Tissue-type plasminogen activator, plasminogen activator inhibitor, and histidine-rich glycoproteins in stressed human newborns.

Normal newborns have reduced levels of tissue-type plasminogen activator (tPA). Stressed newborns have an increased prevalence of thrombotic diseases. An impaired release of tPA and/or increased plasminogen activator inhibitor (PAI) is associated with thrombotic risk in the adult patient. The purpose of this study was to assay the plasma levels of tPA, PAI, histidine-rich glycoprotein (HRG), and other fibrinolytic proteins in 15 severely stressed newborns. The stressed babies showed significantly higher (p less than .001) levels of tPA antigen compared with normal newborns. Also, PAI activity and PAI-1 antigen levels were increased. Levels of both HRG and plasminogen were higher in the stressed group but the ratio of HRG to plasminogen was the same as that in the normal control newborns (1:3), suggesting an insignificant effect of HRG. D-dimers were significantly elevated in the stressed newborns. However, 8 patients died and 4 of these were found to have massive thrombotic disease on autopsy. These results show that the newborn when stressed will increase tPA levels and activate the lytic system. However, the activity is suboptimal inasmuch as PAI activity did not decrease and thrombotic disease was observed.

A variant form of thrombasthenia.

We encountered two siblings with abnormal bruising since infancy. Studies revealed functional platelet defects characterized by a lack of platelet aggregation and adenosine triphosphate release on exposure to adenosine diphosphate and collagen as well as variable responses with ristocetin (at concentrations of less than or equal to 1.25 g/L) and arachidonic acid. In addition, little or no platelet aggregation was observed after exposure to hexadimethrine bromide (Polybrene), the calcium ionophore A23187, and the thromboxane/endoperoxide analogue U46619. The membrane proteins IIIa and Ib were present, as determined with monoclonal antibody testing, and no platelet-associated IgG was found. Platelet analysis with routine electron microscopy and ultrastructural cytochemistry revealed normal morphologic features and no deficiencies in the number of alpha granules dense bodies and other organelles. The platelet abnormality may represent a new variant of thrombasthenia.

Mojave rattlesnake (Crotalus scutulatus scutulatus) venom: in vitro effect on platelets, fibrinolysis, and fibrinogen clotting.

Rattlesnake envenomation commonly produce defects in the hemostatic mechanism. However, Mojave rattlesnake (Crotalus scutulatus scutulatus) envenomation has been reported not to cause a systemic bleeding diathesis. In this study, whole venom from the Mojave rattlesnake was tested in vitro for fibrinogen clotting activity, ability to induce platelet aggregation, and for fibrinolytic activity. The Mojave venom caused no fibrinogen clotting and it displayed very weak ability to cause platelet aggregation and fibrinolytic activity. These in vitro studies support the clinical observation that Mojave envenomation does not cause a coagulopathy.

Histidine-rich glycoprotein and plasminogen plasma levels in term and preterm newborns.

The newborn's fibrinolytic system is not the same as that in the adult. Hypoplasminogenemia with normal (adult) levels of alpha 2-plasmin inhibitor and plasminogen activator inhibitor are characteristic of the newborn's lytic system. This combination suggests that the newborn may have an impaired lytic system that may explain, in part, the thrombotic events that are frequently observed. Histidine-rich glycoprotein (HRG), another fibrinolytic inhibitor, retards fibrinolysis by interfering with plasminogen's binding to fibrin. Levels of HRG have been reported to be reduced in term newborns. This finding has not been studied recently and to our knowledge, there are no reports of HRG levels in premature infants. The purpose of this study was to measure the plasma levels of HRG and plasminogen in three groups of patients: normal adults (n = 48), normal term newborns (n = 43), and normal premature newborns (n = 18). The protein levels were determined by electroimmunoassay. Cross-immunoelectrophoresis was also performed for HRG. Cord blood was employed for obtaining newborn citrated plasma. The newborns had significantly lower plasminogen and HRG levels when compared with those of the adults. Also, the HRG levels of the premature newborns were lower than those of the term newborns. In conclusion, the newborns had lower levels of HRG than adults, with premature newborns having the lowest levels. This may allow for more plasminogen to be available for fibrin binding even though newborns have hypoplasminogenemia.

