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At least 1,243 records · Page 69Linked to original sources
PubMed1996

The reduction of large von Willebrand factor multimers in plasma in essential thrombocythaemia is related to the platelet count.

We have investigated the relationship between platelet count and large VWF (von Willebrand factor) multimers in the plasma of 36 patients with essential thrombocythaemia (ET) and 26 patients with reactive thrombocytosis (RT). In both ET and RT patients an inverse relationship could be established between platelet count and large VWF multimers in plasma as well in relatively decreased ristocetin cofactor/von Willebrand factor antigen and collagen binding activity/von Willebrand factor antigen ratios. A normalization of the platelet count was accompanied by restoration of a normal plasma VWF multimeric distribution. Our data suggest that increasing numbers of platelets circulating in blood result in increased removal of large VWF multimers from plasma.

Adult↗
PubMed1997

Clinical features at diagnosis in 430 patients with chronic myeloid leukaemia seen at a referral centre over a 16-year period.

To determine major presenting features of chronic myeloid leukaemia (CML) in current practice, we have reviewed the records of 430 patients with CML referred to the Hammersmith Hospital for allogeneic bone marrow transplantation since 1981. Approximately 20% of cases were diagnosed incidentally. Symptoms such as fatigue and weight loss were associated with greater degrees of leucocytosis and splenomegaly and lower haemoglobin levels. Most bleeding patients had normal or elevated platelet counts, suggesting that platelet dysfunction was the primary cause of haemorrhage. Although thrombocytosis was common, thrombosis was not seen. Male patients and the relatively young presented with higher WBC counts and larger spleens. The reason that these groups were diagnosed with more advanced leukaemia is not clear. Although retrospective and limited to a select group of relatively young patients, this is the largest series to be reported on CML at diagnosis, and the first such report in modern clinical practice.

Adolescent↗
PubMed1999

Hereditary thrombocythaemia in a Japanese family is caused by a novel point mutation in the thrombopoietin gene.

Hereditary thrombocythaemia (HT) with clinical features very similar to essential thrombocythaemia (ET) has been found to be transmitted as an autosomal dominant trait in several families. Here we studied the pathogenesis of HT in a previously described Japanese kindred. We found markedly elevated thrombopoietin (TPO) serum levels in all affected individuals and identified a novel point mutation in the TPO gene, a G --> T transversion at position 516 of the TPO mRNA (G516T) that co-segregated with the HT phenotype in all affected family members. This mutation is located in the 5'-untranslated region (5'-UTR) of the TPO mRNA and when assayed in reticulocyte lysates, improved translational efficiency of in vitro transcribed TPO mRNA. Cell lines transfected with the mutant TPO cDNA secreted up to 8-fold more TPO protein than cells transfected with the normal cDNA. We provide a molecular model of how the mutation partially disables the physiologic repression of TPO translation and thereby causes thrombocytosis. This is the third family in which HT has been caused by the loss of translational inhibition of TPO mRNA.

Female↗
PubMed1999

Acute myocardial infarction following toxic epidermal necrolysis?

We describe a 29-year-old woman with rheumatoid arthritis who suffered an acute myocardial infarction 70 days after an initial presentation with toxic epidermal necrolysis (TEN). The trigger for the TEN was probably an over-the-counter anti-influenza treatment containing tipepidine hibenzate. Although the patient had familial hypercholesterolemia, we believe that thrombocytosis, induced by the inflammatory response and metabolic stress resulting from the TEN, may also have played a significant role in the pathogenesis of the myocardial infarction. Although TEN manifests itself principally as a skin disease, the potential for systemic morbidity, including cardiovascular abnormalities, should also be remembered.

Adult↗
PubMed2001

Aggressive, extensive, vasculitic leg ulceration associated with hydroxyurea therapy and a fatal outcome.

The association of lower leg ulcer development and hydroxyurea therapy in patients with myeloproliferative disorders has been reported previously. In most of these cases the ulcers healed with cessation of the hydroxyurea together with meticulous attention to wound care. We report a patient who developed painful vasculitic ulcers secondary to hydroxyurea on both lower legs whilst on long-term hydroxyurea therapy for idiopathic thrombocytosis. The ulcers extended relentlessly despite stopping hydroxyurea, maximizing topical therapies and starting intensive systemic treatment. We discuss the association of hydroxyurea therapy with the development of painful ulceration.

Aged↗
PubMed1999

Circulating thrombopoietin in reactive conditions behaves like an acute phase reactant.

