Replacement therapy for a homozygous protein C deficiency-state using a concentrate of human protein C and S

Unveiling the enigma: A challenging case of protein C deficiency concealed by fever and epistaxis

Protein C deficiency is a rare genetic disorder caused by mutations in the protein C, inactivator of coagulation factors Va and VIIA gene, affecting approximately 1 in 200-500 individuals. It leads to a hypercoagulable state, increasing the risk of blood clots. Symptoms vary with age, ranging from life-threatening purpura fulminans in neonates to venous thromboembolism, particularly deep vein thrombosis, in adults. A recent case involved a 21-year-old South Asian male presenting with persistent fever, weight loss, epistaxis, abdominal tenderness, and acute pain in the right thigh and leg, raising suspicion of deep vein thrombosis. Tests confirmed deep vein thrombosis in multiple leg veins and a pulmonary embolism. The patient was diagnosed with protein C deficiency and received anticoagulant therapy, thrombolysis, and an inferior vena cava filter. Complications of protein C deficiency include deep vein thrombosis, pulmonary embolism, stroke, and ischemic colitis. Diagnosis involves immunoassays and genetic analysis. Treatment includes heparin followed by anticoagulation therapy with warfarin. In severe cases, an inferior vena cava filter may be implanted. The described case required extensive treatment due to multiple deep vein thrombosis and a pulmonary embolism, with lifelong anticoagulant therapy. Early diagnosis and appropriate management are crucial in young patients with a history of venous thromboembolism to prevent and manage complications associated with protein C deficiency.

Successful ECMO treatment in patients with cerebral hemorrhage and PROC gene mutation associated with VTE: a case report

In this report, we report a case of a middle-aged male, admitted to the ICU with cerebral hemorrhage resulting from a severe high-altitude fall. The patient encountered significant challenges in oxygenation index correction, attributed to extensive embolism in both the primary and branch pulmonary arteries. Consequently, the patient underwent an immediate initiation of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) therapy, persisting for 20 days. During this treatment period, a mutation in the protein C (PROC) gene was identified. The medical team meticulously navigated the delicate balance between anticoagulation and bleeding risks. Eventually, the patient was successfully weaned off VA-ECMO and subsequently discharged. This report aims to delve into the etiology and therapeutic approaches of this uncommon case, with the intention of offering insightful reference for managing similar clinical scenarios in the future.

New plasma protein C and protein S concentrate: A synergy for therapeutic purposes

BACKGROUND AND OBJECTIVES

Deficiencies of protein C (PC) or protein S (PS) are rare diseases, characterized by mutations in the PC or PS genes, which encode plasma serine proteases with anti-coagulant activity. Severe PC or PS deficiencies manifest in early life as neonatal purpura fulminans, a life-threatening heamorrhagic condition requiring immediate treatment. First-line treatment involves replacement therapy, followed by maintenance with anti-coagulants. Replacement therapy with specific protein concentrates is currently only limited to PC, and therefore, a PC + PS concentrate represents a useful addition to therapeutic options, particularly for severe PS deficiency. Further, the production of a PC + PS concentrate from unused plasma fractionation intermediates would impact favourably on manufacturing costs, and consequently therapy prices for patients and health systems.

MATERIALS AND METHODS

Several chromatographic runs were performed on the same unused plasma fractionation intermediates using different supports to obtain a PC/PS concentrate. The best chromatographic mediums were chosen, in terms of specific activity and recovery. A full process of purification including virus inactivation/removal and lyophilization steps was set up.

RESULTS

The final freeze-dried product had a mean PC concentration of 47.75 IU/mL with 11% of PS, and a mean specific activity of 202.5 IU/mg protein, corresponding to over 12,000-fold purification from plasma.

CONCLUSION

The development of a novel concentrated PC/PS mixture obtained from a waste fraction of other commercial products could be used for its potential therapeutic role in the management of neonatal purpura fulminans pathology.

