Molecular mechanisms of Ebola pathogenesis

Ebola viruses (EBOVs) and Marburg viruses (MARVs) are among the deadliest human viruses, as highlighted by the recent and widespread Ebola virus outbreak in West Africa, which was the largest and longest epidemic of Ebola virus disease (EVD) in history, resulting in significant loss of life and disruptions across multiple continents. Although the number of cases has nearly reached its nadir, a recent cluster of 5 cases in Guinea on March 17, 2016, has extended the enhanced surveillance period to June 15, 2016. New, enhanced 90-d surveillance windows replaced the 42-d surveillance window to ensure the rapid detection of new cases that may arise from a missed transmission chain, reintroduction from an animal reservoir, or more important, reemergence of the virus that has persisted in an EVD survivor. In this review, we summarize our current understanding of EBOV pathogenesis, describe vaccine and therapeutic candidates in clinical trials, and discuss mechanisms of viral persistence and long-term health sequelae for EVD survivors.

Bleeding and thrombosis in the cancer patient

There is an increased risk not only of bleeding but also of thrombosis in the cancer patient. The double jeopardy creates an additional problem in their management and requires special attention. This review provides information on pathophysiology in the regulation of hemostasis, leading to bleeding and thrombotic complications. The process is complex with multiple factors being involved. In addition to the pathogenesis, a number of clinical syndromes, diagnostic methods and the management of hemostatic abnormalities in the cancer patient are presented. Potential effects of cancer treatment on these risks magnify the hazards encountered by the managing team. Wherever management is discussed, emphasis is placed on the scientific basis for the rationale of the therapeutic approach.

von Willebrand factor mutation promotes thrombocytopathy by inhibiting integrin αIIbβ3

von Willebrand disease type 2B (vWD-type 2B) is characterized by gain-of-function mutations in von Willebrand factor (vWF) that enhance its binding to the glycoprotein Ib-IX-V complex on platelets. Patients with vWD-type 2B have a bleeding tendency that is linked to loss of vWF multimers and/or thrombocytopenia. In this study, we uncovered evidence that platelet dysfunction is a third possible mechanism for bleeding tendency. We found that platelet aggregation, secretion, and spreading were diminished due to inhibition of integrin αIIbβ3 in platelets from mice expressing a vWD-type 2B-associated vWF (vWF/p.V1316M), platelets from a patient with the same mutation, and control platelets pretreated with recombinant vWF/p.V1316M. Impaired platelet function coincided with reduced thrombus growth. Further, αIIbβ3 activation and activation of the small GTPase Rap1 were impaired by vWF/p.V1316M following exposure to platelet agonists (thrombin, ADP, or convulxin). Conversely, thrombin- or ADP-induced Ca2+ store release, which is required for αIIbβ3 activation, was normal, indicating that vWF/p.V1316M acts downstream of Ca2+ release and upstream of Rap1. We found normal Syk phosphorylation and PLCγ2 activation following collagen receptor signaling, further implying that vWF/p.V1316M acts directly on or downstream of Ca2+ release. These data indicate that the vWD-type 2B mutation p.V1316M is associated with severe thrombocytopathy, which likely contributes to the bleeding tendency in vWD-type 2B.

Impact of genetic variation on perioperative bleeding

Variation in bleeding in the perioperative period is a complex and multifactorial event associated with immediate and delayed consequences for the patient and health care resources. Little is known about the complex genetic influences on perioperative bleeding. With the discovery of multiple variations in the human genome and ever-growing databases of well-phenotyped surgical patients, better identification of patients at risk of bleeding is becoming a reality. In this review, polymorphisms in the platelet receptor genes, plasminogen activator inhibitor, and angiotensin genes among others will be discussed. We will explore the nature, effects, and implications of the genetics that influence perioperative bleeding above and beyond surgical bleeding, particularly in cardiac surgery.

An update on the platelet dysfunction in chronic myeloproliferative syndromes

The thrombotic and hemorrhagic diathesis represents a frequent complication in myeloproliferative disorders (CMPD). They are correlated with the number of platelets, but also with their qualitative disorders, such as membrane glycoprotein changes. The latter are revealed by many platelet essays including flow-cytometry and include modified activation, secretion and aggregation patterns. The thrombopoietin platelet receptor (cMPL), affected by the JAK2 V617 mutation encountered in CMPD, may be associated with a prothrombotic status. Its implication reveals the importance of the molecular genetics profile in defining molecular diagnostic hallmarks and makes it a candidate in the early diagnosis of myeloproliferative disorder and a predictor of thrombotic complications in this group of diseases.

