Intracellular dynamics of polydnavirus innexin homologues.

Polydnaviruses associated with ichneumonid parasitoid wasps (Ichnoviruses) encode large numbers of genes, often in multigene families. The Ichnovirus Vinnexin gene family, which is expressed in parasitized lepidopteran larvae, encodes homologues of Innexins, the structural components of insect gap junctions. Here, we have examined intracellular behaviours of the Campoletis sonorensis Ichnovirus (CsIV) Vinnexins, alone and in combination with a host Innexin orthologue, Innexin2 (Inx2). QRT-PCR verified that transcription of CsIV vinnexins occurs contemporaneously with inx2, implying co-occurrence of Vinnexin and Inx2 proteins. Confocal microscopy demonstrated that epitope-tagged VinnexinG (VnxG) and VinnexinQ2 (VnxQ2) exhibit similar subcellular localization as Spodoptera frugiperda Inx2 (Sf-Inx2). Surface biotinylation assays verified that all three proteins localize to the cell surface, and cytochalasin B and nocodazole that they rely on actin and microtubule cytoskeletal networks for localization. Immunomicroscopy following co-transfection of constructs indicates extensive co-localization of Vinnexins with each other and Sf-Inx2, and live-cell imaging of mCherry-labelled Inx2 supports that Vinnexins may affect Sf-Inx2 distribution in a Vinnexin-specific fashion. Our findings support that the Vinnexins may disrupt host cell physiology in a protein-specific manner through altering gap junctional intercellular channel communication, as well as indirectly by affecting multicellular junction characteristics.

Functional interactions between polydnavirus and host cellular innexins.

Polydnaviruses are double-stranded DNA viruses associated with some subfamilies of ichneumonoid parasitoid wasps. Polydnavirus virions are delivered during wasp parasitization of a host, and virus gene expression in the host induces alterations of host physiology. Infection of susceptible host caterpillars by the polydnavirus Campoletis sonorensis ichnovirus (CsIV) leads to expression of virus genes, resulting in immune and developmental disruptions. CsIV carries four homologues of insect gap junction genes (innexins) termed vinnexins, which are expressed in multiple tissues of infected caterpillars. Previously, we demonstrated that two of these, VinnexinD and VinnexinG, form functional gap junctions in paired Xenopus oocytes. Here we show that VinnexinQ1 and VinnexinQ2, likewise, form junctions in this heterologous system. Moreover, we demonstrate that the vinnexins interact differentially with the Innexin2 orthologue of an ichnovirus host, Spodoptera frugiperda. Cell pairs coexpressing a vinnexin and Innexin2 or pairs in which one cell expresses a vinnexin and the neighboring cell Innexin2 assemble functional junctions with properties that differ from those of junctions composed of Innexin2 alone. These data suggest that altered gap junctional intercellular communication may underlie certain cellular pathologies associated with ichnovirus infection of caterpillar hosts.

Abnormality of von Willebrand factor in patients with hemoglobin E-beta (0) thalassemia.

The authors have identified six Southeast Asian patients ranging in age from 14 to 21 years with hemoglobin E-beta(0) thalassemia and a coagulopathy involving von Willebrand factor (vWF). These patients had normal or only slightly decreased plasma clotting factor levels. The activated partial thromboplastin time was prolonged in four of the patients. The abnormal feature common to all patients was a qualitative loss of high molecular weight multimers of vWF by crossed immunoelectrophoresis (vWF:CIE). Plasma vWF antigen concentration (vWF:Ag) and ristocetin cofactor activity (vWF:RCo) also were decreased and bleeding time prolonged in three patients. Epistaxis was present in two. No family history of increased bleeding tendency was present in any patient. Coagulation parameters and vWF:CIE were normal in two first-degree relatives without this hemoglobinopathy. vWF abnormalities and clinical manifestations were greatest in those patients with the most severe anemia and hepatosplenomegaly. These six patients appear to have an acquired abnormality of vWF, although they lack the clinical characteristics of acquired von Willebrand disease. While the etiology of this abnormality is unclear, the authors speculate that proteolysis of vWF secondary to extramedullary hematopoiesis or loss through high cardiac output shear stress in these anemic patients may be involved.

Abnormal prothrombin crossed-immunoelectrophoresis in patients with lupus inhibitors.

Prothrombin deficiency has been known to occur in association with lupus inhibitors for over 25 years. We studied 21 patients with lupus inhibitors and found that four of five with prothrombin deficiency and ten of 16 with quantitatively normal prothrombin had abnormal prothrombin crossed-immunoelectrophoresis (CIEP) characterized by material moving slower in the first dimension of electrophoresis than normal prothrombin. In two patients with prothrombin deficiency, all prothrombin measured by quantitative assay and all slow-moving material on CIEP were removed by treatment with Staphylococcal protein A (SPA). These patients had free antibody, which bound to normal plasma prothrombin, forming larger amounts of slow-moving material on CIEP. A third patient with prothrombin deficiency had only partial removal of prothrombin after SPA treatment. Two patients with quantitatively normal prothrombin had all slow-moving material on CIEP and about one fourth of the prothrombin by quantitative assay removed by SPA treatment. There was no correlation among the strength of the inhibitor, the presence of a "cofactor effect," and the prothrombin abnormality. These data suggest that heterogeneous antiprothrombin antibodies, with or without prothrombin deficiency, are present in the majority of patients with lupus inhibitors.