Protein C Deficiency

Protein C (PC) deficiency is a heritable or acquired risk factor for thrombophilia, with presentations varying from asymptomatic to venous thromboembolism to neonatal purpura fulminans, a life-threatening disorder. Hereditary PC deficiency is caused by mutation in the PC (PROC) gene located on chromosome 2q14.3. Heterozygous and acquired PC deficiencies are more common than homozygous deficiency. The recommended initial laboratory test measures PC activity using either clot-based or chromogenic methods. There are numerous potential interferences in PC activity testing that may result in either false-positive (falsely low activity) or false-negative (falsely normal or elevated activity) results. In the present review, we discuss common clinical presentations; laboratory testing, with a focus on potential assay interferences; treatment options; and prognosis in patients with PC deficiency.

Blood derived products in pediatrics: New laboratory tools for optimizing potency assignment and reducing side effects

Neonates and children can develop rare bleeding disorders due to congenital/acquired coagulation Factor deficiencies, or allo-immune/autoimmune complications, or can undergo surgeries at high haemorrhagic risk. They then need specialized transfusion of blood components/products, or purified blood extracted products or recombinant proteins. Blood-derived therapies conventionally used for management of affected infants with genetic/acquired deficiencies, bleeding problems (coagulation Factor reduced or missing) or thrombotic disorders (reduced or missing anticoagulant proteins) pose some additional risks. These remedial therapies can cause tolerance when used very early in life and, sometimes needed, repeatedly. The introduction of recombinant proteins has allowed manufacturers to produce large amounts of the proteins usually present at very low concentration in blood. This has also changed the risk pattern of plasma-extracted products, especially in terms of continual reduction of viral transmission. Many efforts have been made over these past decades to reduce the risks associated with the use of all these products in terms of viral and bacterial safety, as well as immune disorders but they are not the objective of this article. Other associated side effects are the presence of undesired activities in blood products, which can produce thrombotic events or adverse reactions. The progressive introduction of blood derived products has greatly improved the prognosis and quality of life of affected patients. This concerns whole blood, but also blood cell concentrates, mainly platelets and red blood cells, plasma, while the blood extracted products are increasingly replaced by recombinant proteins. All these therapeutic products, i.e. blood extracted drugs, improve health and quality of life for hemophiliac's A or B, or patients with auto/allo-immune thrombocytopenias or with rare bleeding disorders, and those with thrombotic events occurring in childhood, which are mainly due to Protein C or Protein S deficiencies (congenital or acquired). Progress in analytical methods and biotechnology allow better control of the manufacturing processes for all blood derived or plasma extracted products and recombinant proteins, and contribute to improved manufacturing processes to minimize the occurrence of side effects. These adverse events can be due to the aging of the blood cell concentrate with release of their granule content, and generation of EVs, which can produce anaphylactic reactions and risk of thrombosis, but also to the presence of activated coagulation Factors in purified products, such as Factor Xia as recently identified in immunoglobulin concentrates. Characterization and measurement of contaminant products is of special usefulness during product preparation and for optimization of manufacturing processes for purified extracted products, but also for recombinant proteins. The pharmaceutical industry introduces these new methods for validating manufacturing processes, or for quality control assessments. The objective is first to warrant the full quality and safety of the lots produced, and assure the highest efficacy with the lowest risks when used in patients. For cell concentrates and fresh blood, storage conditions are critical and measurement of analytes such as EVs or Annexin V allows evaluation of quality of each individual transfused pouch. In addition to all the rules around viral and bacterial transmission risk, and immune tolerance, our available laboratory methods contribute to reducing the side effects of blood cell concentrates and derived plasma products, as well as those of the therapeutic recombinant proteins.