[Coagulation disorders in cirrhosis]

The liver plays a central role in the clotting process. In this organ are sintetizated the major part of the coagulation factors. Historically, was considered that alteration in liver function causes important bleeding disorders. However, actual evidence is not in agreement with this asseveration. Decreased synthesis of clotting and inhibitor factors, decrease clearance of activated factors, quantitative and qualitative platelet defects, hyperfibrinolysis and intravascular coagulation are some of the defects observed in liver diseases. Thrombotic events, even if rare in cirrhotic patients, occur manly in the portal and mesenteric veins. The aim of the present work is to review the present evidence in coagulation disorders and liver disease.

What role do coagulation disorders play in the pathogenesis of leptospirosis?

Leptospirosis is a zoonosis of worldwide distribution, spread by the urine of infected animals. It is a major public health problem, especially in developing countries, where circumstances for transmission are most favourable. The clinical picture varies from mild disease to a severe illness with haemostatic derangements and multiorgan failure eventually leading to death. Although the haemorrhagic complications of severe disease are serious, the pathophysiology is scarcely elucidated. The complex mechanisms involved in inflammation-induced coagulation activation are extensively studied in various infectious diseases, i.e. Gram-negative sepsis. Tissue factor-mediated coagulation activation, impairment of anticoagulant and fibrinolytic pathways in close concert with the cytokine network are thought to be important. But for human leptospirosis, data are limited. Because of the growing interest in this field, the impact of leptospirosis, and the availability of new therapeutic strategies, we reviewed the evidence regarding the role of coagulation in leptospirosis and provide suggestions for future research.

Haemostatic problems in acute promyelocytic leukaemia

Despite the development of highly effective treatment strategies for acute promyelocytic leukaemia around 10% of patients die in the presentation period as a consequence of the associated bleeding diathesis. The cause of the coagulopathy is complex resulting from a combination of tissue factor (TF) and cancer procoagulant (CP) induced disseminated intravascular coagulation, exaggerated fibrinolysis due predominantly to enhanced expression of annexin II on APL blast cell membranes and blast cell production of cytokines. All-trans retinoic acid (ATRA) has revolutionised the treatment of APL. When combined with chemotherapy long term survival rates of up to 80% can be achieved. Commencement of ATRA induces APL blast cell differentiation and is associated with a rapid resolution of the bleeding tendency through a combination of effects which include up regulation of thrombomodulin and down regulation of TF and CP production and cell surface expression of annexin II.

Extractions dentaires chez l’enfant présentant une maladie hémorragique constitutionnelle : protocole thérapeutique et résultats

INTRODUCTION

We report the results of our 10-year experience with a protocol of local hemostasis specifically elaborated for children with congenital bleeding disorders.

MATERIAL AND METHOD

Sixty-four dental extractions procedures were performed in 37 children. Local hemostasis was achieved with the CO2 laser at the site of extraction previously filled with regenerated oxidized cellulose. The site of extraction was then protected with thermomolded splint. The replacement therapy (hemostasis factor concentrates, platelet concentrates) was coordinated by the hematologist and restricted as much as possible.

RESULTS

160 decidual teeth and 23 permanent teeth were extracted. None of the children with minor bleeding deficiency received replacement therapy. Ten post-operative bleedings were recorded but none was considered severe.

DISCUSSION

This protocol characterized by the use of CO2 laser for the hemostasis gave satisfaction in children. The rare and minor post-operative bleedings could be explained by multiple extractions, local infection and/or children's anxiety. This strategy requires a close cooperation between the stomatologist and the hematologist in order to determine the optimal therapeutic management.

Causes of isolated prolonged activated partial thromboplastin time in an acute care general hospital

INTRODUCTION

To determine the causes of isolated prolonged activated partial thromboplastin time (APTT) in an acute care general hospital setting so as to rationalise fresh frozen plasma usage.

METHODS

A prospective study of consecutive patients with isolated prolonged APTT presenting to our hospital between February 2002 and January 2004 was performed. All patients had normal prothrombin time and thrombin time. For all patients, an initial 50:50 correction with plasma was done and a standard panel of tests was performed. These included detection of lupus anticoagulant using two different sensitive tests; measurement of coagulant factors VIII (FVIII), IX, XI and XII, which are involved in the intrinsic arm of haemostasis; von Willebrand factor antigen (vWF:Ag) levels and for those with FVIII levels less than 10 percent, an inhibitor assay using the Nijmegen modification of the Bethesda method.

RESULTS

177 patients were included in the study. The cohort was typical of an acute care general hospital patient population in Singapore in terms of age, sex and racial distribution. The most common cause of an isolated prolonged APTT in our study was the presence of lupus anticoagulant (53.1 percent of cases). In 31.6 percent of cases, obvious cause could be detected after our panel of tests. These patients mostly had mildly prolonged APTT that could be both correctable and non-correctable by normal plasma. Prolonged APTT due to factor deficiency was relatively rare with those that may potentially cause haemorrhagic problems only accounting for 4.5 percent of cases.

