C1 inhibitor serpin domain structure reveals the likely mechanism of heparin potentiation and conformational disease.
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C1 inhibitor, a member of the serpin family, is a major down-regulator of inflammatory processes in blood. Genetic deficiency of C1 inhibitor results in hereditary angioedema, a dominantly inheritable, potentially lethal disease. Here we report the first crystal structure of the serpin domain of human C1 inhibitor, representing a previously unreported latent form, which explains functional consequences of several naturally occurring mutations, two of which are discussed in detail. The presented structure displays a novel conformation with a seven-stranded beta-sheet A. The unique conformation of the C-terminal six residues suggests its potential role as a barrier in the active-latent transition. On the basis of surface charge pattern, heparin affinity measurements, and docking of a heparin disaccharide, a heparin binding site is proposed in the contact area of the serpin-proteinase encounter complex. We show how polyanions change the activity of the C1 inhibitor by a novel "sandwich" mechanism, explaining earlier reaction kinetic and mutagenesis studies. These results may help to improve therapeutic C1 inhibitor preparations used in the treatment of hereditary angioedema, organ transplant rejection, and heart attack. (+info)
Methylene blue for clinical anaphylaxis treatment: a case report.
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CONTEXT AND OBJECTIVE: Nitric oxide has a pathophysiological role in modulating systemic changes associated with anaphylaxis. Nitric oxide synthase inhibitors may exacerbate bronchospasm in anaphylaxis and worsen clinical conditions, with limited roles in anaphylactic shock treatment. The aim here was to report an anaphylaxis case (not anaphylactic shock), reversed by methylene blue (MB), a guanylyl cyclase inhibitor. CASE REPORT: A 23-year-old female suddenly presented urticaria and pruritus, initially on her face and arms, then over her whole body. Oral antihistamine was administered initially, but without improvement in symptoms and signs until intravenous methylprednisolone 500 mg. Recurrence occurred after two hours, plus vomiting. Associated upper respiratory distress, pulmonary sibilance, laryngeal stridor and facial angioedema (including erythema and lip edema) marked the evolution. At sites with severe pruritus, petechial lesions were observed. The clinical situation worsened, with dyspnea, tachypnea, peroral cyanosis, laryngeal edema with severe expiratory dyspnea and deepening unconsciousness. Conventional treatment was ineffective. Intubation and ventilatory support were then considered, because of severe hypoventilation. But, before doing that, based on our previous experience, 1.5 mg/kg (120 mg) bolus of 4% MB was infused, followed by one hour of continuous infusion of another 120 mg diluted in dextrose 5% in water. Following the initial intravenous MB dose, the clinical situation reversed completely in less than 20 minutes, thereby avoiding tracheal intubation. CONCLUSION: Although the nitric oxide hypothesis for MB effectiveness discussed here remains unproven, our intention was to share our accumulated cohort experience, which strongly suggests MB is a lifesaving treatment for anaphylactic shock and/or anaphylaxis and other vasoplegic conditions. (+info)
Falsely normal C4 in a case of acquired C1 esterase inhibitor deficiency.
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A 59-year-old lady presented with recurrent angioedema without urticaria. The clinical history and examination were consistent with an acquired C1 esterase deficiency secondary to lymphoproliferative disease. Despite a low C1 esterase level, the C4 level assayed by nephelometry on our automated analyser was normal. Analysis using different nephelometric analysers revealed consistently low C4, despite consistent normal readings in our analyser. Further investigation revealed an IgM-kappa paraprotein that seemed to interfere with both this and haematology coagulation assays. Splenic marginal zone lymphoma was confirmed on bone marrow biopsy. Monoclonal paraproteins may interfere with nephelometric, turbidimetric and immunological assays in a non-antibody-specific manner and should be considered when there are unusual or unexpected results, particularly in a patient with lymphoproliferative disease. (+info)
A case of angioedema associated with decreased C1 inhibitor activity.
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BACKGROUND: We report a case of a 31-year-old woman who began to notice swelling of her arms at age 20. She was once given a diagnosis of cellulitis, but her symptoms spontaneously resolved. The patient had swelling of the left forearm and palm and was referred to our department for evaluation. She had slight pain but no obvious weight gain. CASE SUMMARY: Antinuclear antibody and other autoantibodies, including anti-ds-DNA antibody, anti-RNP antibody, anti-Sm antibody, and anti-SS-A antibody were not detected. C1 inhibitor activity was low, C3 was normal, C4 was low, CH(50) was low, and C1q was normal. DISCUSSION: Based on the presence of the typical clinical features and the positive results on the complement tests, we diagnosed hereditary angioedema. A decrease in C1 inhibitor activity and an increase in specific protein concentrations indicated type 1. (+info)
Challenge-based clinical patterns of 223 Spanish patients with nonsteroidal anti-inflammatory-drug-induced-reactions.
