A haemorrhagic platelet disorder associated with altered stimulus-response coupling and abnormal membrane phospholipid composition

Haemorrhagic diatheses due to platelet function defects are a heterogenous and poorly understood group of conditions. We report the investigation of a female with a lifelong history of epistaxes, haemarthroses, menorrhagia and persistent iron-deficiency anaemia. Although platelet numbers and morphology were normal, platelet function was abnormal both in vivo and in vitro. Skin bleeding time was prolonged and aggregation thresholds in platelet-rich plasma to a variety of weak and strong agonists were increased. Platelet granule contents were normal and membrane glycoproteins GpIb and GpIIIa were present in normal amounts. Polyphosphoinositide metabolism and phosphatidic acid generation were diminished in thrombin-stimulated platelets, as was phosphorylation of the 47 kD substrate for protein kinase C and the 20 kD protein myosin light chain kinase, indicating impaired generation of the intracellular second messengers diacylglycerol and inositol trisphosphate due to diminished stimulated phospholipase C activity. Although intracellular free calcium, calmodulin activity and basal cAMP concentrations were normal, washed platelets showed increased cAMP accumulation following stimulation with prostaglandin E1 and forskolin. Platelet membrane lipid analysis revealed a reduction in plasmalogen phosphatidylethanolamine content. It is suggested that the membrane phospholipid abnormalities cause the abnormal platelet reactivity by interfering with signal transduction from platelet receptor, via intermediary G proteins, to phospholipase C and adenylate cylase. The bleeding tendency is likely to be a consequence of the altered stimulus-response coupling.

Changes in haematological indices, blood viscosity and inhibitors of coagulation during treatment of endometriosis with danazol

The effects of treatment with danazol (600 mg daily) on haemostatic and haematological function were investigated in 18 pre-menopausal women with endometriosis. Blood samples were taken at 2 pre-treatment visits, at 6, 12 and 24 weeks on treatment, and at 6 weeks after discontinuation of the drug. Haemoglobin, red cell count, haematocrit and platelet count all rose significantly during treatment with danazol (p < 0.01 vs. baseline). Plasma fibrinogen levels fell significantly (p < 0.01), while whole blood viscosity increased during treatment and remained significantly elevated at follow-up. The prothrombin time shortened, but remained within normal limits, and there were no significant changes in factor VII:C, VIIa, or fibrinopeptide A. No significant changes were found in platelet function. Plasma B-beta 15-42 increased significantly. Functional levels of protein C, protein S, and antithrombin III, all rose significantly, above the normal range, while C4b-binding protein levels fell. We conclude that the observed changes in coagulation inhibitors and fibrinolytic activity may be considered beneficial in the context of venous thromboembolism. The rheological effects, however, indicate a degree of caution in the use of the drug in individuals considered to be at risk from arterial cardiovascular disease.

A cross-over pharmacokinetic and thrombogenicity study of a prothrombin complex concentrate and a purified factor IX concentrate

A prospective cross-over study was carried out on 19 patients with haemophilia B. comparing the pharmacokinetics of a purified factor IX concentrate prepared by metal chelate affinity chromatography (9MC) with a conventional three-factor prothrombin complex concentrate (9A). The highly purified factor IX concentrate was shown to have a half-life comparable to the PCC; the in vivo recovery of the purified concentrate was significantly greater than that of the complex (P < 0.01). The 20% change in the value of the International Standard for Factor IX Concentrate, introduced in 1988, might have been expected to lower the recovery values. However, the in vivo recovery for both concentrates was somewhat higher than reported previously, particularly in the older literature. In nine patients, serial assays for fibrinopeptide A, prothrombin fragment F1+2 and thrombin-antithrombin complexes (TAT) were performed to assess the potential thrombogenicity of the two concentrates. Evidence was obtained that there was significantly less activation of coagulation following administration of purified factor IX (9MC), as compared to the activation that occurred after the PCC.

