LAD-III, a leukocyte adhesion deficiency syndrome associated with defective Rap1 activation and impaired stabilization of integrin bonds

Recently, we reported a rare leukocyte adhesion deficiency (LAD) associated with severe defects in integrin activation by chemokine signals, despite normal ligand binding of leukocyte integrins.(1) We now report that the small GTPase, Rap1, a key regulator of inside-out integrin activation is abnormally regulated in LAD Epstein-Barr virus (EBV) lymphocyte cells. Both constitutive and chemokine-triggered activation of Rap1 were abolished in LAD lymphocytes despite normal chemokine signaling. Nevertheless, Rap1 expression and activation by phorbol esters were intact, ruling out an LAD defect in Rap1 guanosine triphosphate (GTP) loading. The very late antigen 4 (VLA-4) integrin abnormally tethered LAD EBV lymphocytes to its ligand vascular cell adhesion molecule 1 (VCAM-1) under shear flow due to impaired generation of high-avidity contacts despite normal ligand binding and intact avidity to surface-bound anti-VLA-4 monoclonal antibody (mAb). Thus, a defect in constitutive Rap1 activation results in an inability of ligand-occupied integrins to generate high-avidity binding to ligand under shear flow. This is a first report of an inherited Rap1 activation defect associated with a pathologic disorder in leukocyte integrin function, we herein term it "LAD-III."     

Combined clotting factor deficiencies: experience at a single hemophilia treatment center

We describe a series of patients with combined factor deficiencies and von Willebrand's disease (VWD) at one haemophilia treatment centre. Although the incidence of VWD is at least 1% in the general population, combined coagulation defects have been infrequently described in the medical literature and are likely under diagnosed. This entity should be considered in patients with a known factor deficiency and either an unexpectedly severe bleeding phenotype, or bleeding that is unresponsive to factor replacement.     

Early elective surgery for bleeding ulcer in the posterior duodenal bulb. Own results and review of the literature

BACKGROUND/AIMS: Acute upper gastrointestinal bleeding represents the major, potentially life-threatening complication of gastroduodenal ulcer disease with an average mortality of 10%. To decrease mortality a risk-dependent combined endoscopic and operative approach for the treatment of bleeding ulcer in the posterior duodenal wall was developed. METHODOLOGY: Between 1998 and 2000 in our hospital a total of 22 patients with bleeding posterior duodenal bulb ulcer were treated following a differentiated endoscopic-surgical concept. High-risk patients with high bleeding activity (n = 8) underwent early elective surgery after primary endoscopic treatment of the bleeding and stabilization of the patient in an intensive care unit. The management of patients presenting a low-risk profile (n = 14) included careful surveillance and a consecutive second endoscopy 24 hours after the initial endoscopy. RESULTS: Patients that underwent surgery showed more severe secondary diseases than patients of the endoscopic group. Hemoglobin concentration in patients requiring surgery was significantly lower, they showed a higher incidence of hypovolemic shock and received more blood transfusions within the first 24 hours. Mortality was 0% in both groups, a relevant rebleeding occurred in one patient after endoscopic therapy, which was successfully treated by reendoscopy with fibrin injection. CONCLUSIONS: Due to these results as well as results of other groups we recommend early elective surgery in high-risk patients with bleeding duodenal bulb ulcer after primary endoscopic treatment of the bleeding.     

A variant form of Bernard-Soulier syndrome: mild haemostatic defect associated with partial platelet GPIb deficiency

Platelets from patients with Bernard-Soulier syndrome (BSS) are larger than normal and demonstrate characteristic aggregation abnormalities. A molecular defect involving platelet membrane glycoproteins has been established as the primary abnormality, and the major defect is described as an absence of GPIb, the receptor for von Willebrand factor, which prevents the adhesion of BSS platelets to damaged endothelium. Associated deficiencies of GPV and GPIX are also recognized. The overall clinical effect is a haemorrhagic tendency which, although variable, is severe at times in all patients. We report a child who presented with the typical morphological and aggregation abnormalities associated with BSS, but who had negligible bleeding problems. Further investigation revealed a significant but incomplete deficiency of GPIb and of GPV and GPIX. This case suggests that BSS may be a heterogeneous disorder with clinical consequences dependent on the extent and complexity of the platelet membrane glycoprotein deficiency.     