Effects of erdosteine on hemostasis

Aim: In this study, the effects of erdosteine (ED) on the platelet function and coagulation were investigated in adult rats. Materials and Method: Twenty-eight male Wistar albino rats were divided into four groups. The control rats in group I ( n = 7) were given only 0.5 cc of normal saline daily through oral gavage. Group II ( n = 7) rats were administered 3 mg/kg ED through oral gavage for 3 days; while group III ( n = 7) rats were given 10 mg/kg ED through oral gavage for 3 days; and group IV ( n = 7) rats were administered 30 mg/kg ED through oral gavage for 3 days. Prothrombin time (PT), activated prothromboplastin time (aPTT), international normalized ratio (INR), coagulation factors and complete blood counts were measured from the blood drawn. Results: There were a lot of differences between ED groups and control group, and among ED groups. The found differences were level of PT, aPTT, INR, coagulation factors, and number of platelets. Discussion: We consider that ED which is used as a mucolytic agent in child clinics may affect hemostasis and coagulation in a dose-dependent manner. ED should be used carefully by the patients with coagulation disorders, since there is no information available in the package insert and literature screening regarding the effect of ED.

Severe congenital protein C deficiency: the use of protein C concentrates (human) as replacement therapy for life-threatening blood-clotting complications

The protein C pathway has an important function in regulating and modulating blood coagulation and ensuring patency of the microcirculation. Protein C deficiency leads to macro- and microvascular thrombosis. Congenital severe protein C deficiency is a life-threatening state with neonatal purpura fulminans and pronounced coagulopathy. Patients with heterozygous protein C deficiency have an increased risk for thromboembolic events or experience coumarin-induced skin necrosis during initiation of coumarin therapy. Replacement with protein C concentrates is an established therapy of congenital protein C deficiency, resulting in rapid resolving of coagulopathy and thrombosis without reasonable side effects. This article summarizes the current knowledge on protein C replacement therapy in congenital protein C deficiency.

Dual effects of erdosteine on hemostasis via its different metabolites in young rats

Aim: In the study, we examined erdosteine’s effects on platelet functions and coagulation. Materials and methods: A total 29 young albino Wistar rats were divided into four groups. Control rats ( n = 6) were given saline; Group 1 rats ( n = 7) were given 3 mg/kg erdosteine by oral gavage for 3 days; Group 2 rats ( n = 7) were given 10 mg/kg erdosteine by oral gavage for 3 days; and Group 3 rats ( n = 9) were given 30 mg/kg erdosteine for 3 days. Twenty-four hours after the final dose, blood samples were drawn from a portal vein. Prothrombin time (PT), activated partial thromboplastin time (aPTT) and international normalized ratio (INR) were measured, and platelet counts were examined in a peripheral blood smear by light microscopy. Results: PT and INR values of Group 1 increased compared to the controls but did not change in Group 3. Hemostatic parameters were not measured in Group 2 because the blood samples in Group 2’s tubes clotted rapidly. Platelet counts of the peripheral blood from Group 2 were low but were normal in other groups. Conclusion: We have concluded erdosteine may disrupt hemostasis parameters by its different metabolites in patients. Erdosteine has dual effects on hemostasis via its different metabolites, which occur in different doses.

Use of human protein C concentrates in the treatment of patients with severe congenital protein C deficiency

Protein C is one of the major inhibitors of the coagulation system that downregulate thrombin generation. Severe congenital protein C deficiency leads to a hypercoagulability state that usually presents at birth with purpura fulminans and/or severe venous and arterial thrombosis. Recurrent thrombotic events are commonly seen. From the 1990’s, several virus-inactivated human protein C concentrates have been developed. These concentrates currently constitute the therapy of choice for the treatment and prevention of clinical manifestations of severe congenital protein C deficiency. This review summarizes the available information on the use of human protein C concentrates in patients with severe congenital protein C deficiency.

Venous thromboembolism in children

With improved pediatric survival from serious underlying illnesses, greater use of invasive vascular procedures and devices, and a growing awareness that vascular events occur among the young, venous thromboembolism (VTE) increasingly is recognized as a critical pediatric concern. This review provides background on etiology and epidemiology in this disorder, followed by an in-depth discussion of approaches to the clinical characterization, diagnostic evaluation, and management of pediatric VTE. Prognostic indicators and long-term outcomes are considered, with emphasis on available evidence underlying current knowledge and key questions for further investigation.