CONCLUSION

Our study suggests that most of the causes of isolated prolonged APTT do not lead to haemorrhagic complications. In fact, in a majority, it may signify an underlying thrombophilic condition. As a result, prolongation of APTT should be fully investigated and correction with fresh frozen plasma should be used only when appropriate.

Main clinical manifestations of a bleeding diathesis: an often disregarded aspect of medical and surgical history taking

A suitable clinical evaluation of a bleeding diathesis is often forgone. The young doctor is often unprepared to describe in an accurate way the different types of bleeding. An adequate classification and adequate clinical information about a bleeding diathesis are instead of paramount importance. Bleeding may be cutaneous, mucous, articular, muscular, parenchymal, intracavitary, orificial. Each of these sites and forms may have diagnostic implications. An accurate description of the several forms of cutaneous bleeding (petechiae, purpuric spots, ecchymosis, haematomas, etc.) is needed for referrals and for controls. The correct evaluation of cutaneous bleeding manifestations of children (battered child syndrome) is absolutely important for clinical and medico-legal purposes. The same is true for the battering syndrome seen in women abused by their spouses. The grading of haemarthrosis in haemophilia patients is important for the follow-up. A proper description of haematuria is essential in suggesting the probable site of bleeding (kidney or bladder or urethra). A proper evaluation of bleeding may give also useful information on the general health status of the patients (presence of anaemia, poor nutrition, renal insufficiency, etc.). The combination of bleeding and thrombosis in the same patient is also a clinical challenge. The relationship between haemorrhage and thrombosis may be sequential or concomitant. Sequential thrombosis may occur in a patient confined in bed for a brain haemorrhage. Concomitant thrombosis and bleeding occur in DIC and in patients with thrombosis being treated with anticoagulants. Finally, it should be kept in mind that a proper evaluation of the bleeding diathesis of a given patient may help the caring doctor in ordering appropriate laboratory tests (e.g. a platelet count for petechiae, a PTT for a patient with haemarthrosis, etc.).

[Thrombin activatable fibrinolysis inhibitor (TAFI) and its importance in the regulation of fibrinolysis]

Thrombin activatable fibrinolysis inhibitor (TAFI) also named procarboxypeptidase U (CPU), procarboxypeptidase R (CPR) and plasma procarboxypeptidase B (CPB) provides an important link between fibrinolysis and coagulation cascade. Activated TAFI (TAFIa) reduces a generation of plasmin because it cleaves off the carboxy-terminal lysine residues from partially degraded fibrin and thereby abrogates the fibrin cofactor function in the tPA-mediated catalysis of plasminogen to plasmin. TAFI is activated by thrombin-thrombomodulin complex. TAFI transformation to the activated TAFI (TAFIa) induced by thrombin supports the important role of coagulation cascade in regulation of fibrinolysis. This can be proved by a fact that the patients with a factor XI (FXI) deficiency are prone to bleeding from tissues with a high local fibrinolytic activity (urinary tract, nose, oral cavity, tonsils) that can be explained by a decreased thrombin-mediated TAFI activation. On the other hand the prothrombotic mutation of factor V (FV Leiden) associated with a resistance to activated protein C (APC-resistance) possess both mechanisms-an increased thrombin generation in coagulation cascade and a down regulation of fibrinolysis by a way of the thrombin-induced TAFI activation. For the future an inhibition of TAFI (e.g. by FXI inhibitors) offers the therapeutic possibilities to improve the decreased fibrinolysis and increase the efficiency of fibrinolytic therapy in thrombotic disorders. In bleeding disorders (hemophilia A, B) the drugs with a higher efficiency of TAFI for down regulation of an increased fibrinolysis could be used.

Quality of life in children and families with bleeding disorders

Quality of life (QoL) in children and adolescents with bleeding disorders and their families is a relatively new topic. It is important to understand more about QoL in this patient population to evaluate and if necessary to improve the care patients receive. To achieve this aim, a questionnaire to assess patients' QoL in hemophilia was developed and psychometrically tested. Three hundred twenty hemophiliac children and adolescents from six European countries and their families were asked to fill out a questionnaire regarding different aspects of their well-being and functioning, as well as their views on hemophilia care. Generic QoL questionnaires showed that children with hemophilia have a higher QoL than other patients with chronic disease, such as asthma/atopic dermatitis and obesity. Several determinants affected patients' QoL (e.g., number of bleeds, social support). Parents' and children's assessments differed with regard to social and emotional aspects of QoL. The study showed that variations in QoL can be explained by clinical and psychosocial factors and suggested that QoL can be assessed and enhanced both by medical and non-medical (e.g., psychological) interventions.

