Bleeding due to disruption of a cargo-specific ER-to-Golgi transport complex.

Mutations in LMAN1 (also called ERGIC-53) result in combined deficiency of factor V and factor VIII (F5F8D), an autosomal recessive bleeding disorder characterized by coordinate reduction of both clotting proteins. LMAN1 is a mannose-binding type 1 transmembrane protein localized to the endoplasmic reticulum-Golgi intermediate compartment (ERGIC; refs. 2,3), suggesting that F5F8D could result from a defect in secretion of factor V and factor VIII (ref. 4). Correctly folded proteins destined for secretion are packaged in the ER into COPII-coated vesicles, which subsequently fuse to form the ERGIC. Secretion of certain abundant proteins suggests a default pathway requiring no export signals (bulk flow; refs. 6,7). An alternative mechanism involves selective packaging of secreted proteins with the help of specific cargo receptors. The latter model would be consistent with mutations in LMAN1 causing a selective block to export of factor V and factor VIII. But approximately 30% of individuals with F5F8D have normal levels of LMAN1, suggesting that mutations in another gene may also be associated with F5F8D. Here we show that inactivating mutations in MCFD2 cause F5F8D with a phenotype indistinguishable from that caused by mutations in LMAN1. MCFD2 is localized to the ERGIC through a direct, calcium-dependent interaction with LMAN1. These findings suggest that the MCFD2-LMAN1 complex forms a specific cargo receptor for the ER-to-Golgi transport of selected proteins.

Gene expression profiling of dengue infected human primary cells identifies secreted mediators in vivo.

We used gene expression profiling of human primary cells infected in vitro with dengue virus (DENV) as a tool to identify secreted mediators induced in response to the infection. Affymetrix GeneChip analysis of human primary monocytes, B cells and dendritic cells infected with DENV in vitro showed strong induction of monocyte chemotactic protein 2 (MCP-2/CCL8), interferon gamma-induced protein 10 (IP-10/CXCL10) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/TNFSF10). The expression of these genes was confirmed in dendritic cells infected with DENV in vitro at mRNA and protein levels. A prospectively enrolled cohort of DENV-infected Venezuelan patients was used to measure the levels of these proteins in serum during three different periods of the disease. Results showed significant increase of MCP-2, IP-10, and TRAIL levels in patients infected with DENV during the febrile period, when compared to healthy donors and patients with other febrile illnesses. MCP-2 and IP-10 levels were still elevated during the post-febrile period while TRAIL levels dropped close to normal after defervescense. Patients with primary infections had higher TRAIL levels than patients with secondary infections during the febrile period of the disease. Increased levels of IP-10, TRAIL and MCP-2 in acute DENV infections suggest a role for these mediators in the immune response to the infection. MCP-2 was identified in this work as a new unreported and important dengue-related protein and IP-10 was confirmed as a novel and strong pro-inflammatory marker in acute disease.

Elevated levels of soluble ST2 protein in dengue virus infected patients.

Levels of the soluble form of the interleukin-1 receptor-like 1 protein (IL-1RL-1/ST2) are elevated in the serum of patients with diseases characterized by an inflammatory response. The objective of this study was to determine the concentration of soluble ST2 (sST2) in dengue infected patients during the course of the disease. Twenty-four patients with confirmed dengue infection, classified as dengue fever, and 11 patients with other febrile illness (OFI) were evaluated. Levels of sST2 in serum and laboratory variables usually altered during dengue infections were measured. Dengue infected patients had higher serum sST2 levels than OFI at the end of the febrile stage and at defervescence (p=0.0088 and p=0.0004, respectively). Patients with secondary dengue infections had higher serum sST2 levels compared with patients with primary dengue infections (p=0.047 at last day of fever and p=0.030 at defervescence). Furthermore, in dengue infected patients, we found a significant negative correlation of sST2 with platelet and WBC counts, and positive correlation with thrombin time and transaminases activity. We suggest that sST2 could be a potential marker of dengue infection, could be associated with severity or could play a role in the immune response in secondary dengue virus infection.