Severe congenital protein C deficiency: description of a new mutation and prophylactic protein C therapy and in vivo pharmacokinetics

Severe congenital protein C deficiency is a rare life-threatening disorder that presents with purpura fulminans, disseminated intravascular coagulation, and thrombotic complications during the neonatal period. Affected children require acute replacement therapy with fresh frozen plasma or protein C concentrate, for example, Ceprotin (Baxter AG, Vienna). Long-term management and outcome is dependent on effective anticoagulation with warfarin, low-molecular weight heparin, or protein C concentrate. We describe the successful use of intravenous protein C concentrate for thrombotic prophylaxis in 2 sisters with severe type I protein C deficiency. Individualized long-term prophylactic regimens were developed based on clinical response. In vivo pharmacokinetic analyses of protein C concentrate were performed in each patient. Analysis of the protein C gene coding sequences identified 2 mutations in both patients, the previously described Arg169 to Trp mutation, and a novel mutation that changes Cys17 into a stop codon.

Antithrombotic Therapy in Children*

This article about antithrombotic therapy in children is part of the 7th American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh the risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this article are the following. In neonates with venous thromboembolism (VTE), we suggest treatment with either unfractionated heparin or low-molecular-weight heparin (LMWH), or radiographic monitoring and anticoagulation therapy if extension occurs (Grade 2C). We suggest that clinicians not use thrombolytic therapy for treating VTE in neonates, unless there is major vessel occlusion that is causing the critical compromise of organs or limbs (Grade 2C). For children (ie, > 2 months of age) with an initial VTE, we recommend treatment with i.v. heparin or LMWH (Grade 1C+). We suggest continuing anticoagulant therapy for idiopathic thromboembolic events (TEs) for at least 6 months using vitamin K antagonists (target international normalized ratio [INR], 2.5; INR range, 2.0 to 3.0) or alternatively LMWH (Grade 2C). We suggest that clinicians not use thrombolytic therapy routinely for VTE in children (Grade 2C). For neonates and children requiring cardiac catheterization (CC) via an artery, we recommend i.v. heparin prophylaxis (Grade 1A). We suggest the use of heparin doses of 100 to 150 U/kg as a bolus and that further doses may be required in prolonged procedures (both Grade 2 B). For prophylaxis for CC, we recommend against aspirin therapy (Grade 1B). For neonates and children with peripheral arterial catheters in situ, we recommend the administration of low-dose heparin through a catheter, preferably by continuous infusion to prolong the catheter patency (Grade 1A). For children with a peripheral arterial catheter-related TE, we suggest the immediate removal of the catheter (Grade 2C). For prevention of aortic thrombosis secondary to the use of umbilical artery catheters in neonates, we suggest low-dose heparin infusion (1 to 5 U/h) (Grade 2A). In children with Kawasaki disease, we recommend therapy with aspirin in high doses initially (80 to 100 mg/kg/d during the acute phase, for up to 14 days) and then in lower doses (3 to 5 mg/kg/d for > or = 7 weeks) [Grade 1C+], as well as therapy with i.v. gammaglobulin within 10 days of the onset of symptoms (Grade 1A).

Chromatographic purification and properties of a therapeutic human protein C concentrate

Protein C deficiency (inherited and acquired) has a relatively high incidence rate in the general population worldwide. For many years, protein C deficient patients have been treated with fresh frozen plasma, prothrombin complex concentrates, heparin or oral anticoagulants, which all have clinical drawbacks. We report the production process of a highly purified human protein C concentrate from 1500 l of cryo-poor plasma by a four-step chromatographic procedure. After DEAE-Sephadex adsorption, protein C was separated from clotting factors II, VII and IX by DEAE-Sepharose FF and further purified, using a new strategy, by an on-line chromatographic system combining DMAE-Fractogel and heparin-Sepharose CL-6B. In addition, the product was treated against viral risks by solvent-detergent and nanofiltration on 15-nm membranes. The protein C concentrate was essentially free of other vitamin K-dependent proteins. Proteolytic activity was undetectable. Neither activated protein C, prekallikrein activator, nor activated vitamin K-dependent clotting factors were found resulting in good stability of the protein C activity. In vitro and in vivo animal tests did not reveal any sign of potential thrombogenicity. The final freeze-dried product had a mean protein C concentration of 58 IU/ml and a mean specific activity of 215 IU/mg protein, corresponding to over 12000-fold purification from plasma. Therefore, this concentrate appears to be of potential benefit for the treatment of protein C deficiency.