Perioperative management of MYH9 hereditary macrothrombocytopenia (Fechtner syndrome)

OBJECTIVE: Hereditary thrombocytopenias characterized by mutations in the gene for non-muscle myosin heavy chain IIA (NMMHC-IIA) are known as MYH9-related hereditary macrothrombocytopenia, and include the May-Hegglin anomaly, Sebastian platelet syndrome, Fechtner syndrome, and Epstein syndrome. Despite the presence of thrombocytopenia, these patients often have only mild or non-bleeding phenotypes. A major risk for these patients can be inappropriate treatment with long-term corticosteroids or splenectomy for misdiagnosed chronic autoimmune thrombocytopenia, as well as inadequate peri- and postoperative management. METHODS: Using the case of a 44-yr-old male with Fechtner syndrome (macrothrombocytopenia, leukocyte inclusions, sensorineural deafness, glomerulonephritis) who underwent neurosurgery for an intracerebral arteriovenous malformation, we describe current methods to diagnose hereditary MYH9-related macrothombocytopenia by analysis of the blood smear, immunofluorescence staining of the NMMHC-IIA in leucocytes, and by MYH9-gene sequencing. RESULTS: Clusters of NMMHC-IIA in granulocytes and a R1165C mutation in the MYH9-gene in two macrothrombocytopenic family members confirmed the diagnosis of a MYH9-related disease. The patient had no bleeding diathesis by history or physical examination. Thus no perioperative prohemostatic pharmacologic therapies or transfusions were given, with only minimal bleeding observed. Postoperative antithrombotic thromboprophylaxis was not given because of anticipated enhanced risk for bleeding. However, the patient developed symptomatic pulmonary embolism on postoperative day 6, which was successfully managed with 8 months of anticoagulation. CONCLUSION: MYH9-related hereditary macrothrombocytopenia does not necessarily protect against postoperative venous thromboembolism, and affected patients who do not evince bleeding diathesis should be considered for routine postoperative pharmacologic thromboprophylaxis.     

Treatment of von Willebrand disease

Summary. von Willebrand disease is the most frequent of inherited bleeding disorders (1:100 affected individuals in the general population). The aim of treatment is to correct the dual defects of haemostasis, i.e., abnormal coagulation expressed by low levels of factor VIII and abnormal platelet adhesion expressed by a prolonged bleeding time. There are two main options available for the management of von Willebrand disease: desmopressin and transfusion therapy with blood products. Desmopressin is the treatment of choice in patients with type 1 von Willebrand disease, who account for approximately 80% of cases. This pharmacological compound raises endogenous factor VIII and von Willebrand factors and thereby corrects the intrinsic coagulation defect and the prolonged bleeding time in most type 1 patients. In type 3 and in the majority of type 2 patients desmopressin is not effective, and it is necessary to resort to plasma concentrates containing factor VIII and von Willebrand factor. Treated with virucidal methods, these concentrates are effective and currently safe, but the bleeding time defect is not always corrected by them. Platelet concentrates or desmopressin can be used as adjunctive treatments when poor correction of the bleeding time after concentrates is associated with continued bleeding.     

Analysis of 65 pregnancies in 34 women with five different forms of inherited platelet function disorders

This study evaluated 65 pregnancies in 34 women with five different inherited platelet function disorders. Gestation was similar to that of the general population. Severe bleeds requiring blood transfusions were observed in 50% of deliveries in Glanzmann thrombasthenia (GT), but not in the patients with delta storage pool disease, Hermansky‐Pudlak syndrome, P2Y12 defect or defect of thromboxane A2 receptor. Of note, severe haemorrhage also occurred in women with GT who had received prophylactic platelet transfusions, suggesting that better preventive treatments are required. Diagnosis and degree of spontaneous bleeding tendency before pregnancy were reliable parameters to predict the delivery‐related bleeding risk.     