In a recent study we found elevated thrombopoietin (TPO) levels along with a trend toward correlation between serum TPO and some acute phase reactants (APR) in patients with reactive thrombocytosis. In order to further clarify the behaviour of TPO in reactive conditions and to highlight the eventual drawbacks of serum TPO (sTPO) against plasma TPO (pTPO) measurements, serial measurements were made of sTPO, pTPO, interleukin (IL)-6, C-reactive protein (CRP), fibrinogen (FBG), and erythrocyte sedimentation rate (ESR) in 12 patients before and at the 3rd, 7th, 14th, 45th day after hip replacement surgery. Platelet count, sTPO and pTPO were also measured in 30 healthy donors. As expected sTPO were significantly higher than pTPO levels (approximately 30% on average) both in controls (P < 0.00001) and in patients (P < 0.00001). Overall a very good correlation (r = 0.975, P < 0.00001) was found between serum and plasma TPO, whereas no correlation was found between platelet count and the sTPO/pTPO ratio indicating that the difference between sTPO and pTPO is independent from platelet count. So both serum and plasma seem to be suitable samples for TPO measurement if it is taken into account that sTPO are about 30% higher than pTPO. All the parameters we measured in our patients increased during the post-surgery period and returned to the basal value at the 45th day. pTPO levels peaked at the 3rd day, preceding by 11 days the peak in platelet count. A significant correlation was found between pTPO and ESR (P = 0.012), pTPO and FBG (P = 0.044), pTPO and CRP (P = 0.033), and a nearly significant correlation between pTPO and IL-6 (P = 0. 054). These results indicate that, in the course of reactive conditions, an early rise in TPO precedes and probably induces a later increase in platelet count. Moreover, the significant correlations along with the similarity in the chronological variations between TPO and some APRs suggest that TPO behave like an APR.

Acute-Phase Proteins↗
PubMed1996

POEMS syndrome, arterial thrombosis and thrombocythaemia.

The case of a 22-year-old man with polyneuropathy, endocrinopathy, skin change and monoclonal gammopathy of IgG-lambda type is described. There was no solitary plasmocytoma, osteosclerotic myeloma or Castleman's disease. However, significant thrombocytosis occurred and the patient developed arterial thrombosis, these were attributed to essential thrombocythaemia in the absence of other aetiological factors.

Adult↗
PubMedDate not supplied

Therapeutic plateletpheresis in thombocythemia.

Patients with myeloproliferative thrombocythemia have usually been managed with chemotherapy. Generally, removal of platelets from such patients has been performed intermittently to lower the platelet mass rapidly when neurologic or hemorrhagic complications were manifest or concurrently with the initiation of chemotherapy. A platelet count of 1,000,000/microliter or less was maintained by the use of repeated plateletpheresis over a period of three months in a patient with essential thrombocythemia, who had frequent syncopal episodes. A second patient with secondary thrombocytosis, who sustained two cerebrovascular accidents, underwent intermittent plateletpheresis over a 22-day period until her underlying disorder improved. It is concluded from the experience, combined with that of others, that plateletpheresis is not only a life-saving procedure in an acute episode but may also be used to maintain a lowered platelet count over a prolonged period in selected patients with primary thrombocythemia, in whom chemotherapy cannot be undertaken, and in symptomatic patients with secondary thrombocythemia.

Adult↗
PubMedDate not supplied

Improvement of platelet function following plateletpheresis in patients with myeloproliferative diseases.

Four patients with myeloproliferative diseases and acute hemorrhagic or thrombotic complications of thrombocytosis were treated with plateletpheresis by discontinuous-flow centrifugation. Reduction of platelet counts was achieved rapidly, without complications and was associated with clinical improvement. In all four cases, abnormal platelet aggregation testing was present before pheresis, but improved immediately after pheresis. Platelet-sizing data obtained in one case suggested that during the pheresis procedure, a population of larger volume platelets was selectively removed. The efficacy of plateletpheresis in these clinical situations may be related to the selective removal of a large abnormal platelet population.

Acute Disease↗
PubMed2003

Diagnosis of the myeloproliferative disorders: resolving phenotypic mimicry.

With the exception of chronic myelogenous leukemia (CML), which is characterized by the constitutively active chimeric bcr-abl tyrosine kinase, the diagnosis of the myeloproliferative disorders (MPD), polycythemia vera (PV), essential thrombocytosis (ET), and idiopathic myelofibrosis (IMF), is unaided by specific biologic markers and is complicated by phenotypic mimicry. Diagnosis is largely clinical with assistance from conventional laboratory techniques. Although the sine qua non of PV is erythrocytosis, survey data indicate that approximately 22% of American Society of Hematology members diagnose PV without the benefit of red blood cell mass and plasma volume measurements. These tests are essential in any suspected case of PV because erythrocytosis can be masked by an elevated plasma volume in this disorder. Recognition of defective platelet thrombopoietin receptor (Mpl) expression and overexpression of the PRV-1 gene in PV neutrophils has led to studies demonstrating the potential use of these molecular abnormalities as diagnostic markers for PV and for risk-stratifying patients with ET for disease conversion to PV or IMF. Enumeration of peripheral blood CD34(+) cells may prove useful in the diagnosis of IMF if current data regarding the disease-related specificity of this measurement are validated prospectively in larger numbers of patients.