Development of standard clinical endpoints for use in dengue interventional trials.

Dengue is a major public health problem worldwide. Although several drug candidates have been evaluated in randomized controlled trials, none has been effective and at present, early recognition of severe dengue and timely supportive care are used to reduce mortality. While the first dengue vaccine was recently licensed, and several other candidates are in late stage clinical trials, future decisions regarding widespread deployment of vaccines and/or therapeutics will require evidence of product safety, efficacy and effectiveness. Standard, quantifiable clinical endpoints are needed to ensure reproducibility and comparability of research findings. To address this need, we established a working group of dengue researchers and public health specialists to develop standardized endpoints and work towards consensus opinion on those endpoints. After discussion at two working group meetings and presentations at international conferences, a Delphi methodology-based query was used to finalize and operationalize the clinical endpoints. Participants were asked to select the best endpoints from proposed definitions or offer revised/new definitions, and to indicate whether contributing items should be designated as optional or required. After the third round of inquiry, 70% or greater agreement was reached on moderate and severe plasma leakage, moderate and severe bleeding, acute hepatitis and acute liver failure, and moderate and severe neurologic disease. There was less agreement regarding moderate and severe thrombocytopenia and moderate and severe myocarditis. Notably, 68% of participants agreed that a 50,000 to 20,000 mm3 platelet range be used to define moderate thrombocytopenia; however, they remained divided on whether a rapid decreasing trend or one platelet count should be case defining. While at least 70% agreement was reached on most endpoints, the process identified areas for further evaluation and standardization within the context of ongoing clinical studies. These endpoints can be used to harmonize data collection and improve comparability between dengue clinical trials.

Rapid antigen tests for dengue virus serotypes and Zika virus in patient serum.

The recent Zika virus (ZIKV) outbreak demonstrates that cost-effective clinical diagnostics are urgently needed to detect and distinguish viral infections to improve patient care. Unlike dengue virus (DENV), ZIKV infections during pregnancy correlate with severe birth defects, including microcephaly and neurological disorders. Because ZIKV and DENV are related flaviviruses, their homologous proteins and nucleic acids can cause cross-reactions and false-positive results in molecular, antigenic, and serologic diagnostics. We report the characterization of monoclonal antibody pairs that have been translated into rapid immunochromatography tests to specifically detect the viral nonstructural 1 (NS1) protein antigen and distinguish the four DENV serotypes (DENV1-4) and ZIKV without cross-reaction. To complement visual test analysis and remove user subjectivity in reading test results, we used image processing and data analysis for data capture and test result quantification. Using a 30-µl serum sample, the sensitivity and specificity values of the DENV1-4 tests and the pan-DENV test, which detects all four dengue serotypes, ranged from 0.76 to 1.00. Sensitivity/specificity for the ZIKV rapid test was 0.81/0.86, respectively, using a 150-µl serum input. Serum ZIKV NS1 protein concentrations were about 10-fold lower than corresponding DENV NS1 concentrations in infected patients; moreover, ZIKV NS1 protein was not detected in polymerase chain reaction-positive patient urine samples. Our rapid immunochromatography approach and reagents have immediate application in differential clinical diagnosis of acute ZIKV and DENV cases, and the platform can be applied toward developing rapid antigen diagnostics for emerging viruses.

Substitution of Gly-548 to Ala in the substrate binding pocket of prothrombin Perijá leads to the loss of thrombin proteolytic activity.

