Mice lacking the signaling molecule CalDAG-GEFI represent a model for leukocyte adhesion deficiency type III

Single gene mutations in beta integrins can account for functional defects of individual cells of the hematopoietic system. In humans, mutations in beta(2) integrin lead to leukocyte adhesion deficiency (LAD) syndrome and mutations in beta(3) integrin cause the bleeding disorder Glanzmann thrombasthenia. However, multiple defects in blood cells involving various beta integrins (beta(1), beta(2), and beta(3)) occur simultaneously in patients with the recently described LAD type III (LAD-III). Here we show that the product of a single gene, Ca(2+) and diacylglycerol-regulated guanine nucleotide exchange factor I (CalDAG-GEFI), controlled the activation of all 3 integrins in the hematopoietic system. Neutrophils from CalDAG-GEFI(-/-) mice exhibited strong defects in Rap1 and beta(1) and beta(2) integrin activation while maintaining normal calcium flux, degranulation, and ROS generation. Neutrophils from CalDAG-GEFI-deficient mice failed to adhere firmly to stimulated venules and to migrate into sites of inflammation. Furthermore, CalDAG-GEFI regulated the activation of beta(1) and beta(3) integrins in platelets, and CalDAG-GEFI deficiency caused complete inhibition of arterial thrombus formation in mice. Thus, mice engineered to lack CalDAG-GEFI have a combination of defects in leukocyte and platelet functions similar to that of LAD-III patients.     

Soluble leptin receptor and leptin levels in pregnant women before and after delivery

Soluble leptin receptor is an extracellular domain of the leptin receptor that serves as the main leptin-binding protein and may play a role in the regulation of leptin tissue effects. The aim of our study was to assess serum concentrations of leptin, soluble leptin receptor, and other hormones involved in the regulation of leptin secretion in pregnant women before and after delivery. Serum leptin, cortisol, and tumor necrosis factor alpha (TNF-alpha) concentrations in 19 pregnant women before delivery were significantly higher than in healthy nonpregnant women (33.3+/-21.0 vs. 7.9+/-3.5 ng/mL, 1068.9+/-442.2 vs. 546.6+/-165.3 nmol/L, 4.4+/-1.1 vs. 3.4+/-1.2 ng/mL, respectively). In contrast, no differences between these groups were found in soluble leptin receptor levels. Delivery significantly decreased serum leptin and cortisol levels and increased soluble leptin receptor levels (12.3+/-9.1 ng/mL, 749.6+/-205.3 nmol/L, 23.3+/-7.9 U/mL, respectively). Soluble leptin receptor levels after delivery became higher than in the control group. We conclude that serum leptin and serum soluble leptin-receptor levels are significantly affected by pregnancy and delivery. The regulation of leptin levels in this group of patients appears to be distinct and independent of soluble leptin-receptor levels.     

Plasma concentrations of fibroblast growth factors 19 and 21 in patients with anorexia nervosa

Context: Fibroblast growth factor 19 (FGF19) and FGF21 are novel metabolic regulators that improve insulin sensitivity and decrease adiposity in mice. However, little is known about the nutritional regulation of these factors in humans. Objective: The objective of this study was to measure plasma FGF19 and FGF21 levels in patients with anorexia nervosa (AN) and to explore its relationship with anthropometric and endocrine parameters. Design: This was a single-center cross-sectional study. Setting: The study was performed in a university hospital. Patients: Seventeen untreated women with a restrictive type of AN and 17 healthy women (control group) were included. Main Outcome Measures: Fasting plasma FGF19 and FGF21, serum insulin, leptin, soluble leptin receptor, adiponectin, resistin, and C-reactive protein were the main outcome measures. Results: Plasma FGF19 levels did not significantly differ between the groups studied, whereas plasma FGF21 levels were significantly reduced in AN relative to the control group. Plasma FGF21 positively correlated with body mass index and serum leptin and insulin and was inversely related to serum adiponectin in both groups. In contrast, plasma FGF19 was not related to any of parameters studied. Partial realimentation significantly reduced plasma FGF21 levels in AN. Conclusion: Circulating levels of FGF21 but not FGF19 are strongly related to body weight and serum levels of leptin, adiponectin, and insulin in both anorectic and normal-weight women. We suggest that reduced plasma FGF21 levels could be involved in the pathophysiology of AN or in a complex adaptive response to this disease.     