Biomarkers↗
PubMedDate not supplied

[Kawasaki syndrome in infants in the first 6 months of life].

Diagnosis in Kawasaki disease usually is made on the so called main symptoms and on laboratory findings. The analysis of three cases in the first six months of life demonstrated that the typical symptoms concerning the mucosa and the lymphatic nodes are rare in this age group, whereas drug resistant fever and polymorphic exanthema was present in all patients. Besides that accessory symptoms like abacterial meningitis and pathologic urine analysis seemed to be frequent signs. Laboratory findings such as pathologic blood sedimentation rate, elevated CRP and thrombocytosis on the other hand were helpful in making the diagnosis.

Aneurysm↗
PubMed1994

Aplasia cutis congenita, elevated alpha-fetoprotein, and a distinct amniotic fluid acetylcholinesterase electrophoretic band.

Aplasia cutis congenita affecting the elbows, knees, hips, and gluteal area was observed in a female newborn, product of a twin pregnancy. One of the twins was a fetus papyraceous detected at 15 weeks of pregnancy. During the course of the pregnancy, maternal thrombocytosis was diagnosed and treated with aspirin. alpha-Fetoprotein was elevated in maternal serum and amniotic fluid, and a distinct electrophoretic acetylcholinesterase band was seen in amniotic fluid. These findings are in agreement with the classification of aplasia cutis congenita as proposed by Frieden et al in which type V is related to the presence of a fetus papyraceous or placental infarcts. The findings in the present case may be explained by the effect of the dead twin on the surviving fetus and the extensive denuded skin areas. Long-term follow-up of the infant showed that the lesions were cured, most of them with minimal scars. Increased risk for aplasia cutis congenita should be considered when elevated maternal and amniotic fluid alpha-fetoprotein and a distinct electrophoretic band of acetylcholinesterase are found. Especially when one of the twins is dead.

Acetylcholinesterase↗
PubMed1997

Acquired von Willebrand disease in patients with high platelet counts.

For patients with high platelet counts an inverse relationship has been established between platelet counts and large vWf multimers in plasma. Platelets are currently thought to be primarily involved in the pathogenesis of this decrease in plasma large vWf multimers, presumably by binding large vWf multimers, resulting in their effective removal from the circulation and/or by degrading (platelet-bound) vWf. In patients with myeloproliferative disorders associated with high platelet counts, a decrease in large vWf multimers in plasma may potentially compromise primary hemostasis. Patients with reactive thrombocytosis exhibit a similar reduction in large vWf multimers in plasma, but their clinical course is usually not complicated by bleeding, probably as a consequence of increased circulating vWf levels due to the behavior of vWf as a reactive protein, which compensates for the relatively decreased levels of large vWf multimers in plasma.

Adult↗
PubMed1995

Results of splenectomy performed on a group of 91 children.

In the period 1971-1990 91 children underwent splenectomies in the University Hospital of Nijmegen. The most important indications are hereditary spherocytosis, Hodgkin's disease and very severe immune thrombocytopenic purpura (ITP). Splenectomy after a traumatic rupture of the spleen has become less frequent: from 20% in 1971-1980 to 4% in 1981-1990. Short-term complications included thrombocytosis (84%), fever without an obvious cause (46%), which is quite regularly seen in patients suffering from Hodgkin's disease (48%), and infections of the respiratory tract in 10% of the patients. The platelet count shows a steady increase in the first nine post-operative days. No thromboembolic complications were seen. Based upon the literature there seems to be no reason at this moment for anti-platelet aggregation therapy when platelet counts are below 1000 x 10(9)/l. More information about long-term complications was obtained through a questionnaire completed by general practitioners. The morbidity through overwhelming post splenectomy infection (OPSI) is 3.8% (3/79), the mortality of OPSI is 2.5% (2/79). Underlying diseases, especially those which involve the immunological system as auto immune haemolytic anemia (AIHA), seem to play an important role in the possible development of OPSI (morbidity 2/11, 18%).

Adolescent↗
PubMed1981

Assay of an activity in the serum of patients with disorders of thrombopoiesis that stimulates formation of megakaryocytic colonies.