Safety and efficacy of holmium: YAG laser lithotripsy in patients with bleeding diatheses

PURPOSE

We assessed the safety and efficacy of ureteroscopy and holmium:YAG laser lithotripsy for treating upper urinary tract calculi in patients with known and uncorrected bleeding diathesis.

MATERIALS AND METHODS

We retrospectively reviewed the charts at 2 tertiary stone centers to identify patients with known bleeding diathesis who were treated with holmium:YAG laser lithotripsy for upper urinary tract calculi. A total of 25 patients (29 upper urinary tract calculi) underwent ureteroscopic holmium laser lithotripsy. Bleeding diathesis involved warfarin administration for various conditions in 17 patients, liver dysfunction in 3, thrombocytopenia in 4 and von Willebrand's disease in 1. The mean international normalized ratio, platelet count and bleeding time were 2.3, 50 x 109/l. and greater than 16 minutes in patients on warfarin and in those with liver dysfunction, thrombocytopenia and von Willebrand's disease, respectively.

RESULTS

Overall the stone-free rate was 96% (27 of 28 cases) and 29 of 30 procedures were completed successfully without significant complication. In a patient treated concomitantly with electrohydraulic lithotripsy significant retroperitoneal hemorrhage required blood transfusion.

CONCLUSIONS

Upper tract urinary calculi in patients with uncorrected bleeding diathesis can be safely managed by contemporary small caliber ureteroscopes and the holmium laser as the only modality of lithotripsy. Ureteroscopic holmium laser lithotripsy without preoperatively correcting hemostatic parameters limits the risk of thromboembolic complications and costs associated with an extended hospital stay. Avoiding electrohydraulic lithotripsy is crucial for decreasing bleeding complications in this cohort of patients.

Prohemorrhagic potential of dipyrone, ibuprofen, ketorolac, and aspirin: mechanisms associated with blood flow and erythrocyte deformability

Dipyrone, ibuprofen, ketorolac, and aspirin were tested in a well-defined perfusion system (shear rates: 300/s, 800/s, and 1,800/s). Whole blood samples were treated with the drugs at analgesic doses and platelet interaction with damaged subendothelium was measured. All the drugs fully inhibited platelet cyclooxygenase, as assessed by classic aggregometry. Perfusion studies showed that there was a general tendency to reduce the percentage of large aggregates (thrombus; %T), to increase the percentage of adhered platelets (adhesion; %A), and to reduce the height of thrombi with respect to control. Aspirin significantly increased %A and reduced %T at all shear rates tested, whereas dipyrone had the same effect at 800/s, and ketorolac and ibuprofen at 1,800/s. In addition, aspirin significantly reduced erythrocyte deformability with respect to the other drugs. In conclusion, under our experimental conditions, aspirin showed the most remarkable effects on platelet function, closely followed by dipyrone. The effects of ketorolac were moderate, whereas ibuprofen had a minor impact on platelet function.

Orthodontic treatment of patients with medical disorders

This article will highlight some of the problems encountered when orthodontic treatment is provided for patients who have serious medical conditions. The way in which various disease processes might influence treatment decisions will be described, as well as recommended methods of avoiding potential problems.

Cytomegalovirus hemorrhagic gastritis

A 36-year-old male with acquired immune deficiency syndrome (AIDS) presented with intractable nausea and vomiting of 1 week's duration that was not attributable to his medications. An esophagogastroduodenoscopy showed hemorrhagic and necrotic gastric mucosa but no ulcers were found. Histopathology revealed viral inclusions consistent with cytomegalovirus (CMV) disease of the stomach. The patient received 6 weeks of intravenous ganciclovir with resolution of symptoms and endoscopic findings. Cytomegaloviral involvement of the stomach is rare, even in immunocompromised patients. Characteristic findings on upper endoscopy are punched-out gastric ulcers. This is a rare case of CMV disease of the stomach presenting as hemorrhagic, necrotic gastritis with inflammatory bridging.

Capillary microscopic and rheological dimensions for the diagnosis of von Willebrand disease in comparison to other haemorrhagic diatheses

