To assess the prevalence of detectable inflammatory heart disease in professional athletes with prior COVID-19 infection, using current RTP screening recommendations. Design, Setting, and Participants: This cross-sectional study reviewed RTP cardiac testing performed between May and October 2020 on professional athletes who had tested positive for COVID-19. The professional sports leagues (Major League Soccer, Major League Baseball, National Hockey League, National Football League, and the men's and women's National Basketball Association) implemented mandatory cardiac screening requirements for all players who had tested positive for COVID-19 prior to resumption of team-organized sports activities. Exposures: Troponin testing, electrocardiography (ECG), and resting echocardiography were performed after a positive COVID-19 test result. Interleague, deidentified cardiac data were pooled for collective analysis. Those with abnormal screening test results were referred for additional testing, including cardiac magnetic resonance imaging and/or stress echocardiography. Main Outcomes and Measures: The prevalence of abnormal RTP test results potentially representing COVID-19-associated cardiac injury, and results and outcomes of additional testing generated by the initial screening process. Results: The study included 789 professional athletes (mean [SD] age, 25 [3] years; 777 men [98.5%]). A total of 460 athletes (58.3%) had prior symptomatic COVID-19 illness, and 329 (41.7%) were asymptomatic or paucisymptomatic (minimally symptomatic). Testing was performed a mean (SD) of 19 (17) days (range, 3-156 days) after a positive test result. Abnormal screening results were identified in 30 athletes (3.8%; troponin, 6 athletes [0.8%]; ECG, 10 athletes [1.3%]; echocardiography, 20 athletes [2.5%]), necessitating additional testing; 5 athletes (0.6%) ultimately had cardiac magnetic resonance imaging findings suggesting inflammatory heart disease (myocarditis, 3; pericarditis, 2) that resulted in restriction from play. No adverse cardiac events occurred in athletes who underwent cardiac screening and resumed professional sport participation. Conclusions and Relevance: This study provides large-scale data assessing the prevalence of relevant COVID-19-associated cardiac pathology with implementation of current RTP screening recommendations. While long-term follow-up is ongoing, few cases of inflammatory heart disease have been detected, and a safe return to professional sports activity has thus far been achieved.

Suppression of proinflammatory cytokines in monocytes by a tetravalent guanylhydrazone.

An overproduction of proinflammatory cytokines by activated macrophages/monocytes mediates the injurious sequelae of inflammation, septic shock, tissue injury, and cachexia. We recently synthesized a tetravalent guanylhydrazone compound (CNI-1493) that inhibits cytokine-inducible arginine transport and nitric oxide (NO) production in macrophages, and protects mice against lethal endotoxemia and carrageenan-induced inflammation. During these investigations we noticed that CNI-1493 effectively prevented lipopolysaccharide (LPS)-induced NO production, even when added in concentrations 10-fold less than required to competitively inhibit L-arginine uptake, suggesting that the suppressive effects of this guanylhydrazone compound might extend to other LPS-induced responses. Here, we report that CNI-1493 suppressed the LPS-stimulated production of proinflammatory cytokines (tumor necrosis factor [TNF], interleukins 1beta and 6, macrophage inflammatory proteins 1alpha and 1beta) from human peripheral blood mononuclear cells. Cytokine suppression was specific, in that CNI-1493 did not inhibit either the constitutive synthesis of transforming growth factor beta or the upregulation of major histocompatibility complex class II by interferon gamma (IFN-gamma). In contrast to the macrophage suppressive actions of dexamethasone, which are overridden in the presence of IFN-gamma, CNI-1493 retained its suppressive effects even in the presence of IFN-gamma. The mechanism of cytokine-suppressive action by CNI-1493 was independent of extracellular L-arginine content and NO production and is not restricted to induction by LPS. As a selective inhibitor of macrophage activation that prevents TNF production, this tetravalent guanylhydrazone could be useful in the development of cytokine-suppressive agents for the treatment of diseases mediated by overproduction of cytokines.

High mobility group 1 protein (HMG-1) stimulates proinflammatory cytokine synthesis in human monocytes.