Prothrombin Perijá is a dysprothrombin derived from a homozygous patient that manifests low thrombin activity upon activation in a one-stage assay. Purified prothrombin Perijá showed normal appearance on SDS-PAGE. and was cleaved normally to form alpha-thrombin by the prothrombinase complex. The activated form, thrombin Perijá, however, did not show any proteolytic activity towards native substrates, fibrinogen, protein C or various synthetic substrates for alpha-thrombin, but it was able to bind to antithrombin III, although the binding capacity was markedly reduced even in the presence of heparin. Thrombin Perijá showed full reactivity toward a small inhibitor, DFP, indicating that the molecular defect is in the substrate binding site in the thrombin molecule but not in the active site itself. By DNA sequence analysis of the patient prothrombin gene, we identified a G to C mutation at nucleotide 20016 in exon 14, which predicts a Gly-548 to Ala substitution in the prothrombin Perijá molecule. The structural modeling of thrombin Perijá suggests that Ala-548 is located close to the limb of the cavity wall of the substrate binding pocket, and that the methyl group blocks protrusion of the guanidino group of Arg into the cavity. This steric hindrance may well inhibit the access of Arg-containing substrates to the catalytic Ser-525 leading to the loss of proteolytic activity.

Biophysical characterization of fibrinogen Caracas I with an Aalpha-chain truncation at Aalpha-466 Ser: identification of the mutation and biophysical characterization of properties of clots from plasma and purified fibrinogen.

Fibrinogen Caracas I is a dysfibrinogenemia with a mild bleeding tendency; a novel nonsense mutation, in the gene coding the Aalpha-chain, identified in this study as G4731T, giving rise to a new stop codon at Aalpha-Glu 467. Fibrinogen from two family members, the mother and sister of the propositus, both heterozygous for the mutation were studied, analyzing clots made from both plasma and purified fibrinogen. Clot structure and properties were characterized by turbidity, permeation, scanning electron microscopy and rheological studies. Permeation through Caracas I plasma clots was decreased, consistent with the decreased final turbidity. As shown by scanning electron microscopy, plasma clots from the patients were composed of very thin fibers, with increased fibrin density and reduced pore size. Viscoelastic measurements revealed that fibrinogen Caracas I plasma clots were much stiffer and less subject to compaction. These results demonstrate a key role of the carboxyl-terminal alpha chains of fibrin in lateral aggregation during polymerization and reinforce the utility of studying plasma clots. It is important to point out that the biophysical studies with fibrinogen purified by two different methods yielded contradictory results, which can be accounted for by selective purification of certain molecular species as seen by two-dimensional electrophoresis.

A novel mutation (deletion of Aalpha-Asn 80) in an abnormal fibrinogen: fibrinogen Caracas VI. Consequences of disruption of the coiled coil for the polymerization of fibrin: peculiar clot structure and diminished stiffness of the clot.

An abnormal fibrinogen was identified in a 10-year-old male with a mild bleeding tendency; several years later, the patient developed a thrombotic event. Fibrin polymerization of plasma from the propositus and his mother, as measured by turbidity, was impaired. Plasmin digestion of fibrinogen and thrombin bound to the clot were both normal. The structure of clots from both plasma and purified fibrinogen was characterized by permeability, scanning electron microscopy and rheological measurements. Permeability of patients' clots was abnormal, although some measurements were not reliable because the clots were not mechanically stable. Consistent with these results, the stiffness of patients' clots was decreased approximately two-fold. Electron microscopy revealed that the patients' clots were very heterogeneous in structure. DNA sequencing of the propositus and his mother revealed a new unique point mutation that gives rise to a fibrinogen molecule with a missing amino acid residue at Aalpha-Asn 80. This new mutation, which would disrupt the alpha-helical coiled-coil structure, emphasizes the importance of this part of the molecule for fibrin polymerization and clot structure. This abnormal fibrinogen has been named fibrinogen Caracas VI.