It is known that angiodysplasia influence macrocirculation as well as microcirculation in patients with vWD. In the present study it was examined if intravital capillary microscopic dimensions (morphologic and dynamic) in skin (nailfold) in combination with rheologic parameters could give indications for the presence of vWD in patients with haemorrhagic diathesis. Patients with vWD (n = 100; 92 type 1: definite type 1:78 and possible type 1:14: 8 type 2A) have in comparison to patients with other haemorrhagic diathesis [thrombocytopathy (n = 122), thrombocytopenia (n = 101). severe haemophilia A (n = 50) and severe haemophilia B (n = 20). congenital dysfibrinogenaemia (n = 22), oral anticoagulation with phenprocoumone (n = 112)] and to apparently healthy subjects (n = 100) a significantly increased capillary torquation (median index: 3.5), a venolar and an arteriolar capillary dilatation (median: 16.5 microm; median: 15.1 microm) and the highest part of microscopic bleedings (extravasates) with 40% in the video capillary microscopy as morphological changes. Only the congenital dysfibrinogenaemia appears with a larger dilatation in venolar capillaries (median: 14.5 microm). Microscopic bleedings are much less common in other haemorrhagic diatheses with a frequency between 4% and 13%. In the vWD a significantly reduced duration of reactive hyperaemia (median: 150 sec). This is the only dynamic change that can be taken as a possible hint for a loss of flexibility within the precapillary vessels. A significantly reduced plasma viscosity (< 1.25 mPas) is typical for the vWD due to the increase of the shear stress in blood plasma because of the reduction of vWF-activities. Changes of the capillary morphology (dilatation, extravasates, capillary torquation) and the hypoplasmaviscosity are most sensitive for the vWD (75%, 65%, 40%, 80%) with a fairly high specifity (up to 93%) and a positive predictive value of 99%. As a conclusion it seems reasonable to discuss the introduction of video capillary microscopy as a screening test for haemostasiological and angiological centers.

Blood coagulation

Under normal circumstances, the coagulation system is balanced in favour of anticoagulation. Thrombin is the key effector enzyme of the clotting cascade. Antagonists of vitamin K inhibit a vitamin-K-dependent post-translational modification of several coagulation proteins, which is required for these proteins to attain a phospholipid-binding conformation. Heparin stimulates the activity of antithrombin, a serine-protease inhibitor. Analysis of knock-out mice has shown the relative importance of the coagulation factors in vivo. Gene therapy may soon be a therapeutic option for inherited deficiencies of factors VIII and IX.

Assessment of menstrual blood loss and gynaecological problems in patients with inherited bleeding disorders

Menstrual blood loss and gynaecological problems in patients with inherited bleeding disorders were assessed in this study. One hundred and sixteen women, including 66 with von Willebrand's disease (vWD), 30 carriers of haemophilia and 20 with factor XI (FXI) deficiency were interviewed and their gynaecological history obtained. Their case records were also reviewed and menstrual loss was objectively assessed using a pictorial blood assessment chart (PBAC). Comparison with an age-matched control group (69 women) was performed. Menorrhagia (PBAC score> 100) was confirmed in 74%, 57% and 59% of women with vWD, carriers of haemophilia and FXI deficiency, respectively, in comparison with 29% in the control group (P = 0.001). PBAC scores were higher in vWD patients with a von Willebrand factor activity (vWF:Ac) of </= 30 IU dL-1 compared to those with higher levels, but the difference was not statistically significant. However, there was no relation between PBAC score and the severity of the disease in FXI deficient patients and carriers of haemophilia. Duration of menstruation was significantly longer (P = 0.001) and episodes of flooding was significantly more common (P = 0.001) in patients with inherited bleeding disorders compared to the control group. However, there was no difference in the passage of clots during menstruation. Forty-seven per cent of patients with inherited bleeding disorders had consultations with their family practitioner or gynaecologist for menorrhagia, 36% had medical treatment and 27% had surgical procedures, including 10 hysterectomies. Post-operative bleeding followed in four out of 28 cases of hysteroscopy and/or dilatation and curettage. Bleeding complications following hysterectomy were reported in five out of 10 patients. In conclusion, menorrhagia is a common and major problem in patients with inherited bleeding disorders, especially vWD. Increased awareness among gynaecologists and haematologists of the high prevalence of menorrhagia and the treatment options available is necessary for optimal management of these patients. Appropriate preoperative assessment and haemostatic control during any gynaecological procedure, however minor, and in collaboration with the local haemophilia centre is essential to minimize risks of haemorrhagic complications.

The role of von Willebrand factor in the hemostatic defect of acute promyelocytic leukemia

Bleeding complications are often associated with acute promyelocytic leukemia (APL) they occur frequently at the onset of APL and become more serious during chemotherapy. The increased bleeding tendency of APL is caused by a massive proteolytic state, triggered by procoagulant substances, plasminogen activators and proteinases released into the circulation from leukemic cells. The introduction of all-trans-retinoic acid (ATRA) into the treatment of APL has reduced bleeding complications. However the mechanisms of the hemostatic defects in patients with APL and their modifications during ATRA with or without chemotherapy are still incompletely understood. Attempts at characterizing and monitoring these hemostatic abnormalities have been made by using several laboratory parameters. Among them we have studied the structural modifications of von Willebrand Factor (vWF). In APL, plasma vWF is massively degraded, with specific fragments produced by the action of plasmin and elastase. After ATRA therapy, proteolysis diminishes progressively in parallel with the improvement of other hemostatic measurements. We conclude that abnormalities of vWF structure and function might adversely affect hemostasis in APL and that their improvement after ATRA administration might explain in part the effectiveness of this drug in reducing hemorrhagic complications.