Lipopolysaccharide (LPS) is lethal to animals because it activates cytokine release, causing septic shock and tissue injury. Early proinflammatory cytokines (e.g., tumor necrosis factor [TNF] and interleukin [IL]-1) released within the first few hours of endotoxemia stimulate mediator cascades that persist for days and can lead to death. High mobility group 1 protein (HMG-1), a ubiquitous DNA-binding protein, was recently identified as a "late" mediator of endotoxin lethality. Anti-HMG-1 antibodies neutralized the delayed increase in serum HMG-1, and protected against endotoxin lethality, even when passive immunization was delayed until after the early cytokine response. Here we examined whether HMG-1 might stimulate cytokine synthesis in human peripheral blood mononuclear cell cultures. Addition of purified recombinant HMG-1 to human monocyte cultures significantly stimulated the release of TNF, IL-1alpha, IL-1beta, IL-1RA, IL-6, IL-8, macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta; but not IL-10 or IL-12. HMG-1 concentrations that activated monocytes were within the pathological range previously observed in endotoxemic animals, and in serum obtained from septic patients. HMG-1 failed to stimulate cytokine release in lymphocytes, indicating that cellular stimulation was specific. Cytokine release after HMG-1 stimulation was delayed and biphasic compared with LPS stimulation. Computer-assisted image analysis demonstrated that peak intensity of HMG-1-induced cellular TNF staining was comparable to that observed after maximal stimulation with LPS. Administration of HMG-1 to Balb/c mice significantly increased serum TNF levels in vivo. Together, these results indicate that, like other cytokine mediators of endotoxin lethality (e.g., TNF and IL-1), extracellular HMG-1 is a regulator of monocyte proinflammatory cytokine synthesis.

Poorly differentiated cutaneous squamous cell carcinomas have high incomplete excision rates with UK minimum recommended pre-determined surgical margins.

BACKGROUND: In the UK, the British Association of Dermatology-British Association of Plastic, Reconstructive and Aesthetic Surgery (BAD-BAPRAS) guidelines recommend excision of high-risk cutaneous squamous cell carcinomas (cSCCs), including poorly differentiated cSCCs, with a minimum peripheral margin of 6 mm1. OBJECTIVES: We assess whether the BAD-BAPRAS minimum margin achieves histological clearance in poorly differentiated cSCCs. PATIENTS AND METHODS: Demographics, surgical notes and histological reports from all patients having a primary cSCC excised at the Plastic Surgery Department of Addenbrooke's Hospital, Cambridge, UK, between January 2017 and April 2018 were analysed. Ordinal regression was performed for excision margin status versus histological grade by using size and site as co-variates. RESULTS: Of 296 cSCCs, 38(12.8%) were poorly differentiated. Patients with poorly differentiated cSCCs were older (81.1 years vs. 76.7 years, p = 0.038), had lesions on the face or scalp (89.2% vs. 52.1%, p = 0.0001), and had lymphovascular (10.5% vs. 0%, p = 0.001) or perineural invasion (15.8% vs. 2%, p = 0.002). Well-differentiated cSCCs were excised with an average peripheral margin of 4.72 mm (95% CI 4.25-5.18 mm), while poorly differentiated cSCCs were excised with a margin of 6.42 mm(95% CI 5.58-7.28 mm). Close or involved peripheral margins were seen in 3% of well-differentiated lesions but in 13.2% of poorly differentiated lesions (OR=45.02; p = 0.003). Deep margins were close in 13.1% (none involved) of well-differentiated lesions but close or involved in 50% of poorly differentiated lesions (OR=11.94; p = 0.001). CONCLUSIONS: We demonstrate that poorly differentiated cSCCs are frequently incompletely excised in both peripheral and deep planes, despite adherence to guidelines. The UK BAD-BAPRAS guidelines should be urgently updated in line with international consensus.

Concussion Guidelines Step 2: Evidence for Subtype Classification.