Development of standard clinical endpoints for use in dengue interventional trials

Dengue is a major public health problem worldwide. Although several drug candidates have been evaluated in randomized controlled trials, none has been effective and at present, early recognition of severe dengue and timely supportive care are used to reduce mortality. While the first dengue vaccine was recently licensed, and several other candidates are in late stage clinical trials, future decisions regarding widespread deployment of vaccines and/or therapeutics will require evidence of product safety, efficacy and effectiveness. Standard, quantifiable clinical endpoints are needed to ensure reproducibility and comparability of research findings. To address this need, we established a working group of dengue researchers and public health specialists to develop standardized endpoints and work towards consensus opinion on those endpoints. After discussion at two working group meetings and presentations at international conferences, a Delphi methodology-based query was used to finalize and operationalize the clinical endpoints. Participants were asked to select the best endpoints from proposed definitions or offer revised/new definitions, and to indicate whether contributing items should be designated as optional or required. After the third round of inquiry, 70% or greater agreement was reached on moderate and severe plasma leakage, moderate and severe bleeding, acute hepatitis and acute liver failure, and moderate and severe neurologic disease. There was less agreement regarding moderate and severe thrombocytopenia and moderate and severe myocarditis. Notably, 68% of participants agreed that a 50,000 to 20,000 mm3 platelet range be used to define moderate thrombocytopenia; however, they remained divided on whether a rapid decreasing trend or one platelet count should be case defining. While at least 70% agreement was reached on most endpoints, the process identified areas for further evaluation and standardization within the context of ongoing clinical studies. These endpoints can be used to harmonize data collection and improve comparability between dengue clinical trials.

Radiosynoviorthesis in haemophilia: how safe?

One of the best procedures to prevent haemarthrosis in haemophilia has been radioactive synovectomy (radiosynoviorthesis). Since 1976 we have performed 119 radiosynoviortheses in 110 patients, aged from 3 to 40 years (mean 10), and of whom 71 were under 12 years of age. The knees were injected in 71, elbow in 29, ankles in 16, and shoulders in 3 cases. Clinical results of the procedure gave excellent results 80% of patients with no further bleeding. In the case of failure a reinjection can be given in the same joint at a 6 month interval. One of the criticisms against this method is possible chromosomal damage. In our centre, 4 studies have been made in order to see whether these changes are permanent, but all have demonstrated that chromosomal changes are reversible. Radioactive material used in 2 studies was Au-189. In 1978, 354 metaphases were studied with 61 ruptures, with 17.23% non-premalignant and 6 structural changes considered premalignant (1.69%). Further study was done in 1982, in the same group of patients with the result of 21 ruptures (3.34%) and no structural changes. The third study was performed in 13 patients that sustained radiosynoviorthesis with Re-186 in 1991. We compared the chromosomal study before and 6 months after the radioactive material injection and the results confirmed that changes appeared equally in non-irradiated and radiated patients and disappeared with time, never reaching the dangerous zone of 2%. In the group treated with Re-186 we studied an additional number of 130 metaphases with identical results and no structural changes. A study performed before and after radiosynoviorthesis with Y-90 revealed no premalignant changes. It seems than radiosynoviorthesis is safe and highly beneficial to haemophilic patients.

Increased activity of indoleamine 2,3-dioxygenase in serum from acutely infected dengue patients linked to gamma interferon antiviral function.

The depletion of l-tryptophan (L-Trp) has been associated with the inhibition of growth of micro-organisms and also has profound effects on T cell proliferation and immune tolerance. The enzyme indoleamine 2,3-dioxygenase (IDO) catalyses the rate-limiting step in the catabolic pathway of L-Trp. Gene expression analysis has shown upregulation of genes involved in L-Trp catabolism in in vitro models of dengue virus (DENV) infection. To understand the role of IDO during DENV infection, we measured IDO activity in sera from control and DENV-infected patients. We found increased IDO activity, lower levels of L-Trp and higher levels of l-kynurenine in sera from DENV-infected patients during the febrile days of the disease compared with patients with other febrile illnesses and healthy donors. Furthermore, we confirmed upregulation of IDO mRNA expression in response to DENV infection in vitro, using a dendritic cell (DC) model of DENV infection. We found that the antiviral effect of gamma interferon (IFN-gamma) in DENV-infected DCs in vitro was partially dependent on IDO activity. Our results demonstrate that IDO plays an important role in the antiviral effect of IFN-gamma against DENV infection in vitro and suggest that it has a role in the immune response to DENV infections in vivo.