3-Dimensional Echocardiographic Analysis of the Tricuspid Annulus Provides New Insights Into Tricuspid Valve Geometry and Dynamics

Objectives

The authors used transthoracic 3-dimensional transthoracic echocardiography (3DE) to characterize tricuspid annulus (TA) geometry and dynamics in healthy volunteers.

von Willebrand factor and factor VIII are independently required to form stable occlusive thrombi in injured veins

von Willebrand factor (VWF) protects factor VIII (FVIII) from proteolysis and mediates the initial contact of platelets with the injured vessel wall, thus playing an important role in hemostasis and thrombosis. VWF is crucial for the formation of occlusive thrombi at arterial shear rates. However, with only a few conflicting studies published, the role of VWF in venous thrombosis is still unclear. Using gene-targeted mice, we show that in ferric chloride-injured veins platelet adhesion to subendothelium is decreased and thrombus growth is impaired in VWF(-/-) mice when compared with wild type (WT). We also observed increased embolization in the VWF(-/-) mice, which was due to lower FVIII levels in these mice as recombinant factor VIII (r-FVIII) restored thrombus stability. Despite normalization of blood clotting time and thrombus stability after r-FVIII infusion, the VWF(-/-) venules did not occlude. Transgenic platelets lacking the VWF receptor GPIbalpha extracellular domain showed decreased adhesion to injured veins. But, after a delay, all the injured venules occluded in these transgenic mice. Thus, VWF likely uses other adhesion receptors besides GPIbalpha in thrombus growth under venous shear conditions. Our studies document crucial roles for VWF and FVIII in experimental thrombosis under venous flow conditions in vivo.     

The role of HLA-DRB1 alleles on susceptibility and outcome of a Portuguese Multiple Sclerosis population

BACKGROUND: The association between susceptibility to multiple sclerosis (MS) and HLA-DRB1*15 has been reported in various European populations. OBJECTIVE: To investigate the relationship between MS, HLA-DRB1*15 and other DRB1 alleles in a Portuguese population and their association with clinical course of MS. METHODS: The HLA-DRB1 alleles were analyzed by PCR-SSP in 248 MS patients and 282 healthy controls. In order to relate HLA-DRB1 alleles to disease aggressiveness, patients with relapsing remitting MS and secondary progressive MS were subdivided into 3 groups: 'benign' MS patients who maintain an Extended Disability Status Scale (EDSS) score of 3 after the same period and 'aggressive' MS those with EDSS>or=6 within 15 years of disease onset. RESULTS: As expected, a higher frequency of HLA-DRB1*15 was found in MS patients (29.8% vs 19.9%, odds ratio (OR)=1.72, 95% CI=1.15-2.56, p=0.008). The HLA-DRB1*03 allele was positively associated with MS in the overall patient population (22.6% vs 15.6%, OR=1.58, 95% CI=1.02-2.45). Concerning disease aggressiveness, HLA-DRB1*15 occurred more frequently in the group with benign disease (42.6% vs 19.9%, OR=2.99, 95% CI=1.56-5.72) and in the group with non-benign disease (34.1% vs 19.9%, OR=2.09, 95% CI=1.05-4.16) compared with controls. When time to reach an EDSS=3 or EDSS=6 was considered as end point, HLA-DRB1*15 negative patients were found to have a worse prognosis. CONCLUSIONS: In this population of Portuguese MS patients, the HLA-DRB1*15 allele is established as a genetic marker for susceptibility to MS and is also associated with a better outcome.