BACKGROUND: Concussion is a heterogeneous mild traumatic brain injury (mTBI) characterized by a variety of symptoms, clinical presentations, and recovery trajectories. By thematically classifying the most common concussive clinical presentations into concussion subtypes (cognitive, ocular-motor, headache/migraine, vestibular, and anxiety/mood) and associated conditions (cervical strain and sleep disturbance), we derive useful definitions amenable to future targeted treatments. OBJECTIVE: To use evidence-based methodology to characterize the 5 concussion subtypes and 2 associated conditions and report their prevalence in acute concussion patients as compared to baseline or controls within 3 d of injury. METHODS: A multidisciplinary expert workgroup was established to define the most common concussion subtypes and their associated conditions and select clinical questions related to prevalence and recovery. A literature search was conducted from January 1, 1990 to November 1, 2017. Two experts abstracted study characteristics and results independently for each article selected for inclusion. A third expert adjudicated disagreements. Separate meta-analyses were conducted to do the following: 1) examine the prevalence of each subtype/associated condition in concussion patients using a proportion, 2) assess subtype/associated conditions in concussion compared to baseline/uninjured controls using a prevalence ratio, and 3) compare the differences in symptom scores between concussion subtypes and uninjured/baseline controls using a standardized mean difference (SMD). RESULTS: The most prevalent concussion subtypes for pediatric and adult populations were headache/migraine (0.52; 95% CI = 0.37, 0.67) and cognitive (0.40; 95% CI = 0.25, 0.55), respectively. In pediatric patients, the prevalence of the vestibular subtype was also high (0.50; 95% CI = 0.40, 0.60). Adult patients were 4.4, 2.9, and 1.7 times more likely to demonstrate cognitive, vestibular, and anxiety/mood subtypes, respectively, as compared with their controls (P < .05). Children and adults with concussion showed significantly more cognitive symptoms than their respective controls (SMD = 0.66 and 0.24; P < .001). Furthermore, ocular-motor in adult patients (SMD = 0.72; P < .001) and vestibular symptoms in both pediatric and adult patients (SMD = 0.18 and 0.36; P < .05) were significantly worse in concussion patients than in controls. CONCLUSION: Five concussion subtypes with varying prevalence within 3 d following injury are commonly seen clinically and identifiable upon systematic literature review. Sleep disturbance, a concussion-associated condition, is also common. There was insufficient information available for analysis of cervical strain. A comprehensive acute concussion assessment defines and characterizes the injury and, therefore, should incorporate evaluations of all 5 subtypes and associated conditions.

HMG-1 as a late mediator of endotoxin lethality in mice.

Endotoxin, a constituent of Gram-negative bacteria, stimulates macrophages to release large quantities of tumor necrosis factor (TNF) and interleukin-1 (IL-1), which can precipitate tissue injury and lethal shock (endotoxemia). Antagonists of TNF and IL-1 have shown limited efficacy in clinical trials, possibly because these cytokines are early mediators in pathogenesis. Here a potential late mediator of lethality is identified and characterized in a mouse model. High mobility group-1 (HMG-1) protein was found to be released by cultured macrophages more than 8 hours after stimulation with endotoxin, TNF, or IL-1. Mice showed increased serum levels of HMG-1 from 8 to 32 hours after endotoxin exposure. Delayed administration of antibodies to HMG-1 attenuated endotoxin lethality in mice, and administration of HMG-1 itself was lethal. Septic patients who succumbed to infection had increased serum HMG-1 levels, suggesting that this protein warrants investigation as a therapeutic target.

Representation of concussion subtypes in common postconcussion symptom-rating scales.

AIM: Postconcussion symptom-rating scales are frequently used concussion assessment tools that do not align directly with new expert, consensus-based concussion subtype classification systems. This may result in delays in concussion diagnosis, subspecialty referral and rehabilitative strategies. OBJECTIVE: To determine the representation of subtype-directed symptomatology in common postconcussion symptom-rating scales. METHODS: Literature review and expert consensus were used to compile commonly used concussion symptom-rating scales. Statistics were generated to describe the degree of representation of the consensus symptom set. RESULTS: The percentage of symptoms representing each subtype/associated condition is low overall (15-26%). The ocular-motor (11%) and vestibular subtypes (19%) and cervical strain (5%)-associated condition were the most under-represented and also had the greatest unmet needs. CONCLUSION: Concussion subtypes do not have equal representation on commonly used concussion symptom-rating scales. There is a need for a subtype-directed symptom assessment to allow for increased accuracy of diagnosis and to guide management.