Chelator, metal ion and buffer studies for protein C separation

Protein C (PC) is the pivotal anticoagulant and antithrombotic in the human coagulation cascade. PC deficiency can result in major medical problems such as deep vein thrombosis (DVT), leading to tissue oxygen deprivation. PC treatment has no bleeding or skin necrosis problems because it circulates in the blood as a zymogen and is only activated when and where it is needed. One source of PC is transgenic animal milk. The major components in the milk, such as alpha-casein, beta-casein, kappa-casein, alpha-lactalbumin and beta-lactoglobulin, are proteins that must be separated from PC. Immobilized metal affinity chromatography (IMAC) is an inexpensive separation technology with relatively high specificity, and it has great potential for difficult protein separations. After systematic studies of different chelator, metal ion and buffers, the combination of iminodiacetic acid (IDA) and Fe was found to be effective to separate PC from major milk components. alpha-Lactalbumin and beta-lactoglobulin fell through the column in the starting buffer. PC was eluted. alpha-Casein, beta-casein, kappa-casein remained bound in the column after PC elution. This technology might be applied for PC separation from transgenic animal milk. It is very important for PC production in large quantities and at low cost to treat PC-deficient patients.

Neonatal purpura fulminans due to homozygous protein C deficiency

Severe and recurrent purpura fulminans developed in a Turkish boy at 1 week of age. Initial coagulation studies performed were compatible with disseminated intravascular coagulation. Subsequent investigations showed that the patient had homozygous and his healthy parents had heterozygous protein C deficiency. The episodes of purpura fulminans were controlled by infusions of fresh frozen plasma and heparinization. Oral anticoagulant therapy was given in the symptom-free period.

Large-scale production and properties of immunoaffinity-purified human activated protein C concentrate

Activated protein C (APC) is a highly specific serine proteinase which functions as an important naturally occurring antithrombotic enzyme. APC also has anti-inflammatory properties. We have developed a large-scale process for the production of APC for therapeutic use starting with cryoprecipitate-poor human plasma. This report describes the process, its performance at the pilot plant scale, and the characteristics of immunoaffinity-purified human APC concentrate referred to as APC (human). The process consists of three chromatographic steps, an enzymatic conversion step, and incorporates a solvent/detergent treatment step for the inactivation of lipid-enveloped viruses. Solvent/detergent was shown to rapidly inactivate spiked HIV-1, as well as three marker viruses to nondetectable levels under process conditions. The immunoaffinity-purified protein C (PC) intermediate was enriched 13,600-fold over plasma and had a specific activity of 231 U/mg. The overall yield of the process following enzymatic conversion of the PC intermediate to APC and its processing by anion exchange chromatography was 36%. APC (human) was shown to be highly purified, functional and stable.

Varicella and thrombotic complications associated with transient protein C and protein S deficiencies in children

We report six cases of protein S deficiency secondary to varicella. Five cases were complicated by thrombotic and vascular events, namely purpura fulminans and necrotic vasculitis, deep vein thrombosis and stroke. Two cases were associated with protein C deficiency and one case revealed a heterozygous factor XII deficiency. The underlying mechanism of this acquired protein S deficiency is unclear but could be related to a direct effect of zoster virus.