Increased soluble IL-2 receptor levels in HCV-infected haemophiliacs: a possible indicator of liver disease severity

We have measured sIL-2R in 60 haemophiliacs and 20 male control subjects. Haemophiliacs were grouped according to their HIV/HCV antibody status. Group 1 (n = 20) comprised HIV + ve/HCV + ve, group 2 (n = 27) HIV - ve/HCV + ve and group 3 (n = 13) HIV - ve/HCV - ve. Group 4 comprised the normal control subjects. We also examined, retrospectively, the relationship between the severity of chronic liver disease, assessed histologically, and sIL-2R levels in selected patients. There was no significant difference between sIL-2R levels of the group 1 and group 2 patients, and the levels for both were significantly greater than those of either the group 3 patients or the control subjects. sIL-2 levels were also higher in selected patients with cirrhosis than in those with chronic active hepatitis (CAH) or chronic persistent hepatitis (CPH). We conclude that in haemophiliacs, chronic HCV-related liver disease is associated with increased plasma levels of sIL-2R and that the degree of elevation may reflect the severity of the associated chronic liver disease.

Protein C, antithrombin III and plasminogen: effect of age, sex and blood group

We conducted a cross-sectional study of antithrombin III (ATIII), protein C (PC) and plasminogen (Plg) concentrations in a population of healthy plasma donors in the Trent Region. The distribution of values for protein C was log normal whereas for ATIII and Plg the distributions were positively skewed and differed significantly from normal and log normal. Males had higher antithrombin III concentrations (mean 1.10 iu/ml, range 0.72-1.65) than females (mean 1.07 iu/ml, range 0.75-1.69) (P = 0.001) and levels increased with age in women. Younger women aged 25-34 had significantly lower plasma concentrations of ATIII compared to males of similar age. For protein C, concentrations were higher in males (mean 1.07 u/ml, range 0.37-2.11) than in females (mean 1.01 u/ml, range 0.59-1.61) (P < 0.001) and levels increased with age in both sexes P < 0.001). In women, a novel difference in protein C concentration between ABO blood groups was noted. There was no significant difference in plasminogen concentration between males and females, and in women plasminogen decreased with age (r = -0.205, P < 0.001). We conclude that these variations in ATIII and protein C with age and sex are important considerations in the determination of reference ranges for these proteins.

Factor VIII gene rearrangements in patients with severe haemophilia A

Sequences within intron 22 of the factor VIII (FVIII) gene have been implicated in the cause of haemophilia in almost 50% of severely affected patients. The changes result from intrachromosomal rearrangements of the tip of the long arm of the X chromosome, one break-point being within intron 22 of the FVIII gene. The rearrangements can be identified by Southern blot and we report use of this procedure to detect rearrangements in 11 of 23 unrelated families with severe haemophilia A. Of 22 patients studied, none of the 10 with the gene rearrangement had at any time developed inhibitors to FVIII, compared with 7 of 12 lacking the rearrangement.

A comparison of the allelic frequencies of ten DNA polymorphisms associated with factor VIII and factor IX genes in Thai and Western European populations

The frequency of five factor VIII gene intragenic and linked DNA polymorphisms and five factor IX gene intragenic polymorphisms was studied in Thai females. The polymorphisms in the FVIII gene were detected by restriction enzymes BclI, XbaI, BglI and at linked loci DX13 (DXS15) and St14 (DXS52) by BglII and TaqI, respectively, and in the FIX gene by MseI, DdeI, XmnI, TaqI and HhaI. With the exception of the BglI restriction fragment length polymorphism (RFLP), which is absent in Thais, factor VIII polymorphism frequencies were similar in Thais and Caucasians. Combined use of XbaI and TaqI/St14 resulted in a heterozygosity rate of greater than 90% in Thai females. For FIX, the recently described MseI RFLP in the 5' flanking region was the most informative polymorphism in Thais, 43% of females being heterozygous. The other four polymorphisms added little to the overall heterozygosity rate. The appropriate polymorphisms were used to track defective factor VIII and IX genes through 22 Thai pedigrees with haemophilia to enable carrier status to be assigned to female family members. The information obtained during this study will form the basis for carrier detection and prenatal diagnosis of haemophilia A and B by DNA polymorphism analysis in Thailand.