Statements of Agreement From the Targeted Evaluation and Active Management (TEAM) Approaches to Treating Concussion Meeting Held in Pittsburgh, October 15-16, 2015.

BACKGROUND: Conventional management for concussion involves prescribed rest and progressive return to activity. Recent evidence challenges this notion and suggests that active approaches may be effective for some patients. Previous concussion consensus statements provide limited guidance regarding active treatment. OBJECTIVE: To describe the current landscape of treatment for concussion and to provide summary agreements related to treatment to assist clinicians in the treatment of concussion. METHODS: On October 14 to 16, 2015, the Targeted Evaluation and Active Management (TEAM) Approaches to Treating Concussion meeting was convened in Pittsburgh, Pennsylvania. Thirty-seven concussion experts from neuropsychology, neurology, neurosurgery, sports medicine, physical medicine and rehabilitation, physical therapy, athletic training, and research and 12 individuals representing sport, military, and public health organizations attended the meeting. The 37 experts indicated their agreement on a series of statements using an audience response system clicker device. RESULTS: A total of 16 statements of agreement were supported covering (1) Summary of the Current Approach to Treating Concussion, (2) Heterogeneity and Evolving Clinical Profiles of Concussion, (3) TEAM Approach to Concussion Treatment: Specific Strategies, and (4) Future Directions: A Call to Research. Support (ie, response of agree or somewhat agree) for the statements ranged from to 97% to 100%. CONCLUSION: Concussions are characterized by diverse symptoms and impairments and evolving clinical profiles; recovery varies on the basis of modifying factors, injury severity, and treatments. Active and targeted treatments may enhance recovery after concussion. Research is needed on concussion clinical profiles, biomarkers, and the effectiveness and timing of treatments. ABBREVIATIONS: ARS, audience response systemCDC, Centers for Disease Control and PreventionDoD, Department of DefensemTBI, mild traumatic brain injuryNCAA, National Collegiate Athletic AssociationNFL, National Football LeagueNIH, National Institutes of HealthRCT, randomized controlled trialRTP, return to playSRC, sport- and recreation-related concussionTBI, traumatic brain injuryTEAM, Targeted Evaluation and Active Management.

Basic biomechanics of the lower extremity.

This article describes common principles of biomechanics for running, jumping, and kicking. These activities form the basis for much of sports activity. Understanding human movement allows the physician to prescribe appropriate prevention, treatment, and rehabilitation to patients.

Hypophysectomy, high tumor necrosis factor levels, and hemoglobinemia in lethal endotoxemic shock.

Experimental models of lethal endotoxemia in rodents are widely used to delineate pathogenic mechanisms of inflammation, sepsis, and septic shock. One long-standing but poorly understood observation is that removal of the pituitary gland (hypophysectomy) renders experimental animals 1,000-fold more sensitive to the lethal sequelae of lipopolysaccharide (LPS). Previous explanations for this phenomenon focused on hypophysectomy-induced deficiencies of corticosteroids, because glucocorticoids effectively suppress the synthesis of tumor necrosis factor (TNF), which is a primary mediator of LPS lethality. We measured LPS-stimulated macrophage TNF release in the presence of serum from hypophysectomized rats to detect the appearance of an inducible 65 kDa protein that enhances TNF release. Surprisingly, the N-terminal amino acid sequence analysis of the isolated, purified protein revealed its identity as hemoglobin. Hypophysectomy significantly increases serum hemoglobin levels (control hemoglobin = 103+/-18 microg/mL versus hypophysectomized serum hemoglobin = 279+/-13 microg/mL; p < .05). Purified hemoglobin enhances TNF synthesis in LPS-stimulated macrophages by at least 1,000-fold, which is specifically inhibited by antihemoglobin antibodies. Thus, hemoglobin mediates increased TNF synthesis in endotoxemic, hypophysectomized rats. This mechanism of increased TNF release has potential implications for patients with hemoglobinemia following blood transfusion, surgery, injury, infection, or other conditions that can be associated with endotoxemia and sepsis.