Protein C survival during replacement therapy in homozygous protein C deficiency

Homozygous protein C (PC) deficiency is a rare genetic defect that usually results in fatal thrombotic complications (purpura fulminans and DIC), but it can be successfully managed with oral anticoagulants or PC replacement. The successful use of PC replacement for two individuals is described. The activity and antigen levels of PC in fresh frozen plasma (FFP) and prothrombin complex concentrate (PCC) are also reported. The concentration of PC in FFP is 87 +/- 15 units/dl. PC is present in all PCC analyzed; however, a ten-fold difference between the various brands and/or lots is noted. The PC activity and antigen correlates well with no significant levels of APC. Upon infusion of FFP into two homozygous PC-deficient children, the PC levels obtained were less than or equal to 30 units/dl post-infusion and undetectable after 12-18 hr. With infusions of PCC, plasma levels of PC obtained were 100-145 units/dl and less than 10 units/dl after 48 hr. The percent recovery and half-lives of PC from FFP and PCC were 49.8% and 7.8 hr, and 84% and 7.4 hr, respectively. One infant was treated every 48 hr for 2 years without significant purpura fulminans or DIC complications. The levels of the other PC system components did not change during the infusion of the PC-rich material. Based on this information, a specific replacement protocol has been developed using a PC-rich concentrate. However, several problems may arise with the "less pure" PC-rich concentrates: catheter-tip thrombosis, related large vessel thrombosis and blood-transmitted diseases. With a specific PC concentrate, replacement therapy is a viable alternative for the long-term management/treatment of homozygous PC deficiency.

Protein C and S deficiency in severe infectious purpura of children: a collaborative study of 40 cases

We studied, in 40 children (mean age: 52 months) with severe infectious purpura, the relationships between protein C (PC) and protein S (PS) levels, and shock, disseminated intravascular coagulation (DIC) and outcome. We determined, on admission, PC antigen (ELISA) and activity (chromogenic test), and total PS (ELISA). Results were expressed as % of normal adult values. Statistical analysis was performed with SAS. Thirty children were in shock, 20 had DIC. All children with DIC, and 10 without DIC were in shock. Of 20 children who were in shock and had DIC, 7 died and 3 had an amputation. PC antigen was significantly decreased in shock children (p less than 0.05), in children with DIC (p less than 0.0005), and in non-survivors (p less than 0.05). PC activity was significantly decreased in shock children (p less than 0.05), in children with DIC (p less than 0.0005), and in non-survivors (p less than 0.005). Total PS was not decreased in shock children, but was significantly decreased in children with DIC (p less than 0.005), and in non-survivors (p less than 0.005). We conclude that PC and PS levels were decreased in our children, and that PC levels were significantly decreased in the presence of shock, DIC, and fatal outcome. PC and antithrombin III (AT III) supplementation, should be evaluated in children with severe infectious purpura with shock and DIC.

[The clinical importance of protein C and S deficiency for surgical patients]

Protein C and S are important factors in blood coagulation reported in many papers about people who suffered from thromboembolic diseases related to inherited or acquired deficiencies. Homozygous protein C/S deficiency is lethal in most cases without therapy. Heterozygous deficiency is moderate and complications occur between the 20.-50. year of age. Acquired protein C/S deficiency is a strong parameter for liver function. The typical clinical manifestations of protein C/S deficiencies are superficial and deep leg vein thrombosis, thrombosis of the mesenterial, cerebral, renal and axillary veins, portal vein thrombosis and pulmonary embolism. Most of the affected people live disease free over a longer period and develop thromboembolic complications during and after trauma, surgical interventions, pregnancy and puerperium. We report our experience with a 60 years old male who had developed a severe bilateral iliofemoral vein thrombosis with signs of pulmonary embolism after total hip replacement. An extended functional protein C deficiency (type II) was investigated by coagulation tests (Protein C Reagent, coagulometric from Behring Institute). A second female patient developed a descending iliofemoral vein thrombosis during pregnancy. Venous thrombectomy with arteriovenous fistula was performed, but reocclusion occurred after delivery. Redo-surgery was undertaken and a second reocclusion took place 10 days later. Further lysis therapy was not able to reopen the venous system. Whereas immunological and functional protein C levels showed normal ranges, the functional protein S level was markedly reduced (IL-Instrumentation Laboratory Protein S-Test).