Effects of chronic beta-carotene supplementation on vitamin K status in adults.

Plasma vitamin K concentrations and prothrombin coagulation activity were determined in 26 normal adults who had received daily beta-carotene supplementation (0, 15, 30, or 60 mg) for six months. Neither plasma vitamin K nor coagulation activity were significantly decreased at any supplementation level. Thus, chronic beta-carotene supplementation, even at high daily doses, is not expected to result in clinical vitamin K deficiency. The data suggest separate mechanisms for intestinal absorption of beta-carotene and vitamin K.

Newborn's fibrinolytic mechanism: components and plasmin generation.

Plasminogen activity and antigen, tissue-type plasminogen activator (tPA) activity and antigen, plasminogen activator inhibitor (PAI) activity, and plasmin generation rates were determined in 32 normal newborn plasmas and 25 normal adult plasmas. The newborns showed reduced levels of plasminogen activity and antigen and tPA antigen, and activity, normal levels of PAI activity, and slower plasmin generation rates. The slower generation was shown to be due to the hypoplasminogenemia. The in vitro plasmin generation studies also showed that the newborn needed 11 times the usual concentration of urokinase and 5 times the usual concentration of tPA to achieve the minimal activation rate of the adult.

Factor VIII: von Willebrand factor patterns in the plasma of patients with pre-eclampsia.

Elevation of the factor VIII protein to coagulant ratio previously has been reported to predict the severity of pre-eclampsia. Abnormal levels and patterns of factor VIII: von Willebrand factor (VIII/vWF) have been reported in thrombotic thrombocytopenia purpura (TTP). Severe pre-eclampsia shares many features with this syndrome. Nine primigravid patients with pre-eclampsia were evaluated by assays for factor VIII/vWF protein and coagulant activity and were compared to nine normal primigravid (controls). The patients and controls were indistinguishable by factor VIII antigen/coagulant activity ratios. Pre-eclamptic patients also had unremarkable factor VIII patterns on crossed immunoelectrophoresis. The evaluation of factor VIII/vWF multimeric patterns showed four patients with abnormal patterns in the pre-eclamptic patients and three abnormal patterns in the controls. These patterns were not analogous to the factor VIII abnormalities found in TTP.

Danazol-induced factor VIII and IX bypassing activity in hemophiliacs.

Danazol, a synthetic androgen reported to increase factor VIII and IX activity levels, was given to 6 hemophiliacs. With danazol therapy (600 mg/da) the APTTs shortened by 30-45% of pre-treatment times. However, the activity levels of the deficient factors did not increase significantly nor consistently with the APTT change. The prothrombin times and activity levels of factors XI and XII also did not change during the study period. Addition of plasma from danazol-treated patients to plasma with a known factor VIII inhibitor and to plasma from an untreated severe hemophilia A patient caused a similar shortening of the respective APTTs. Absorption of the danazol plasma with precipitating antibody against factor VIII and IX did not remove the APTT correcting principal. The data suggest that danazol may cause the de novo appearance of an intrinsic coagulation pathway activator having factor VIII and IX bypassing activity.

Treatment of hemophilic arthritis with D-penicillamine: a preliminary report.

Current medical management programs for established joint diseases in hemophiliacs are unsatisfactory and do not modify the eventual outcome. D-penicillamine, a drug effective in the proliferative synovitis of rheumatoid arthritis, was evaluated in a rabbit model of hemarthroses-induced arthritis and in four hemophiliacs with chronic synovitis. The animals had intra-articular injections of citrate (left knees) and autologous citrated whole blood (right knees). Eight weeks later, the rabbits were divided into two groups: no treatment and D-penicillamine (50 mg/kg/day, IM) until sacrificed at 6 months. The saline-injected joints showed no inflammation and no iron deposition. The blood-injected knees showed iron deposition in both groups, the D-penicillamine animals had marked suppression of chronic inflammation. Of the four patients treated, three had clinical responses (reduction in synovial thickness, reduction in number of bleeds in the affected joint). One patient, who did not respond, developed mild-moderate proteinuria. Those patients who responded received between 5.3 and 7.1 mg/kg/day of the drug. Mild abnormalities in platelet aggregation were seen in the responders. This preliminary study suggests that D-penicillamine is beneficial in the chronic synovitis/arthritis induced by hemarthroses. Further trials are recommended.