Tumor necrosis factor is a brain damaging cytokine in cerebral ischemia.

Two contrasting roles, one beneficial and the injurious, have been proposed for tumor necrosis factor (TNF) in the pathogenesis of cerebral ischemia. Reported here are results obtained in a standard model of permanent focal cortical ischemia in rats, in which the volume of cerebral infarction is measured after permanent occlusion of the middle cerebral artery. Administration of neutralizing anti-rat TNF antibodies (P114) into the brain cortex significantly reduced ischemic brain damage (85% reduced infarct volume as compared with preimmune-treated controls). Similar results were achieved by systemic administration of CNI-1493, a recently described tetravalent guanylhydrazone compound, which effectively inhibited endogenous brain TNF synthesis and conferred significant protection against the development of cerebral infarction (80% reduced infarct volume as compared with vehicle controls treated 1 h postischemia with 10 mg/kg). P114 anti-TNF and CNI-1493 were each cerebroprotective when given within a clinically relevant time window for up to 2 h after the onset of ischemia. These findings establish an important, pathophysiological role of TNF in mediating the progression of ischemic brain damage, and suggest that inhibiting TNF with CNI-1493 may be beneficial in the future treatment of stroke.

Proinflammatory cytokines (tumor necrosis factor and interleukin 1) stimulate release of high mobility group protein-1 by pituicytes.

BACKGROUND: Cytokines mediate the metabolic and physiologic responses to injury and infection. Anterior pituitary cells express receptors for tumor necrosis factor (TNF) and interleukin 1 (IL-1), which can signal these cells to release corticotropin, growth hormone, and cytokines such as IL-1 and macrophage migration inhibitory factor. This interaction provides an important link between the immune system and the neuroendocrine system. We reasoned that pituicytes activated with TNF or IL-1 might release previously unrecognized factors that could participate in this signaling from the neuroendocrine to the immune system. METHODS: Proteins released from rat pituicytes (GH3) after stimulation with proinflammatory cytokines were identified by N-terminal amino acid sequencing. Polyclonal antibodies against a peptide corresponding to the N-terminal amino acid sequence were generated and used to determine the kinetics of protein release. RESULTS: Cytokine stimulation induced the release of a 30-kd protein from rat pituicytes. After the protein was isolated and the N-terminal amino acid sequence determined, a protein database analysis revealed that it is high mobility group-1 (HMG-1) protein. TNF and IL-1 induced the release of HMG-1 from pituicytes in a time- and dose-dependent manner. Interferon gamma alone did not induce the release of HMG-1, but it enhanced TNF-induced HMG-1 release. CONCLUSION: Stimulation of pituicytes by TNF or IL-1 induces the release of HMG-1, which may participate in the regulation of neuroendocrine and immune responses to infection or injury.

Cerebroprotective effects of aminoguanidine in a rodent model of stroke.