Thromboxane and prostacyclin synthesis in experimental pancreas transplantation. Changes in parenchymal and vascular prostanoids

The principal causes of failure of a pancreas transplant are rejection and vascular thrombosis. There is an unusually high attrition rate for pancreas transplants, but study models have been difficult to develop. In a rat model that allows study of acute rejection to the exclusion of nonspecific effects of transplant surgery on the pancreas, in vitro synthesis of prostacyclin (PGI2) and thromboxane A2 (TXA2) by transplanted pancreas and the blood vessels transplanted with it was measured using an RIA for their stable hydrolysis products 6-keto-prostaglandin F1 alpha and thromboxane B2 (TXB2). TXB2 synthesis was significantly greater in allotransplanted pancreas than isotransplanted pancreas from the 5th day after transplantation. Rejection was complete in the allografted group 7-9 days after transplantation. 6-Keto-prostaglandin F1 alpha synthesis was similar in the pancreas for both allografts and isografts. Similar changes were seen in aorta, celiac artery, superior mesenteric artery, and portal vein transplanted with the pancreas. In the transplanted aorta, TXB2 was significantly greater in the allograft group from the third posttransplant day. A group of CsA-treated allografts sampled after 9 days had transplanted pancreatic parenchymal and vascular prostanoid synthesis in the isograft range. The changes in PGI2 and TXA2 synthesis that accompany cellular rejection may mediate vascular failure in rejecting pancreas transplants, and changes in PGI2 and TXA2 synthesis in blood vessels transplanted with the pancreas could promote early vascular thrombosis.

Chronic hepatitis in haemophilia

Chronic hepatitis affects almost all haemophiliacs treated with non-virally inactivated clotting factor concentrates. The virus responsible is hepatitis C (HCV) and most patients have non-neutralising antibodies with circulating virus. Although the majority also have evidence of past infection with hepatitis B, less than 5% are chronic carriers of HBsAg. Chronic hepatitis C can be associated with severe and progressive liver disease but the development of complications is slow. Treatment with recombinant interferon alpha given subcutaneously normalises the liver function in 50% of patients, but 50% of responders relapse on stopping treatment. Liver transplantation is successful in patients with advanced liver disease and it offers the added advantage of phenotypic cure of the haemophilic state.

Reduced tissue type plasminogen activator activity of the gastroduodenal mucosa in peptic ulcer disease

The gastroduodenal mucosa has a rich blood supply. An active fibrinolytic system is presumably required to maintain vascular patency, and impairment may result in reduced blood flow, focal tissue necrosis, and peptic ulcerogenesis. Tissue type and urokinase type plasminogen activator activity (expressed as mIU/mg protein) and plasminogen activator inhibitor type-1 antigen were assayed in homogenates of gastric and duodenal biopsy specimens taken from patients with: normal endoscopy (controls) (n = 14); active duodenal ulcer (n = 21); healed duodenal ulcer (n = 12); and active benign gastric ulcer (n = 15). In controls mean duodenal tissue type plasminogen activator activity was 4110 and urokinase type plasminogen activator activity 150; gastric tissue type plasminogen activator was 2760 and urokinase type plasminogen activator 170; plasminogen activator inhibitor type-1 was generally undetectable. At the edge of active duodenal ulcers tissue type plasminogen activator was considerably reduced, 2220 (p < 0.001) whereas urokinase type plasminogen activator was raised, 290 (p < 0.01). At the edge of active benign gastric ulcers tissue type plasminogen activator was substantially reduced, 1160 (p < 0.001) but urokinase type plasminogen activator was unchanged. At the scar of healed duodenal ulcers tissue type plasminogen activator was slightly reduced, 3290, but urokinase type plasminogen activator was increased, 308 (p < 0.05). H2 receptor antagonist treatment had little effect on tissue type or urokinase type plasminogen activator activity. Plasminogen activator inhibitor type-1 was increased at the edge of active ulcers (p < 0.05) especially when tissue type plasminogen activity was low (r = -0.61, p < 0.05). These findings are consistent with the hypothesis that impaired fibrinolytic activity may be implicated in peptic ulcerogenesis.

