Nervous regulation of factor-VIII levels in man

Bleeding disorders: A common cause of menorrhagia in adolescents

OBJECTIVE

To determine the frequency of underlying bleeding disorders in adolescents with menorrhagia.

STUDY DESIGN

We retrospectively reviewed the charts of all girls, aged 10 to 19 years, who presented to our children's hospital for inpatient or outpatient evaluation of menorrhagia between January 1990 and November 1998.

RESULTS

At presentation, 9 of the 71 girls (13%) had thrombocytopenia (platelet count <150,000/microL; range, 5000-106,000/microL). The most common causes for thrombocytopenia were immune thrombocytopenic purpura (n = 5) and myelosuppression caused by chemotherapy (n = 2). Of 14 girls who underwent a more detailed hemostatic evaluation, 8 were given a diagnosis of a hereditary coagulation disorder: 6 had platelet function defects and 2 had type 1 von Willebrand disease. Excessive menstrual bleeding commonly results in anemia. One half of the total group had anemia (hemoglobin <12.0 g/dL). Seven girls (10%) had potentially life-threatening anemia (hemoglobin <5.0 g/dL).

CONCLUSIONS

Acquired and congenital bleeding disorders are common causes of menorrhagia in adolescent girls. Severe anemia is a frequent complication of menorrhagia. We recommend that adolescents without thrombocytopenia who present with menorrhagia receive a comprehensive hemostatic evaluation, including testing for von Willebrand disease and platelet function defects.

Normal homeostasis of fibrinolysis in nephrogenic diabetes insipidus in spite of defective V2- receptor-mediated responses of tissue plasminogen activator release

Three patients with congenital, nephrogenic diabetes insipidus (NDI) from two unrelated families were tested for haemostatic and fibrinolytic responses to DDAVP infusion and venous occlusion. None of the three patients showed a response of factor VIII:C, vWF:Ag or t-PA to DDAVP, a V2-agonist. However, the baseline levels of these factors in the patients' plasma were normal and during venous occlusion a rise in t-PA antigen and t-PA activity was observed in all patients. One patient showed a definite response of the t-PA antigen level to exercise. It is concluded that (extrarenal) V2-receptor-mediated responses are absent in these patients, but that baseline homeostasis and the response to venous occlusion and physical exertion are intact. Presumably, these depend on other mechanisms. This observation denies a central role for vasopressin receptors in the on-demand regulation of clotting and clot dissolving properties of the blood.

Factor VIII R:Ag as a prognostic parameter in intracranial haemorrhage

Factor VIII R:Ag was measured serially in 42 patients who had intracranial haemorrhage. It was found that the factor decreased or remained static in the 24 patients who improved (p less than 0.025), while it increased in the 18 who died (p less than 0.0005). It is suggested that this factor can be used as a prognostic parameter to predict the outcome after intracranial haemorrhage.

The effect of calcium on the secretion of factor VIII-related antigen by cultured human endothelial cells

Cultured human endothelial cells derived from the umbilical cord vein are able to release factor VIII-related antigen into the culture medium. The experiments described in this paper show the presence of two pathways for the secretion of factor VIII-related antigen from endothelial cells. There is a basal release of this antigen, independent of the presence of extracellular calcium ions. This release can be inhibited by cycloheximide and is therefore directly related to de novo protein synthesis. Besides this basal release, there is an extra release of factor VIII-related antigen that can be stimulated by thrombin, the Ca2+-ionophore A23187 or phorbol myristate acetate. As demonstrated by immunofluorescence, the stimulus-inducible release originates from storage granules in the cells. This stimulus-inducible release is dependent on extracellular Ca2+ but independent of intracellular cAMP.

Factor VIII-related antigen and procoagulant activity in manic-depressive patients

Factor VIII-related antigen (VIIIR:AG) and procoagulant activity (VIII:C) were measured at weekly intervals in 11 manic-depressive patients during their hospital stay. There were significant correlations between VIII:C (P less than 0.02), VIIIR:AG (P less than 0.05) and the number of hospital admissions over a 10-year period. The patients' VIIIR:AG showed a wider range of results as compared to a control group (P less than 0.01). The age of onset of the disease (but not the age of the patient) was related to VIIIR:AG (P less than 0.02).

Effects of growth hormone, glucose and insulin on the factor VIII complex

The relationship of growth hormone (GH) to the factor VIII complex (VIIIC, VIIIRAg and VIIIRRCo) was investigated. No correlation between basal levels of GH and factor VIII assays was found in 23 subjects. No significant change in factor VIII assays was observed after GH suppression by oral glucose or bromocriptine. After insulin-induced hypoglycaemic all three factor VIII assays rose and fell in parallel with GH. However, after exercise the rise in VIIIC and VIIIRAg preceded the rise in GH; and no changes in factor VIII assays were observed after administration of thyrotrophin releasing hormone (TRH) (releasing endogenous GH) or exogenous GH. These findings do not support a role for GH in the regulation of plasma levels of VIIIC, VIIIRAg or VIIIRRCo.