Recurrent life-threatening epistaxis in a child with Bernard-Soulier syndrome controlled by bilateral ligation of external carotids and ethmoidal arteries

Bilateral ligation of external carotids and ethmoidal arteries proved successful in controlling severe recurring epistaxis in a 13-year-old patient with Bernard-Soulier syndrome. In this child, epistaxis was the major bleeding symptom. Despite massive substitutive therapy, the patient suffered several life-threatening episodes of hypovolaemic shock. Although epistaxis is not reported as a cause of death in patients with haemostasis defect, our case might suggest that in selected cases with inherited platelet defect and intractable epistaxis so severe as to make normal or near-normal life impossible, surgical treatment could be considered.     

The role of platelet membrane glycoproteins Ib and IIb-IIIa in platelet adherence to human artery subendothelium

Platelet adherence to human artery subendothelium in blood from eight normal subjects, four patients with Glanzmann's thrombasthenia (deficiency of platelet membrane glycoproteins IIb and IIIa: GPIIb-IIIa), two patients with Bernard-Soulier syndrome (deficiency of platelet membrane glycoprotein Ib: GPIb) and one patient with von Willebrand's disease (VWD subtype III. deficient in factor VIII-von Willebrand factor: FVIII-VWF) was compared at various wall shear rates (300, 500, 1000, 1800 and 2500 s-1). Platelet adherence in blood from the patients with Glanzmann's thrombasthenia was within the normal range at shear rates below 1000 s-1. There was some decrease in adhesion at higher shear rates and platelets were less spread out on the subendothelium than normally at all shear rates. Platelet aggregate formation was almost totally absent. Platelet adherence in blood from patients with the Bernard-Soulier syndrome was strongly impaired at all shear rates. Platelet adherence in blood from the patient with VWD subtype III was normal at shear rates of 300 and 500 s-1, but impaired at shear rates above 1000 s-1. Aggregate formation was also decreased at these shear rates. Platelet adhesion was strongly inhibited by a monoclonal antibody against glycoprotein Ib, which had previously been shown to inhibit ristocetin-induced aggregation, at shear rates of 500 and 1800 s-1 but not at 300 s-1. Platelet adhesion at 1800 s-1 was also inhibited, though to a lesser extent, by two antibodies against GPIIb-IIIa. These antibodies also inhibited platelet aggregate formation. The data indicates that GPIb is involved in adhesion at the same shear rates as von Willebrand factor. Absence or inhibition of GPIIb-IIIa primarily causes a defect of aggregate formation but GPIIb-IIIa may also play a role in adhesion, particularly at high shear rates. The defect of adhesion in the Bernard-Soulier syndrome may be dependent on factors other than a deficiency of GPIb alone.     

Brown-Vialetto-Van Laere and Fazio Londe syndrome is associated with a riboflavin transporter defect mimicking mild MADD: a new inborn error of metabolism with potential treatment

We report on three patients (two siblings and one unrelated) presenting in infancy with progressive muscle weakness and paralysis of the diaphragm. Metabolic studies revealed a profile of plasma acylcarnitines and urine organic acids suggestive of a mild form of the multiple acyl-CoA dehydrogenation defect (MADD, ethylmalonic/adipic acid syndrome). Subsequently, a profound flavin deficiency in spite of a normal dietary riboflavin intake was established in the plasma of all three children, suggesting a riboflavin transporter defect. Genetic analysis of these patients demonstrated mutations in the C20orf54 gene which encodes the human homolog of a rat riboflavin transporter. This gene was recently implicated in the Brown-Vialetto-Van Laere syndrome, a rare neurological disorder which may either present in infancy with neurological deterioration with hypotonia, respiratory insufficiency and early death, or later in life with deafness and progressive ponto-bulbar palsy. Supplementation of riboflavin rapidly improved the clinical symptoms as well as the biochemical abnormalities in our patients, demonstrating that high dose riboflavin is a potential treatment for the Brown-Vialetto-Van Laere syndrome as well as for the Fazio Londe syndrome which is considered to be the same disease entity without the deafness.     