Monoclonal antibodies against human plasma protein C and their uses for immunoaffinity chromatography

Human protein C, isolated by conventional multistep methods, was used for immunization of mice. Monoclonal antibodies were prepared and screening of antibodies to human protein C was achieved using an immunoblotting technique. Five monoclonal anti-protein C antibodies were compared as affinity ligands. Different parameters were studied (adsorption capacity, specificity of adsorption, possibility of desorption under mild conditions) and two antibodies were selected. One antibody allows preparation of highly purified protein C in a single-step procedure from a fraction of plasma containing high levels of coagulation factors whereas the other can be used for preparation of protein C deficient plasma.

Homozygous protein C deficiency in two siblings

Homozygous protein C (PC) deficiency is reported in two siblings (girl and boy) who received their proper diagnoses at the ages of 7 4/12 and 1 3/12 years respectively. The girl had perinatal asphyxia without bleeding. At 1 year of age she developed purpura fulminans. Treatment with heparin and plasma was successful. At 7 4/12 years she developed tender, bluish nonnecrotic skin changes after an orthopedic operation. The PC level was 0.08 U/ml. The boy had had a large intraventricular hemorrhage neonatally and developed severe brain damage. At 1 3/12 years he manifested the same skin changes as his sister and was treated similarly. The PC level was 0.05 U/ml. Both children now receive warfarin continuously and are essentially free of symptoms. The cases represent homozygous phenotypes in a family with a recessive trait of PC deficiency without thrombotic disease. The cases also show that severe PC deficiency may be compatible with life beyond infancy without any specific therapy.

Clinical evaluation of protein C: a comparative review of antigenic and functional assays

Thromboembolic disease is a major complication of protein C (PC) deficiency, which is among the increasing number of recognized causes of hereditary thrombotic disease. The laboratory evaluation of PC is of the utmost importance in the accurate diagnosis of this deficiency. In this review, we describe the various types of clinical antigenic and activity assays of PC. The attributes of each type of assay are discussed, as well as the value of each assay in diagnosing the various acquired and hereditary deficiencies of PC. This basic review is intended for laboratories planning to institute PC assays.

The effect of near-normoglycaemic control on plasma levels of coagulation factor VII and the anticoagulant proteins C and S in insulin-dependent diabetic patients

The present prospective follow-up study was made to study the effect of glycaemic regulation on levels of factor VII, protein C and protein S in 15 insulin-dependent diabetic patients without manifestations of vascular disease. Patients were tested before and after 8 weeks of 'metabolic' intervention, whereby a near-normoglycaemic state was achieved. At baseline, values of cross-linked fibrin degradation products (XL-FDP) and levels of 'total' protein S were significantly increased and protein C values were decreased in the diabetic patients when compared to control subjects, whereas levels of factor VII and 'free' protein S were near normal. After 'metabolic' intervention a decrease of all haemostatic parameters were recorded, however XL-FDP levels did not decline to control levels and the imbalance of factor VII and protein C persisted. When patients with newly diagnosed diabetes (n = 8) were compared to those with long-term disease (n = 7) higher levels of factor VII, protein C and protein S were recorded in the latter group before and after metabolic intervention; at baseline the differences reached statistical significance for factor VII and protein S, and remained significant for factor VII after metabolic intervention. Before and after intervention XL-FDP levels were higher in patients with newly diagnosed disease than in patients with long-term diabetes. The correlation analysis revealed positive correlations of factor VII, protein C and protein S to cholesterol and triglycerides, of protein S to all glycaemic control parameters, negative correlations of protein C to glucose, and of XL-FDP to factor VII, protein C and protein S. The results indicate an imbalance of haemostasis towards thrombophilicity in insulin-dependent diabetic patients, not completely correctable by glycaemic control.