Dental and medical considerations of patients with renal disease

Often a dentist will have a patient with a complicated medical condition that needs to be considered when providing treatment. Following is an in-depth discussion of the medical and dental considerations of patients with renal disease.

Acquired haemophilia

Acquired haemophilia is a rare but life-threatening acquired bleeding diathesis caused by autoimmune depletion of factor VIII. This occurs most frequently in elderly patients who lack disease associations. Acquired haemophilia may also arise in association with SLE rheumatoid arthritis, Sjögren's syndrome, other autoimmune conditions, lymphoproliferative malignancy, pregnancy and as a drug reaction. Acquired haemophilia has an equal sex distribution. The aims of treatment are to eliminate the inhibitor by immunosuppression and to treat the bleeding, which is the most common cause of death in patients with acquired haemophilia. The inhibitor is abolished in up to 70% of patients using prednisolone and cyclophosphamide, although other immunosuppressive regimens may also be used. These include azathioprine, vincristine and other cytotoxic agents, high-dose immunoglobulin and cyclosporin A. Bleeding may be controlled using porcine factor VIII or recombinant factor VIIa, although human factor VIII and prothrombin complex concentrates also have a limited role as haemostatic agents in this condition.

Evaluation of bleeding disorders. A detailed history and laboratory tests provide clues

A single, optimal screening laboratory test for hemostasis would evaluate vascular, platelet, coagulation, and fibrinolytic functions. Unfortunately, such a test does not exist. The key factor in determining the presence of a bleeding diathesis is obtaining a detailed patient history. Results of coagulation tests should always be interpreted in the context of such a history. Screening tests include platelet count, PTT, and PT. Subsequent investigations depend on the results of these tests.

Severe haemorrhagic diathesis in an adult patient with cystic fibrosis after long-term antibiotic treatment of pulmonary infection

We describe the case of a 22 yr old male patient with cystic fibrosis, who, after long-term antibiotic treatment of pulmonary infection, developed a haemorrhagic diathesis with severe bleeding from the mucus membrane of the mouth, and haematuria. Rapid recovery was observed after infusion of vitamin K. During 8 months of follow-up, no evidence of recurrence of the clotting disturbances and anaemia were noted. The combination of impaired absorption of vitamin K due to underlying disease with the antibiotic-induced suppression of vitamin K synthesis by intestinal bacteria could be a possible explanation for this disorder.

Effect of all-trans retinoic acid on procoagulant and fibrinolytic activities of cultured blast cells from patients with acute promyelocytic leukemia

The mechanisms underlying acute promyelocytic leukemia (APL) coagulopathy and its reversal by administration of all-trans retinoic acid (ATRA) have been investigated. Bone marrow promyelocytic blasts from nine patients with APL were cultured with or without ATRA 1 mumol/L. Cultured blasts (days 0, 3, 6, and 9) were washed, resuspended in phosphate buffer, lysed by freezing and thawing, and then assayed for procoagulant activity (PCA), elastase activity, tissue factor (TF) antigen, tissue-type plasminogen activator (t-PA) antigen and urokinase-type plasminogen activator (u-PA) antigen. PCA was determined by a recalcification assay. Elastase was measured by an amidolytic assay (S-2484). TF, t-PA, and u-PA antigens were measured by an enzyme-linked immunosorbent assay (ELISA). Malignant promyelocytes isolated from the patients had increased levels of PCA and TF as compared with the control polymorphonucleates, and low levels of elastase, t-PA, and u-PA; the patient blast PCA level was significantly related to the degree of hypofibrinogenemia. In this system, blast PCA depended on the tissue factor and was significantly correlated to the TF antigen values. In the cultures without ATRA, PCA, TF, and u-PA progressively increased, whereas elastase and t-PA levels remained essentially unchanged. In the presence of ATRA, all parameters (except u-PA) decreased during the culture time. Thus, a major role of the promyelocytic blast cell PCA in the pathogenesis of M3-related coagulopathy is suggested; the ATRA effect on coagulopathy seems mainly mediated by a downregulation of the PCA.

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.

Hemostasis in renal disease: pathophysiology and management

The hemostatic abnormalities commonly encountered in patients with renal disease can significantly threaten the well-being of the patient and pose difficult management issues for the clinician. In this review, we explore the pathophysiology underlying the bleeding diathesis and hypercoagulability that can occur. Current therapeutic interventions are also discussed.