Role of the small GTPase Rap1 for integrin activity regulation in endothelial cells and angiogenesis

Ras-associated protein 1 (Rap1), a small GTPase, attracted attention because of its involvement in several aspects of cell adhesion, including integrin- and cadherin-mediated adhesion. Yet, the role of Rap1 genes and of Rap1 effectors for angiogenesis has not been investigated. Human umbilical vein endothelial cells (HUVECs) express Rap1a and Rap1b mRNA. To determine the contribution of Rap1 activity for angiogenesis, we overexpressed Rap1GAP1, a GTPase-activating protein that inhibits Rap1 activity. Overexpression of Rap1GAP1 significantly blocked angiogenic sprouting and tube-forming activity of HUVECs as well as migration and integrin-dependent adhesion. Silencing of Rap1a, Rap1b, or both significantly blocked HUVECs sprouting under basal and basic fibroblast growth factor-stimulated conditions and reduced HUVEC migration and integrin-dependent adhesion. We found that Rap1a and Rap1b are essential for the conformational activation of beta(1)-integrins in endothelial cells. Furthermore, silencing of Rap1a and Rap1b prevented phosphorylation of tyrosine 397 in focal adhesion kinase (FAK) and vascular endothelial growth factor-induced Akt1-activation. Rap1a(-/-)-deficient and Rap1a(+/-) heterozygote mice displayed reduced neovascularization after hind limb ischemia compared with wild-type mice. Silencing of RAPL significantly blocked the Rap1-induced sprouting of HUVECs, suggesting that the angiogenic activity of Rap1 is partly mediated by RAPL. Our data demonstrate a critical role of Rap1 in the regulation of beta(1)-integrin affinity, adhesion, and migration in endothelial cells and in postnatal neovascularization.     

Role of Rap1 in promoting sickle red blood cell adhesion to laminin via BCAM/LU

Vaso-occlusion is a hallmark of sickle cell disease. Agonist-induced activation of sickle red blood cells (SS RBCs) promotes their adhesion to vascular proteins, potentially contributing to vasoocclusion. Previously, we described a cyclic adenosine monophosphate (cAMP)-dependent increase in SS RBC adhesion to laminin. Here, we investigated whether Rap1, a small guanosine triphosphatase (GTPase) known to promote integrin-mediated adhesion in other cells, was involved in this signaling pathway. We found that agonists known to induce cAMP signaling promoted the GTP-bound, active state of Rap1 in SS RBCs. The cAMP-dependent exchange factor Epac (exchange protein directly activated by cAMP) is a likely upstream activator of Rap1, since Epac is present in these cells and the Epac-specific cAMP analog 8CPT-2-Me (8-(4-cholorophenylthio)-2'-O-methyl-cAMP) activated Rap1 and promoted SS RBC adhesion to laminin. This 8CPT-2-Me-stimulated adhesion was integrin independent, since it was insensitive to RGD peptide or antibodies against the only known integrin on SS RBCs, alpha4beta1. However, this adhesion was completely inhibited by either a soluble version of basal cell adhesion molecule/Lutheran (BCAM/LU) or a BCAM/LU adhesion-blocking anti-body. Surprisingly, 8CPT-2-Me-activated Rap1 did not promote SS RBC adhesion to a known alpha4beta1 ligand, vascular cell adhesion molecule 1 (VCAM-1). These results demonstrate that Epac-induced Rap1 activation in SS RBCs promotes BCAM/LU-mediated adhesion to laminin. Thus, Epac-mediated Rap1 activation may represent an important signaling pathway for promoting SS RBC adhesion.     