Identity of viridans streptococci isolated from cases of infective endocarditis

The oral streptococci have undergone considerable taxonomic revision in recent years but there is still little information concerning associations between the newly defined species and disease. This study examined the identities of 47 strains of oral streptococci collected from 42 confirmed cases of infective endocarditis. By means of recently described physiological schemes, the most common species identified were Streptococcus sanguis sensu stricto (31.9%), S. oralis (29.8%) and S. gordonii (12.7%). Other related species including S. mitis and "S. parasanguis" were less common. This indicates that attention should be focused on S. sanguis sensu stricto and S. oralis when considering possible pathogenic mechanisms involved in viridans streptococcal endocarditis.

Reduced coagulation activation following infusion of a highly purified factor IX concentrate compared to a prothrombin complex concentrate

We have looked for evidence of coagulation activation in six subjects with haemophilia B by performing a single-blind active control cross-over study comparing a recently developed factor IX concentrate with a conventional prothrombin complex concentrate (PCC). Samples were obtained before infusion and at 0.25, 0.5, 1, 2, 4, 6, 12, 24, 36 and 48 h for assay of factor IX, prothrombin time, fibrinopeptide A (FPA), prothrombin fragment F1 + 2, D-dimer, thrombin-antithrombin complexes (TAT) and antithrombin III (ATIII). Following administration of the PCC there was evidence of coagulation activation in five of the six recipients for up to 6 h after the infusion. The factor IX concentrate induced a moderate degree of coagulation activation in one subject. There was no significant difference between the two products in respect of either recovery or half-life. This study provides further evidence that the new high purity preparations of factor IX concentrates produce significantly less coagulation activation than currently available PCCs. It remains to be established whether this will result in a corresponding reduction in thromboembolic complications in clinical use.

Mechanisms of platelet aggregation by Streptococcus sanguis, a causative organism in infective endocarditis

The ability of certain strains of Streptococcus sanguis to aggregate human platelets in vitro may be related to their virulence in the pathogenesis of infective endocarditis. We have studied the mechanisms of aggregation of human platelets by S. sanguis strain NCTC 7863. Platelet aggregation follows incubation of S. sanguis cells with platelet-rich plasma from normal, healthy adults, after a lag of 7-19 min. Platelet aggregation was accompanied by 5-hydroxytryptamine release and thromboxane B2 production. Aggregation was prevented by aspirin and by EDTA. Platelets from two patients with Glanzmann's thrombasthenia did not respond to bacteria. Fixed, washed platelets resuspended in normal plasma were not agglutinated by S. sanguis. Blocking the glycoprotein Ib receptor with a monoclonal antibody inhibited aggregation of PRP. However, S. sanguis did not induce von Willebrand factor (vWF) binding to platelets; nor did the bacteria prevent ristocetin-induced platelet agglutination or vWF binding. The aggregation response was not related to plasma vWF activity levels in normal subjects or in patients with von Willebrand's disease. The platelet response to S. sanguis therefore resembles true aggregation, requiring the cyclo-oxygenase pathway and the presence of glycoprotein IIb/IIIa. The mechanism also involves glycoprotein Ib, but not apparently through irreversible binding of vWF.