Tympanostomy tubes in children with hemophilia A.

With proper teamwork between the hemotologist and otolaryngologist, children with hemophilia A and otitis media can obtain the benefits of tympanostomy tubes; 90% phenol applied topically to the tympanic membrane is a useful hemostatic agent. The technique may allow the hemophiliac child to undergo myringotomy and insertion of tympanostomy tubes without the use of blood products. There is evidence that the use of such blood products derived from pooled human plasma may be associated with the development of acquired immune deficiency syndrome (AIDS).

Vitamin K deficiency in newborns: a case report in alpha-1-antitrypsin deficiency and a review of factors predisposing to hemorrhage.

A 4-week-old, breast-fed female infant appeared healthy until signs and symptoms of CNS deterioration suddenly occurred. At presentation the infant was found to have a left-sided parietal intracerebral hematoma, markedly prolonged prothrombin time, and partial thromboplastin time, normal platelet count, and jaundice with a total and direct serum bilirubin level of 5.4 mg/dL and 2.6 mg/dL, respectively. Vitamin K1 and fresh frozen plasma returned the prothrombin time and partial thromboplastin time to normal values within 18 hours, suggesting that the infant had severe vitamin K deficiency complicated by intracerebral hemorrhage. Evaluation of the infant's direct hyperbilirubinemia led to the diagnosis of homozygous (pi-type ZZ [PiZZ] ) alpha-1-antitrypsin deficiency. The clinical circumstances predisposing to vitamin K deficiency in newborns and infants are discussed. Based on our observations in this case, we suggest that cholestatic liver disease should be suspected when unexplained vitamin K deficiency occurs in early infancy. The role of vitamin K in hemostasis and the laboratory diagnosis of vitamin K deficiency are discussed as they apply to the evaluation of hemorrhage in newborns and infants.

Hemophilia B. Case study and intervention plan.

Persistent bleeding from the circumcision site or umbilicus of a newborn male should alert the neonatal nurse to the possibility of hemophilia. Treatment of hemophilia B requires immediate medical and nursing intervention as well as long-term follow-up so that psychosocial, developmental, and physiological needs of the infant and family are met. Most important, treatment requires an organized team approach. Information to assist the nurse in the treatment of the infant and family is presented.

Factor V deficiency in Philadelphia-positive chronic myelogenous leukemia.

Factor V deficiency has been identified in 8 of 8 patients 7--20 yr of age, with Philadelphia-positive (Ph1+) chronic myelogenous leukemia (CML). In these 8 patients, factor V deficiency was not due to hepatic dysfunction, factor V inhibitors, or disseminated intravascular coagulation. In 3 patients, factor V activity rose 10%--12% (0.10--0.12 U/ml) after the infusion of 28--31 ml/kg body weight of fresh frozen plasma (FFP). The rise persisted less than 14 hr. The mean measured postinfusion rise in factor V was 18% of the expected rise calculated from the volume of FFP infused in the patients' plasma volume. In 4 patients, a small transient rise in factor V activity occurred after splenectomy or plateletpheresis. Factor V deficiency was completely corrected after a marked reduction in bone marrow cellularity in 2 patients with Ph1+ CML treated with extensive chemotherapy, total body irradiation, and bone marrow transplantation. Factor V deficiency was retrospectively observed in 6 of 20 patients, ages 20--80 yr, with Ph1+ CML and 3 of 6 patients with other myeloproliferative disorders. The factor V deficiency appears to be associated with the large myeloid-megakaryocytic cell mass characteristic of CML and other myeloproliferative disorders.

Thrombotic and hemorrhagic strokes complicating early therapy for childhood acute lymphoblastic leukemia.

Sudden cerebrovascular insults occurred during or immediately following remission induction therapy in 4 children with acute lymphoblastic leukemia. In 3, cerebral infarction was due to thrombosis. In the fourth, an intracerebral hematoma developed representing either frank hemorrhaging or a hemorrhagic infarction. None of the patients had central nervous system leukemia or extreme leukocytosis at the time of diagnosis. Symptoms were obtundation, hemiparesis, seizures, and headache. The induction chemotherapy included L-asparaginase which causes deficiencies of antithrombin, plasminogen, fibrinogen, and factors IX and XI. These hemostatic abnormalities may explain the thromboses and bleeding observed in these children.

Plasminogen and antithrombin III deficiencies in the childhood nephrotic syndrome associated with plasminogenuria and antithrombinuria.

Three of four patients with the childhood nephrotic syndrome were found to have low plasma plasminogen concentrations; all four had low plasma antithrombin III concentrations. In the two patients who were tested, urinary concentrations of these proteins exceeded the plasma concentrations. As the urinary losses of plasminogen and antithrombin III decreased over the course of illness, the plasma concentrations of antithrombin III and plasminogen rose. One patient had multiple thromboembolic episodes. We conclude the deficiencies of antithrombin III and plasminogen, probably secondary to urinary excretion of these proteins, may contribute to the thrombotic diathesis associated with nephrotic syndrome.