BACKGROUND AND PURPOSE: During a cerebral infarction, a complex cascade of cytotoxic events ultimately determines the volume of brain cell loss. The studies presented here demonstrate that aminoguanidine, an experimental therapeutic currently in clinical trials to prevent diabetic complications, is cerebroprotective in focal cerebral infarction. METHODS: Adult Lewis rats (n = 6 to 12 per group) were anesthetized with ketamine and subjected to focal cerebral infarction by tandem permanent occlusion of the right middle cerebral artery and ipsilateral common carotid artery (CCA), followed by temporary occlusion of the contralateral CCA. Infarct volume (cortical) was assessed 24 hours after the onset of ischemia by planimetric analysis of coronal brain slices stained with tetrazolium. RESULTS: Aminoguanidine (320 mg/kg IP) administered 15 minutes after the onset of ischemia resulted in a significant reduction of infarct volume (7.6 +/- 2.6% of hemisphere in controls versus 1.3 +/- 0.2% of hemisphere in aminoguanidine-treated rats; P < .05). Administration of aminoguanidine conferred significant cerebroprotection even when administered 1 or 2 hours after the onset of ischemia (88% and 85% reduction from control, respectively; P < .05). Cerebroprotection by aminoguanidine was independent of systemic physiological variables known to influence stroke size (eg, temperature, mean arterial blood pressure, blood glucose, and arterial pH, PCO2, and PO2). CONCLUSIONS: These results indicate that the stroke-reducing properties of aminoguanidine are dose and time dependent, with substantial cerebroprotection persisting even with drug delivery up to 2 hours after the onset of ischemia. It is now plausible to pursue development of aminoguanidine as an experimental therapeutic in stroke, and possible mechanisms of these cerebroprotective effects are under consideration.

An inhibitor of macrophage arginine transport and nitric oxide production (CNI-1493) prevents acute inflammation and endotoxin lethality.

BACKGROUND: Nitric oxide (NO), a small effector molecule produced enzymatically from L-arginine by nitric oxide synthase (NOS), is a mediator not only of important homeostatic mechanisms (e.g., blood vessel tone and tissue perfusion), but also of key aspects of local and systemic inflammatory responses. Previous efforts to develop inhibitors of NOS to protect against NO-mediated tissue damage in endotoxin shock have been unsuccessful, largely because such competitive NOS antagonists interfere with critical vasoregulatory NO production in blood vessels and decrease survival in endotoxemic animals. Accordingly, we sought to develop a pharmaceutical approach to selectively inhibit NO production in macrophages while sparing NO responses in blood vessels. MATERIALS AND METHODS: The process of cytokine-inducible L-arginine transport and NO production were studied in the murine macrophage-like cell line (RAW 264.7). A series of multivalent guanylhydrazones were synthesized to inhibit cytokine-inducible L-arginine transport. One such compound (CNI-1493) was studied further in animal models of endothelial-derived relaxing factor (EDRF) activity, carrageenan inflammation, and lethal lipopolysaccharide (LPS) challenge. RESULTS: Upon activation with cytokines, macrophages increase transport of L-arginine to support the production of NO by NOS. Since endothelial cells do not require this additional arginine transport to produce NO, we reasoned that a competitive inhibitor of cytokine-inducible L-arginine transport would not inhibit EDRF activity in blood vessels, and thus might be effectively employed against endotoxic shock. CNI-1493, a tetravalent guanylhydrazone, proved to be a selective inhibitor of cytokine-inducible arginine transport and NO production, but did not inhibit EDRF activity. In mice, CNI-1493 prevented the development of carrageenan-induced footpad inflammation, and conferred protection against lethal LPS challenge. CONCLUSIONS: A selective inhibitor of cytokine-inducible L-arginine transport that does not inhibit vascular EDRF responses is effective against endotoxin lethality and significantly reduces inflammatory responses.

Neurotoxicity of advanced glycation endproducts during focal stroke and neuroprotective effects of aminoguanidine.

Cerebral infarction (stroke) is a potentially disastrous complication of diabetes mellitus, principally because the extent of cortical loss is greater in diabetic patients than in nondiabetic patients. The etiology of this enhanced neurotoxicity is poorly understood. We hypothesized that advanced glycation endproducts (AGEs), which have previously been implicated in the development of other diabetic complications, might contribute to neurotoxicity and brain damage during ischemic stroke. Using a rat model of focal cerebral ischemia, we show that systemically administered AGE-modified bovine serum albumin (AGE-BSA) significantly increased cerebral infarct size. The neurotoxic effects of AGE-BSA administration were dose- and time-related and associated with a paradoxical increase in cerebral blood flow. Aminoguanidine, an inhibitor of AGE cross-linking, attenuated infarct volume in AGE-treated animals. We conclude that AGEs may contribute to the increased severity of stroke associated with diabetes and other conditions characterized by AGE accumulation.