Hepatitis C viral RNA in clotting factor concentrates and the development of hepatitis in recipients

The polymerase chain reaction (PCR) was used to detect hepatitis C (HCV) viral sequences (HCV-RNA) in clotting factor concentrates that had been stored at 4 degrees C for 1 to 16 years. A total of 43 concentrates were tested, comprising 31 batches of factor VIII, 6 of factor IX, 2 of antithrombin III, 3 of FEIBA, and 1 of factor VII. HCV-RNA was detected in 13 of the 43 batches (30.2%). Concentrates that had not undergone viral inactivation during manufacture were significantly more likely to contain detectable HCV-RNA than concentrates that had been virally inactivated (56.3% v 14.5%, P = .006). HCV sequences were more commonly detected in concentrates made from paid donor plasma than in those made from volunteer donor plasma (44% v 11%, P = .041), and more commonly in virally inactivated concentrates with pre-1989 than with post-1989 expiration dates (50% v 0%, P = .004). Of the four batches of heat-treated products that were HCV-RNA positive, at least three transmitted non-A, non-B hepatitis (NANBH). An association between the presence of HCV-RNA in concentrates and the development of NANBH was demonstrated in nine previously untreated patients on prospective follow-up. HCV-RNA was detected in the concentrates administered to the six patients whose alanine aminotransferase (ALT) abnormalities met the diagnostic criteria for NANBH and who later seroconverted for HCV, but it was not detected in the concentrates administered to the three patients whose ALT abnormalities failed to satisfy the diagnostic criteria and who did not seroconvert. We suggest that the use of this PCR technique to monitor clotting factor concentrates derived from pooled blood may potentially contribute to product safety.

Interferon alfa for chronic hepatitis C in haemophiliacs

Chronic hepatitis C virus (HCV) associated liver disease is an important cause of morbidity and mortality in haemophilia. Recombinant interferon alfa-2b was used in a randomised controlled liver biopsy trial to treat haemophiliacs with chronic HCV. All 18 patients entered had antibodies to HCV. During the first year of the study, 10 patients were randomised on the basis of histology to receive interferon alfa-2b, 3 million units subcutaneously, thrice weekly and eight to receive no treatment (control group). After 12 months, all patients had a second liver biopsy and the control group patients were offered interferon at the same dosage but for only six months. The alanine aminotransferase (ALT) activity had returned to normal in four of 10 patients treated for one year and five of six patients treated for six months, compared with none of the eight patients in the control group (p < 0.01). Although the histological scores of the two groups were similar at entry into the study, after one year the biopsy specimens in the treated group showed significant improvement compared with controls (p < 0.01). It is concluded that interferon alfa-2b is effective in returning ALT values to normal and improving liver histology in at least 50% of patients treated.

Relationships between haemostatic factors and capillary morphology in human diabetic neuropathy

We have examined haemostatic factors in 15 diabetic patients with peripheral neuropathy and 10 diabetic patients without clinical complications. Plasma and blood viscosity, fibrinogen, factor VIIIc, von Willebrand factor activity, spontaneous platelet aggregation and fibrinolytic activity were not significantly different between diabetic patients without clinical complications and diabetic patients with peripheral neuropathy. Platelet aggregation was enhanced in diabetic patients with neuropathy compared with those without complications. In the 15 patients with neuropathy and 3 without complications, who underwent biopsy of sural nerve, skin and muscle, associations were found between haemostatic variables and measures of nerve capillary pathology, notably: plasma fibrinogen and nerve capillary basement membrane thickness (r = 0.70, p < 0.001); thromboxane B2 production and nerve capillary basement membrane thickness (r = -0.61, p < 0.01); plasma fibrinolytic activity and endoneurial capillary lumen size (r = 0.60, p < 0.01) and endothelial cell outer perimeter (r = 0.65, p < 0.01). The main associations of skin and muscle capillary abnormalities were with measures of in vitro platelet aggregation, and the correlations found with nerve capillary measurements were not echoed in the overlying muscle and skin. The results are supportive of the involvement of haemostatic abnormalities in the pathogenesis of diabetic neuropathy.