How I treat patients with von Willebrand disease

Von Willebrand disease (vWD) is a frequent inherited disorder of hemostasis that affects both sexes. Two abnormalities are characteristic of the disease, which is caused by a deficiency or a defect in the multimeric glycoprotein called von Willebrand factor: low platelet adhesion to injured blood vessels and defective intrinsic coagulation owing to low plasma levels of factor VIII. There are 2 main options available for the treatment of spontaneous bleeding episodes and for bleeding prophylaxis: desmopressin and transfusional therapy with plasma products. Desmopressin is the treatment of choice for most patients with type 1 vWD, who account for approximately 70% to 80% of cases. This nontransfusional hemostatic agent raises endogenous factor VIII and von Willebrand factor 3 to 5 times and thereby corrects both the intrinsic coagulation and the primary hemostasis defects. In patients with the more severe type 3 and in most patients with type 2 disease, desmopressin is ineffective or is contraindicated and it is usually necessary to resort to plasma concentrates containing both factor VIII and von Willebrand factor. Concentrates treated with virucidal methods should be preferred to cryoprecipitate because they are equally effective and are perceived as safer. (Blood. 2001;97:1915-1919)     

Laboratory monitoring of replacement therapy for major surgery in von Willebrand disease

Von Willebrand disease (VWD) is an inherited haemorrhagic disorder caused by a quantitative or qualitative defect of von Willebrand factor (VWF), a multimeric plasma glycoprotein that plays a key role in platelet adhesion to the subendothelium and acts as a carrier of factor VIII (FVIII) in blood. Patients with VWD experience bleeding symptoms that are mainly localized in mucous membranes and soft tissues, and their severity depends on the degree of the primary reduction in VWF and the secondary deficiency of FVIII in plasma. Because VWD patients are also at increased risk of perioperative bleeding, a prophylactic treatment aimed to correct the dual haemostatic defect (i.e. VWF and FVIII) is warranted. This review summarizes knowledge on the current management of patients undergoing major surgery, focusing on the peri‐surgical laboratory monitoring of replacement therapy with VWF/FVIII concentrates. We suggest to monitor plasma levels of FVIII coagulant activity in the postoperative period rather than a surrogate maker of platelet‐binding VWF activity as the ristocetin cofactor assay and its recent modifications.     

Transfusion strategies for traumatic coagulopathy

Uncontrolled bleeding is the most common preventable cause of death for patients with severe injury. Coagulopathy inevitably accompanies severe bleeding, exacerbated by the ongoing blood loss and the treatments administered. There is debate about the underlying pathophysiological mechanisms of early traumatic coagulopathy and uncertainty about whether injury induces a unique coagulopathy when compared to other forms of major haemorrhage. This review describes current understanding of the coagulopathy of major blood loss and focuses on the early coagulation changes that occur following severe injury. It then reports on the contemporary management of coagulopathic bleeding using new transfusion strategies. Finally this review presents some practical points to the delivery of transfusion for major blood loss in the modern hospital setting.     

La maladie de Willebrand

Von Willebrand factor is involved in primary hemostasis (adhesion of platelets to subendothelium and platelet aggregation) and acts as the carrier of coagulation factor VIII. Von Willebrand disease, resulting from a quantitative or qualitative defect of this factor, is the most frequent inherited bleeding disorder. It is mainly responsible for symptoms such as mucocutaneous bleeding and excessive bleeding after trauma or invasive procedures, but can also cause gastro-intestinal bleeding or hemarthrosis in the most severe forms of the disease. There are numerous causes of physiological variation of von Willebrand factor plasma levels which can be responsible for diagnostic difficulty or changes in symptoms over time. Diagnosis relies primarily on clinical symptoms but requires the use of several laboratory analyses: von Willebrand factor activity and antigen testing and factor VIII activity. More specialized assays allow classification of the disease in various types and subtypes which imply different management strategies (types 1, 2A, 2B, 2M, 2N, and 3). Treatment is based on desmopressin, responsible for an increase in plasma concentration of von Willebrand factor, and plasma-derived von Willebrand factor concentrates which can be combined with factor VIII.     