Postoperative changes in coagulation and fibrinolysis independent of neurogenic stimuli and adrenal hormones

Postoperative changes in various haemostatic parameters (capillary bleeding time, platelet count, fibrinogen, fibrinmonomers, prothrombin, antithrombin III, factor VIII procoagulant, factor VIII antigen, euglobulin clot lysis time, streptokinase lysis time, fibrinogen related antigens, alpha 1-antitrypsin and alpha 2-macroglobulin) plasma glucose and cortisol were studied in 12 female patients undergoing elective abdominal hysterectomy during either general anaesthesia or epidural analgesia (T4-S5). General anaesthesia and epidural analgesia (T4-S5). General anaesthesia and epidural analgesia on their own had only negligible influence on haemostatic parameters. Hysterectomy during general anaesthesia caused activation of coagulation and fibrinolysis, followed by depression of fibrinolysis. Epidural analgesia prevented the cortisol and glucose response to surgery, but did not influence the coagulation and fibrinolytic response to surgery, except for an inhibition of the postoperative increase in factor VIII antigen. It is concluded that postoperative changes in the coagulation and fibrinolytic systems are mediated by factors other than neurogenic stimuli and adrenal hormones.

New methods in coagulation

Recent advances in the elucidation of the molecular biochemistry of the coagulation proteins have provided the foundation for the development of synthetic substrates. These substrates are oligopeptide with either a chromophore or fluorophore group attached to the C-terminal end. They may be used in the laboratory to assay for a number of the serine proteases involved in either coagulation or fibrinolysis. Also, by suitably modifying the assay system, the various inhibitors can be quantitated. These substrates promise to revolutionize the coagulation laboratory allowing for more precise quantitation of trace enzymes and also improved standardization and precision of coagulation assays. In addition to these substrates, the introduction of a number of immunologic procedures into the diagnostic laboratory have been of major importance in elucidating the heterogeneity of hereditary coagulation defects. By correlating the immunologic assays, coagulation assays and clinical picture, a number of subgroups of hereditary deficiencies have been identified. Also, the immunologic assays have provided a means for identifying the carrier state of hemophilia A and have significantly contributed to the improved diagnosis of von Willebrand's disease. The use of ristocetin cofactor assays, when used in conjunction with the Factor VIII antigens, have enable the laboratory to more accurately diagnose the majority of patients with von Willebrand's disease. Ristocetin cofactor may be assayed utilizing either formalin fixed or washed platelets and recently a snake venom has been introduced to assay for this particular aspect of the Factor VIII complex. Platelet specific proteins (i.e., platelet factor 4 and beta-thromboglobulin) may be assayed utilizing either radioimmunoassays or in the case of platelet factor 4 modified coagulation assays. These proteins provide evidence of in vivo platelet activation and hopefully may, in the future, be correlated with platelet kinetics.

Increase in coagulation factor VIII activity in man following acute hypoglycaemia: mediation via an adrenergic mechanism

Coagulation factor VIII activity has been assayed in nine normal volunteers before and after acute hypoglycaemia. In all subjects there was a rise in activity with a mean increment of 96%. Control studies using saline failed to demonstrate any change. In four subjects with pre-ganglionic sympathetctomy no increase in activity was observed. In the normal subjects the increase was blocked by propranolol but not by metoprolol, indicating mediation via beta2 receptors.

Problems in the detection of carriers of hemophilia A: the influence of stress and thrombin

After exposure to stress, factor VIII coagulant activity and factor VIII antigen were determined in healthy volunteers for about 3 days. Three out of four volunteers at different time showed results resembling a carrier state. In vitro incubation of plasma with thrombin in decreasing concentrations showed increased factor VIII coagulant activity, although no fibrin clot or fibrin monomers were formed. The concentration of factor VIII antigen remained constant. The action of thrombin can explain the misclassification of known carriers.

Mechanism of plasminogen activator and factor VIII increase after vasoactive drugs

Adrenaline, nicotinic acid (NA), vasopressin (LVP) and other drugs affecting vascular motility are known to increase plasminogen activator (PA) and factor-VIII plasma levels in man. To evaluate the hypothesis that NA, LVP and adrenaline release PA from the endothelial cells of the vessel wall through their common effect on vascular motility, PA has been characterized by means of a histochemical technique on vein biopsies obtained from human volunteers after infusion of the compounds. Furthermore, the effect of single and repeated administration has been compared in order to investigate whether the pattern of PA and factor-VIII variations in plasma is similar with the three drugs. There was no major difference in the PA content of the veins following the marked and sustained increase of the corresponding plasma activities. A simple explanation is that the intensity and duration of the stimulus may not be sufficient to deplete the large stores of the vessel walls. The magnitude, time course and duration of the plasmatic response after single and repeated infusions was on the whole different and peculiar for each drug. A derivative of LVP which is free of vasoactive actions was more effective than LVP in inducing the responses, which could also be elicited in two anephric subjects. These findings suggest that vasoactivity is unlikely to provide the clue to a common pathway for the fibrinolysis and coagulation response after the compounds, and support the existence of different specific receptors.