We have recently described an in vitro clonal assay system for human megakaryocyte-progenitor cells or megakaryocytic colony-forming units (CFU-M). Serum specimens from patients with quantitative platelet disorders were screened for the capacity to alter in vitro megakaryocyte-colony formation. Serum from 11 patients with hypomegakaryocytic thrombocytopenia significantly enhanced the formation of CFU-M-derived colonies (200 to 1840 per cent). Neither serum from eight patients with thrombocytopenia and normal or increased numbers of marrow megakaryocytes nor serum from 11 patients with thrombocytosis altered colony formation. This stimulatory activity has been termed megakaryocytic-colony-stimulating activity (Meg-CSA). The number of megakaryocytic colonies formed was directly proportional to the quantity of stimulatory serum added. Meg-CSA levels appeared to be inversely related to marrow megakaryocyte numbers. The variations in Meg-CSA levels that were detected in different disease states suggest that alterations in the production of this stem-cell regulator have physiologic importance.

Blood Platelet Disorders↗
PubMed1999

Safety profile of meropenem: a review of nearly 5,000 patients treated with meropenem.

Meropenem is a parenteral carbapenem that has been used clinically since 1994. Since the first review of its safety profile in 1995, the patient database has increased substantially. This new safety analysis includes data from 46 clinical trials in hospitalized patients with serious bacterial infections. The additional data comprise patients with lower respiratory tract and intra-abdominal infections, septicaemia and meningitis, and cancer patients with febrile neutropenia, and represents a group of more severely ill patients compared with the earlier review. In total, 4872 patients with 5026 meropenem treatment exposures were compared with 4642 patients treated with comparator agents (4752 exposures). Meropenem was administered most often by intravenous injection at 1g or 500 mg every 8 h. Meropenem-related adverse events most frequently reported were diarrhoea (2.3%), rash (1.4%), nausea/vomiting (1.4%) and injection site inflammation (1.1%). The most commonly reported meropenem-related laboratory adverse events were thrombocytosis (1.6%) and increased hepatic enzymes (1.5-4.3%). In meropenem-treated patients with meningitis, the incidence of seizures was low and none were drug related. In patients with infections other than meningitis, the incidence of seizures considered by the investigators to be related to meropenem was 0.08%. In general, the safety profile of meropenem was similar to that of the comparator agents. Withdrawals and deaths were similarly infrequent in the meropenem, cephalosporin and imipenem-cilastatin groups. Increased doses of meropenem were not associated with an increased incidence of adverse events. Meropenem was well tolerated in all patients, including children and patients with neutropenia. This new analysis supports the previous findings that meropenem has a favourable and acceptable safety profile.

Adult↗
PubMed2003

Effects of in vitro platelet activation on platelet derived nitric oxide production in healthy humans and in chronic myeloproliferative diseases with elevated platelet counts.

Intravascular EDRF-NO production is known to be impaired in some diseases, e.g., diabetes. This phenomenon may also contribute to the development of diabetic vascular disease. More recently the presence of NO synthase (ecNOS, iNOS) have been recognized in human platelets. Platelets produce NO only during activation, even though in minute amounts. This platelet derived NO seems to play an important physiological role, as it inhibits further platelet recruitment quite substantially. In the present report washed platelets isolated from healthy persons and patients with chronic myeloproliferative diseases (CMPD) were exposed to common and physiologically relevant activators (i.e., thrombin, collagen, epinephrine etc.). These tests were carried out in 20 healthy volunteers and 15 patients suffering from myeloproliferative disorders associated with thrombocytosis. As a consequence of pathological platelet function observed in CMPD, the in vitro platelet NO response is impaired in the patient group. One may assume, that reduced platelet NO response, at least in part, may contribute to platelet hyperfunction, angiopathy and thrombotic complications in some cases of CMPD.

Adult↗
PubMedDate not supplied

Toxicity and side effects of hydroxyurea used for primary thrombocythemia.

Over the last 20 years a vast array of data has been accumulated on the efficacy of hydroxyurea (HU) in patients with Philadelphia-negative myeloproliferative disorders (MPD). However, several side effects have been described as well. Besides many anecdotal reports, no evaluation of their prevalence and type exists in large series of treated patients. We report here the side effects of HU in a retrospective, single institution, cohort study of 152 patients suffering from MPD with thrombocytosis (median follow-up 8.13 years). In 6.5% of patients drug failure was registered. Unwanted side-effects (five symptomatic macrocytic anemia, two fever reactions, two allergic reactions, four cases each of leg painful ulcers, three acute leukemia or myelodysplasia) induced to withdraw therapy in 16 patients. Three cases of nail pigmentation were observed. In our experience, HU showed to be an effective and safe drug in most patients with MPD. Prompt recognition of side effects, which have been mostly minor and rapidly subsiding on drug withdrawal, is in any case crucial to avoid more severe complications.

Adult↗