Flow-cytometric analysis of mepacrine-labelled platelets in patients with end-stage renal failure

Platelet dysfunction and increased bleeding tendency has been the most consistently described haemostatic abnormality in patients with renal failure. Besides abnormalities in platelet membrane glycoproteins, a reduced amount of platelet-dense granule content has been demonstrated in patients with end-stage renal failure (ESRD) indicating an acquired storage pool deficiency (SPD) present in uraemia. To study dense granules, platelets were labelled with mepacrine, a fluorescent probe which is specifically incorporated into dense bodies. MepaPlatelets of 13 patients with ESRD and of 11 healthy controls were studied. The results showed that mepacrine-labelled platelets of patients with ESRD reveal a significantly (p < 0.05) reduced fluorescence compared to the control group. This implies a reduced number or content of dense granules present in ESRD platelets. Thus, the current data indicate that ESRD is associated with an acquired platelet SPD which may be a useful and rapid method for screening patients with suspected acquired or inherited SPD.

Autoantibodies against the platelet glycoproteins (GP) IIb/IIIa, Ia/IIa, and IV and partial deficiency in GPIV in a patient with a bleeding disorder and a defective platelet collagen interaction

To evaluate the physiologic importance of the different collagen receptors on platelets, we screened 806 patients admitted to the hospital because of hemorrhagic diathesis for eventual laboratory evidence of a pathologic platelet collagen interaction, and found 5 patients with an isolated deficiency in collagen-induced platelet aggregation. Four of these five patients had a partial defect, one had a complete defect. The structural and functional analysis of the platelets from the patient with a complete defect showed a deficiency in glycoprotein (GP) IV and autoantibodies against GPIIb/IIIa, GPIa/IIa, and GPIV. Patient plasma had only a minimal effect on normal control platelets and Naka-negative platelets. The analyses of the defect in the patient and of the data in the literature suggest that a single defect may not result in clinical bleeding (GPIV-deficient patients do not bleed), but may become symptomatic in combination with another defect such as the autoantibodies against GPIa/IIa, GPIV, and/or GPIIb/IIIa, all of which are involved in platelet collagen interactions (three of four of our immune thrombocytopenic purpura patients with anti-GPIV and anti-GPIIb/IIIa autoantibodies had a bleeding disorder). We hypothesize that it is the synergism of two abnormalities that results in the defective function, a mechanism that is in agreement with earlier studies on platelet collagen interaction that suggests that a double defect in platelet collagen interactions is required to become clinically apparent.

Subclinical neuropathy in children with inherited haemostasis disorders

Motor and sensory conduction of the right peroneal and sural nerves was studied in 28 children (17 HIV seropositive) with inherited hemostasis disorders, without any symptoms of neuropathy. The amplitude ratio of the evoked muscle potential (EMP) at distal stimulation to that at proximal stimulation at the right peroneal nerve was also studied. Thirty healthy aged-matched children were used as controls. There was no statistically significant difference in the distal latency, amplitude and conduction velocity of motor and sensory nerves between patients and controls. On the contrary, a great diminution of amplitude of the EMP during proximal stimulation of nerve was observed in patients, statistically very significant, as compared to controls. This difference was independent of patients' age, severity of hemostasis defect or HIV status. In 9 patients the amplitude was within normal limits. Intraneural oozing due to trivial trauma is postulated as a possible mechanism of peroneal nerve lesion.

Prevalence of hepatitis C antibodies in patients with clotting disorders in Victoria. Relationship with other blood borne viruses and liver disease

OBJECTIVE

To elucidate the seroepidemiology of hepatitis C in patients with clotting disorders in comparison with other blood borne infections; to examine the effects of hepatitis C on liver function; and to assess the effectiveness of current screening and inactivation procedures used in preventing the transmission of blood borne viruses by clotting factor preparations.

DESIGN

A retrospective analysis of the prevalence of antibodies to hepatitis C virus (HCV), hepatitis B virus (HBV) and human immunodeficiency virus (HIV) by means of commercially available enzyme immunoassays (for antibodies to HCV and HIV) or radioimmunoassays (for HBV antibodies and surface antigen). An analysis was made of serum transaminase levels where such information was available and this was correlated with HCV status.

PATIENTS AND SETTING

Panels of sera were collected from adults and children with clotting disorders attending two Melbourne haemophilia treatment centres in 1973 (n = 33), 1980 (n = 33), 1984-1985 (n = 111) and 1987-1990 (n = 217) and tested for antibodies to HCV, HBV and HIV.