Factor V Leiden and the risk of venous thrombosis, myocardial infarction, and stroke: a case-control study in Venezuela.

The most common genetic defect associated with deep vein thrombosis (DVT) is a mutation in the Factor V gene (G1691A), known as Factor V Leiden (FVL). We investigated the genotypes for FVL in 571 individuals in Venezuela: 208 patients with DVT, 175 patients with acute myocardial infarction, 54 patients with stroke, and 134 control subjects. Our results showed in the population analyzed here that the FVL was associated with a fourfold increase in the risk for DVT (odds ratio, 4.24; 95% confidence interval, 1.35-14.79); particularly, women carriers showed a 6.5-fold increase in the risk for DVT. No relation was observed between the presence of FVL and the risk for acute myocardial infarction or stroke. In conclusion, a clear association between the FVL mutation and DVT was observed in the population analyzed in Venezuela. These results are in agreement with those found in other populations with different ethnic backgrounds.

Inhibition of collagen, and thrombin-induced platelet aggregation by Lansberg's hognose pit viper (Porthidium lansbergii hutmanni) venom.

The Porthidium genus is represented by the P. lansbergii rozei and P. lansbergii hutmanni (Plh) subspecies in Venezuela. The venom components of these have been little studied, probably due to the low incidence of reported accidents, although acute and serious local effects such as invasive edema and disseminated ecchymosis are present during human envenonation. The aim of this work was to characterize the in vitro effects of crude P. l. hutmanni venom, and its fractions, on platelet aggregation triggered by two physiologic agonists: thrombin and collagen. The effects of thrombin and collagen were observed on a platelet-rich plasma (PRP) solution (3 x 10(5) platelets/microL) using serial dilutions of P. l. hutmanni venom (0.625-40 microg). The crude venom was fractionated by anionic exchange chromatography and two peaks obtained. Crude venom and both fractions were highly inhibitory on platelet aggregation mediated by the two agonists. The anti-aggregating dose (AD(50)) for both agonists was determined. PRP collagen-triggered aggregation was most inhibited by the crude venom (AD(50) = 0.67 microg) when compared with PRP thrombin-triggered aggregation (AD(50) = 4.92 microg). Collagen-induced aggregation was more intensely inhibited by venom than thrombin-induced aggregation. In conclusion, to specify the inhibition mechanisms involved for each of the active components in the venom from these subspecies, we must characterize and purify the inhibitors of aggregation from P. l. hutmanni venom, with the purpose of suggesting new pharmacological substances to be incorporated into the therapeutic arsenal to treat hemostatic pathologies related to high levels of platelet aggregation.

Combined deficiency of factor V and factor VIII is due to mutations in either LMAN1 or MCFD2.

Mutations in LMAN1 (ERGIC-53) or MCFD2 cause combined deficiency of factor V and factor VIII (F5F8D). LMAN1 and MCFD2 form a protein complex that functions as a cargo receptor ferrying FV and FVIII from the endoplasmic reticulum to the Golgi. In this study, we analyzed 10 previously reported and 10 new F5F8D families. Mutations in the LMAN1 or MCFD2 genes accounted for 15 of these families, including 3 alleles resulting in no LMAN1 mRNA accumulation. Combined with our previous reports, we have identified LMAN1 or MCFD2 mutations as the causes of F5F8D in 71 of 76 families. Among the 5 families in which no mutations were identified, 3 were due to misdiagnosis, with the remaining 2 likely carrying LMAN1 or MCFD2 mutations that were missed by direct sequencing. Our results suggest that mutations in LMAN1 and MCFD2 may account for all cases of F5F8D. Immunoprecipitation and Western blot analysis detected a low level of LMAN1-MCFD2 complex in lymphoblasts derived from patients with missense mutations in LMAN1 (C475R) or MCFD2 (I136T), suggesting that complete loss of the complex may not be required for clinically significant reduction in FV and FVIII.