3M syndrome: a report of four cases in two families

3M syndrome is a rare entity characterized by severe growth retardation, dysmorphic features and skeletal changes as its major components. It is differentiated from other types of dwarfism by its clinical features and by the typical slender long bones and foreshortened vertebral bodies that can be visualized radiographically. 3M syndrome has an autosomal recessive mode of inheritance. An early diagnosis is important for genetic counseling. In this report, we present four children (3 males, 1 female) from two families who were aged between 4(11/12) and 10(11/12) years and had clinical findings of 3M syndrome. One of these patients had received growth hormone (GH) treatment which was discontinued due to an inadequate height gain. Physicians should be aware of this entity in the differential diagnosis of children with severe short stature and mild skeletal changes.     

Platelet adhesion defect in type I Gaucher Disease is associated with a risk of mucosal bleeding

Patients with type I Gaucher Disease (GD) may have a clinically significant bleeding tendency that is disproportionate to their platelet count. We hypothesized that impaired platelet adhesion might contribute to bleeding tendency. Adult patients with type I GD with platelet counts ≥130×10(9) /l and haematocrit ≥30% (n=48), obligatory carriers (n=52), and healthy controls (n=19) were studied. Platelet adhesion, using the IMPACT-R (Cone and Plate(let) Analyser), and platelet aggregation were determined. Type I GD patients had significantly lower platelet adhesion [surface coverage %, median (interquartile range)] 4·6 (3·2-7·5), compared to controls, 8·7 (7·6-10·3), or carriers, 8·1 (6·5-9·4; P=0·001). Platelet adhesion was not affected by the use of disease-specific enzyme replacement therapy but was improved in patients after splenectomy, 7·2 (5·8-9·3). Mixing tests showed that the reduced adhesion was an intrinsic platelet defect. Mucosal bleeding was reported in 17 (35·4%) patients and was associated with abnormal adhesion [P=0·037, with an Odds Ratio (95% confidence interval) of 5·73 (1·1-29·6)]. Five patients (22%) had reduced platelet aggregation, all of whom had reduced platelet adhesion. Platelet aggregation defect was not associated with mucosal bleeding. In conclusion, platelet adhesion defect is a major thrombocytopathy in type I GD patients and can explain part of the increased tendency to bleeding.     

替格瑞洛联合阿司匹林治疗急性冠脉综合征的临床观察

目的观察替格瑞洛联合阿司匹林治疗急性冠状动脉（冠脉）综合征的临床疗效及安全性。方法将抽取的100例急性冠脉综合征患者随机（电脑随机数字表法）分为两组：对照组（阿司匹林组）50例和观察组（替格瑞洛联合阿司匹林）50例。治疗3个月,观察两组临床疗效和主要心血管事件。结果观察组临床疗效显著优于对照组。此外,对照组主要心血管事件发生率为30％,显著高于观察组的8％,差异有统计学意义（P〈0．05）。两组血小板聚集率、全血黏度和血浆黏度均降低,与治疗前比较,差异有统计学意义（P〈0．05）;观察组比对照组更显著。结论替格瑞洛联合阿司匹林可以显著改善急性冠脉综合征患者的临床疗效和体征,可以降低患者的主要心血管事件风险,而不增加严重出血,治疗效果显著。     

急性出血性直肠溃疡综合征6例临床分析

目的探讨急性出血性直肠溃疡综合征在中国人群的临床特点、治疗及预后。方法 2009年1月-2011年12月北京军区总医院收治的6例急性直肠溃疡综合征患者。总结6例患者的临床特征、内镜表现、治疗方法和预后。结果在6例患者中,5例为老年女性(83.3%),1例为男性(16.7%)。结肠镜下可见孤立或多发的直肠溃疡,呈圆形、不规则性,以及类似Dieulafoy病的溃疡,距齿状线5.7 cm。83.3%(5/6)止血成功,4例为局部针对性止血治疗,1例为局部治疗联合血管造影。死亡2例,1例因反复出血,行直肠切除术后第7天出现全身多器官功能衰竭,导致死亡;1例止血成功,因基础疾病肝功能衰竭死亡。结论急性出血性直肠溃疡综合征是一种少见病,但危及生命,应增强临床意识,早期诊断并选择合适的治疗方法,预后较好。