RESULTS

The prevalence of antibodies to HCV in the four panels tested was 45%, 74%, 75% and 76%, and the prevalence of markers of infection with HBV was 66%, 74%, 62% and 65% respectively. No antibodies to HIV were found in sera in Panels I and II but the prevalence in Panels III and IV was 23% and 36% respectively. In subjects in whom liver function test results were available, there was a significant association between the presence of antibodies to HCV and raised transaminase levels. Since heat inactivation of clotting factors was commenced in Australia in 1984, no new cases of transmission of HIV by clotting factors has been detected, but transmission of HCV in 19 subjects and HBV in one subject could not be excluded.

CONCLUSIONS

Hepatitis C infection in haemophiliacs has been a very frequent event, and the presence of antibodies to HCV is associated with an increased incidence of raised transaminase levels. Screening and heat inactivation of clotting factors has prevented further HIV transmission, but exposure to HBV and HCV has not been eliminated.

The development of a clinically relevant canine model of postperfusion syndrome

Investigation into the complex etiology of the postperfusion syndrome (PPS) has been limited by access to only retrospective human case studies, and performance of animal studies that examine biochemical predictors of injury rather than the PPS itself. To determine whether a reproducible canine model of the clinical syndrome was possible, seven dogs underwent cardiopulmonary bypass (CPB) with a bubble oxygenator for 0 (n = 1, sham), 2 (n = 1), 4 (n = 1), and 6 (n = 4) hours. Arterial oxygenation, chest radiographs, serum creatinine, and total leukocyte and platelet counts continued to change through the second postoperative day, illustrating the need for prolonged follow-up (48 hours) to accurately detect postperfusion organ dysfunction. The dogs that did not undergo CPB for 6 hours (n = 3) did not develop important pulmonary dysfunction postoperatively, but three of the four dogs undergoing 6 hours of CPB developed profound, persistent, arterial hypoxemia associated with radiographic, histologic, and hemodynamic evidence of severe PPS. Early evidence of renal dysfunction was also apparent within 84 hours of 6 hour CPB. It is concluded that the canine long duration (6 hour) CPB model, with prolonged (48 hour) postoperative monitoring, generates a reproducible, clinically relevant model of human PPS.

Vascular proliferation as an unusual cause of hemorrhagic diathesis in myelofibrosis

One year after splenectomy, a patient with myelofibrosis developed spontaneously large hematomas that were not due to coagulation abnormalities or functionally defective platelets. At autopsy, the liver, muscle, and skin showed extramedullary hematopoiesis associated with capillary proliferation and extravasation of blood. These findings indicate that neovascularization can be an additional cause of bleeding in myeloproliferative disorders and might be induced by neoplastic hematopoietic cells.

Haemostatic problems in acute leukaemia

Disseminated intravascular coagulation (DIC) is a frequent complication of acute leukaemia, in particular acute promyelocytic leukaemia. Although procoagulant substances released from leukaemic blast cells may induce DIC by activating conventional coagulation pathways, there is increasing evidence to suggest that direct activation of fibrinogen by proteases released from blast cells may be the predominant mechanism by which DIC is initiated. Primary fibrinolysis has also been proposed as the cause of the haemorrhagic diathesis in some cases of acute leukaemia. Although plasminogen activators have been demonstrated in leukaemic blast cells supporting this view, cases of primary fibrinolysis would appear to be rare. A bleeding tendency attributed to primary fibrinolysis may more often be the result of an exaggerated fibrinolytic response secondary to DIC. The main strategies of treatment for leukaemia associated DIC are rapid initiation of chemotherapy and vigorous blood product support until the DIC resolves once the blast cells have been eradicated. The role of heparin in the management of leukaemia associated DIC remains controversial. There is recent evidence to suggest that heparin therapy does reduce the incidence of haemorrhagic death although it has been recommended that relatively low intravenous doses should be administered initially to reduce the risk of heparin induced haemorrhage.

Measured menstrual blood loss in women with a bleeding disorder or using oral anticoagulant therapy

Bleeding disorders in women are associated with a high incidence of menorrhagia, but few objective data exist. Whether oral anticoagulant therapy in women is also associated with a higher incidence of menorrhagia is unknown. We measured menstrual blood loss in six women with various congenital or acquired bleeding disorders and in 11 women treated with oral anticoagulant therapy. Mean menstrual blood loss in women with a bleeding disorder was 219 ml (range, 60 to 568 ml); five women had menorrhagia. In women treated with oral anticoagulant therapy, mean menstrual blood loss was 98 ml (range, 9 to 239 ml), and five women had menorrhagia. Of the six women with normal menstrual blood losses, two had losses in the high normal range (60 to 80 ml). No correlation existed between anticoagulant state and menstrual blood loss. The data support the close association between bleeding disorders and menorrhagia and suggest that oral anticoagulants increase menstrual blood loss.