Hemophilia treatment in developing countries: products and protocols.

The most important aspect of management of hemophilia is to provide adequate replacement of safe clotting factor concentrates to prevent or treat bleeding episodes. There has been considerable progress in many countries in the developing world with regard to this aspect of care. However, very little data are available in the literature on the types of products being used for factor replacement and the doses being administered for control or treatment of bleeding in different countries. These data are important to document because only then can data from different centers be compared. This article provides data from seven countries: Korea, Malaysia, Thailand, Venezuela, Argentina, Iran, and India. It shows that there is wide variability not only in the types of products used (plasma to recombinant factor concentrates) but also in the doses administered (minimal to very high) for similar indications. Prospective documentation of data on musculoskeletal outcome at these centers and correlation with dose of factor replacement could help identify different models of care. Comparing such data and collating the experience in different countries could be useful for optimizing care and establishing cost-effective models. The combined experience in the developing world in providing hemophilia services should be used to define standards of care that are practical and to set achievable goals.

Dengue virus induces novel changes in gene expression of human umbilical vein endothelial cells.

Endothelial cells are permissive to dengue virus (DV) infection in vitro, although their importance as targets of DV infection in vivo remains a subject of debate. To analyze the virus-host interaction, we studied the effect of DV infection on gene expression in human umbilical vein endothelial cells (HUVECs) by using differential display reverse transcription-PCR (DD-RTPCR), quantitative RT-PCR, and Affymetrix oligonucleotide microarrays. DD identified eight differentially expressed cDNAs, including inhibitor of apoptosis-1, 2'-5' oligoadenylate synthetase (OAS), a 2'-5' OAS-like (OASL) gene, galectin-9, myxovirus protein A (MxA), regulator of G-protein signaling, endothelial and smooth muscle cell-derived neuropilin-like protein, and phospholipid scramblase 1. Microarray analysis of 22,000 human genes confirmed these findings and identified an additional 269 genes that were induced and 126 that were repressed more than fourfold after DV infection. Broad functional responses that were activated included the stress, defense, immune, cell adhesion, wounding, inflammatory, and antiviral pathways. These changes in gene expression were seen after infection of HUVECs with either laboratory-adapted virus or with virus isolated directly from plasma of DV-infected patients. Tumor necrosis factor alpha, OASL, and MxA and h-IAP1 genes were induced within the first 8 to 12 h after infection, suggesting a direct effect of DV infection. These global analyses of DV effects on cellular gene expression identify potentially novel mechanisms involved in dengue disease manifestations such as hemostatic disturbance.

Enfermedad de von Willebrand adquirida como forma de presentación de un mieloma multiple IgA-K / Von Willebrand disease associated with multiple (IgA-K)

Se reporta el caso clínico de un paciente de sexo masculino de 36 años, con historia de diátesis hemorrágica de un año de evolución, sin antecedentes personales o familiares de hemorragia y disminución de los valores de factor VIII:C, factor vWAg y de la actividad Cofactor de Ristocetina. Los estudios realizados con el plasma del paciente y con las fracciones purificadas del mismo, permiten concluir que se trata de una enfermedad de von Willebrand adquirida por acción inhibidora de la paraproteína IgA-K, caracteristica de un mieloma múltiple diagnosticado durante la evaluación de su problema hemorrágico. La acción inhibidora fue dirigida principalmente a la actividad de Cofactor de Ristocetina. El cuadro hemorrágico se correlacionó con los valores elevados de proteínas séricas caracteristicos de su enfermedad base, mejorando en forma temporal con plasmaféresis