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BACKGROUND: The single-blind, placebo controlled oral challenge (SBPCOC) is the definitive way to diagnosis nonsteroidal anti-inflammatory drug (NSAID)-induced reactions. OBJECTIVE: To evaluate 223 NSAID-sensitive patients by means of SBPCOC, and to describe the main clinical patterns found. METHODS: A prospective study was carried out, including 2 patient groups with case histories consistent with NSAID-induced reactions. Of the 223 patients, 174 were diagnosed on the basis of a positive SBPCOC. The second group consisted of 49 patients who were referred because of a documented history of anaphylaxis after taking NSAIDs, and these underwent SBPCOC with potent cyclooxygenase (COX)-1/COX-2 inhibitors, except those reported as being responsible for the reaction. The type of SBPCOC reaction, the NSAID reactivity pattern, and the associated diseases were the main classification criteria. RESULTS: Two broad categories of NSAID-induced reactions were identified: the cross-reactive and selective syndromes. The 150 patients who showed cross-reactive syndromes included 3 types of diseases: type 1, patients with rhinitis and/or asthma who developed nasoocular and/or asthmatic reactions (n=40); type 2, patients with or without chronic urticaria who presented urticaria/angioedema (n=59); and type 3, atopic patients with isolated periorbital angioedema (n=51). In contrast, the selective syndromes, or type 4, included 50 patients who developed anaphylaxis, as well as 11 patients with urticaria during SBPCOC. Finally, a miscellaneous group of reactions not matching any of the above types was identified (n=1 2). CONCLUSIONS: NSAID-sensitive patients can be classified into 4 different groups of reactors, each with well-defined clinical characteristics. Thus, a clinical classification of this NSAID-induced reaction complex is proposed. (+info)
An evaluation of tests used for the diagnosis and monitoring of C1 inhibitor deficiency: normal serum C4 does not exclude hereditary angio-oedema.
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Reduced levels of serum C4 have been considered a ubiquitous finding in hereditary angio-oedema (HAE), and consequently low C4 is often used to 'request manage' access to C1 inhibitor assays in the United Kingdom. However, in our experience normal C4 may occasionally be compatible with HAE. We audited the results of serum C4, C1 inhibitor antigen (C1inhA) and C1 inhibitor function (C1inhF) in 49 HAE patients, compared to a control group of 58 unaffected subjects. The sensitivity of low serum C4 for HAE among untreated patients was 81%; levels of complement C4 were within the normal range on nine separate occasions in five untreated HAE patients. Molecular genetic analysis of these individuals demonstrated novel mutations in the C1 inhibitor gene. The supplied reference ranges for the Quidel C1inhF enzyme-linked immunosorbent assay (ELISA) system appear to be too low, with a sensitivity of just 57% for HAE. Following optimization of the reference ranges using receiver operating characteristic analysis, low C1inhF was found to be 78% sensitive and 100% specific for HAE. The diagnosis of HAE is not excluded by normal levels of complement C4. We conclude that C1 inhibitor studies should be performed regardless of serum C4 where a high index of clinical suspicion exists. (+info)
Recurrent angioedema due to lysozyme allergy.
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A 54-year-old woman suffered an episode of dyspnea and edema affecting her eyelids, tongue, and lips a few minutes after intake of Lizipaina (bacitracin, papain, and lysozyme). She was treated with intravenous drugs and her symptoms improved within 2 hours. She had experienced 3 to 4 bouts of similar symptoms related to the ingestion of cured cheeses or raw egg. Specific serum immunoglobulin (Ig) E against lysozyme was present at a concentration of 0.45 kU/L, and no specific IgE was found against egg white and yolk, ovalbumin, or ovomucoid. Skin prick tests were positive with commercial extracts of egg white and lysozyme but doubtful with yolk, ovalbumin, and ovomucoid. Prick-to-prick tests with raw egg white and yolk gave positive results, but negative results were obtained with cooked egg white and yolk and 5 brands of cheese (3 of them containing lysozyme and the other 2 without lysozyme). Controlled oral administration of papain, bacitracin, and cheeses without lysozyme was well tolerated. We suggest that the presence of lysozyme in a pharmaceutical preparation, cured cheese, and raw egg was responsible for the symptoms suffered by our patient, probably through an IgE-mediated mechanism. (+info)
Management of hereditary angioedema in pediatric patients.
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Hereditary angioneurotic edema is a rare disorder caused by the congenital deficiency of C1 inhibitor. Recurring angioedematous paroxysms that most commonly involve the subcutis (eg, extremities, face, trunk, and genitals) or the submucosa (eg, intestines and larynx) are the hallmarks of hereditary angioneurotic edema. Edema formation is related to reduction or dysfunction of C1 inhibitor, and conventional therapy with antihistamines and corticosteroids is ineffective. Manifestations occur during the initial 2 decades of life, but even today there is a long delay between the onset of initial symptoms and the diagnosis of hereditary angioneurotic edema. Although a variety of reviews have been published during the last 3 decades on the general management of hereditary angioneurotic edema, little has been published regarding management of pediatric hereditary angioneurotic edema. Thus, we review our experience and published data to provide an approach to hereditary angioneurotic edema in childhood. (+info)