Effect of danazol on coagulation parameters and bleeding in hemophilia.

Danazol was given orally at a dose of 600 mg/day to six hemophiliacs for eight to 14 weeks. All patients showed a significant decrease in activated partial thromboplastin time (APTT) beginning with the first measurement (two weeks) and persisting until use of the drug was discontinued. However, a corresponding increase in the deficient factor activity could not be consistently demonstrated. Despite the shortened APTT, bleeding episodes continued in the severe hemophiliacs and the patient with Christmas disease. In four patients, bleeding appeared to increase in severity or change in pattern, and in two cases the bleeding manifestations did not respond to usual factor infusions but responded to discontinuation of the drug therapy and further factor replacement. Euglobulin lysis times were measured in five patients (one hemophiliac and four with nonhemophilic conditions) who were receiving danazol. The lysis times were markedly shortened. Increased fibrinolytic activity may be responsible for the increased bleeding manifestations in danazol-treated hemophiliacs.

Prothrombin antigen and coagulant activity in patients with liver disease.

Plasma levels of prothrombin immunoreactive protein (factor II antigen) (II-Ag) and coagulant activity (II-CA) were determined in eight patients with acute hepatitis and in 29 patients with chronic liver disease (cirrhosis). The II-CA was reduced in 23 (62%), II-Ag in 17 (46%), and both were reduced in 13 (36%) of the cases. A disproportionate reduction was noted in 21 (57%); ie, there was more II-Ag found in comparison to the corresponding level of II-Ca. Ninety-six percent (23) of 24 patients with moderate to severe hepatocellular disease showed reduced II-CA levels; 63% (15) showed reduced II-Ag levels, with a disproportionate reduction in II-CA in 67% (16). These data suggest that reduced synthesis as well as impaired carboxylation of prothrombin precursor protein are factors contributing to the coagulopathy in patients with moderate to severe liver disease and that measurement of circulating levels of II-Ag may provide an excellent indication of hepatic synthetic capacity.

Envenomation by the northern blacktail rattlesnake (Crotalus molossus molossus): report of two cases and the in vitro effects of the venom on fibrinolysis and platelet aggregation.

In two cases of human envenomation by the northern blacktail rattlesnake (Crotalus molossus molossus) there was marked swelling and ecchymosis of the bitten extremity and thrombocytopenia and, in one case, hypofibrinogenemia. Treatment consisted of i.v. antivenin, crystalloid solution, fresh frozen plasma and cryoprecipitates, with recovery in each case. In vitro studies showed that the venom had fibrinolytic and platelet aggregating properties; a coagulant effect, although present, was much less marked.

Aortic thrombosis in a neonate: failure of urokinase thrombolytic therapy.

Complete aortic occlusion at L2-L3 occurred in an 11-day-old male with hypernatremic dehydration. Attempted thrombolytic therapy using intraarterial urokinase was unsuccessful in inducing either a systemic hyperfibrinolytic state or lysis of the clot. The infant's plasma plasminogen level was low (50-75% of adult levels) and neither fresh frozen plasma nor cryoprecipitate infusion provided adequate plasminogen replacement. Thrombolytic therapy failure was due in part to inadequate generation of plasmin. Alternative means of lytic therapy will need to be devised for this age group.

Transmission of Plasmodium vivax from Vietnam by four different anophelines.

Infections of the SV-I strain of Plasmodium vivax from Vietnam were transmitted via the bites of infected Anopheles stephensi, An. maculatus, and An. balabacensis balabacensis mosquitoes. Infected salivary glands were also found in An. freeborni mosquitoes. In 18 successful transmissions, prepatent periods ranged from 10--17 days. Four black volunteers failed to develop infections even though they were fed upon by heavily infected An. maculatus and An. b. balabacensis mosquitoes.