Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0032463 (polycythemia vera)
3,374 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The vascular complications in patients with polycythemia vera are microvascular circulatory disturbances typical of thrombocythemia including erythromelalgia, peripheral ischemia, atypical cerebral ischemic attacks, and major arterial and venous thrombotic events. These are positively related to hematocrits due to the increased red cell mass and its concomitant increased whole blood viscosity. Phlebotomy does not prevent the aspirin-responsive microcirculatory circulation disturbances in polycythemia vera because thrombocythemia (platelet count > 400 x 10(9)/L) persists. The risk of major vascular ischemic episodes in poorly controlled polycythemia vera at hematocrits between 0.45 and 0.50 is rather high. The risk of vascular complications in polycythemia vera is best controlled by maintaining the hematocrit at less than 0.45 and the platelet count below 400 x 10(9)/L. The microvascular syndrome associated with thrombocythemia in early stage polycythemia vera in remission by phlebotomy is easily and best controlled by low-dose aspirin (50 to 100 mg) or by selective reduction of platelet count to normal with low-dose myelosuppressive agents. The potential leukemogenic myelosuppressive agents busulfan and hydroxyurea and the nonleukemogenic cytosine interferon-alpha have proven to be effective in the control of the proliferative phase of polycythemia vera. However, data on the natural history of polycythemia vera and the best treatment modality of the various stages of myeloproliferative disease are still lacking.
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PMID:Erythromelalgia and vascular complications in polycythemia vera. 938 3

Cardiac vagal neurons play a critical role in the control of heart rate and cardiac function. These neurons, which are primarily located in the nucleus ambiguus (NA) and the dorsal motor nucleus of the vagus (DMNX), dominate the neural control of heart rate under normal conditions. Cardiac vagal activity is diminished and unresponsive in many disease states, while restoration of parasympathetic activity to the heart lessens ischemia and arrhythmias and decreases the risk of sudden death. Recent work has demonstrated that cardiac vagal neurons are intrinsically silent and therefore rely on synaptic input to control their firing. To date, three major synaptic inputs to cardiac vagal neurons have been identified. Stimulation of the nucleus tractus solitarius evokes a glutamatergic pathway that activates both NMDA and non-NMDA glutamatergic postsynaptic currents in cardiac vagal neurons. Acetylcholine excites cardiac vagal neurons via three mechanisms, activating a direct ligand-gated postsynaptic nicotinic receptor, enhancing postsynaptic non-NMDA currents, and presynaptically by facilitating transmitter release. This enhancement by nicotine is dependent upon activation of pre- and postsynaptic P-type voltage-gated calcium channels. Additionally, there is a GABAergic innervation of cardiac vagal neurons. The transsynaptic pseudorabies virus that expresses GFP (PRV-GFP) has been used to identify, for subsequent electrophysiologic study, neurons that project to cardiac vagal neurons. Bartha PRV-GFP-labeled neurons retain their normal electrophysiological properties, and the labeled baroreflex pathways that control heart rate are unaltered by the virus.
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PMID:Synaptic and neurotransmitter activation of cardiac vagal neurons in the nucleus ambiguus. 1145 81

Bilateral massive adrenal swelling (BAS) on computed tomography (CT) scan with no enhancement after injection of intravenous contrast media has been observed in two completely different clinical settings. On the one hand, BAS is the result of ischemic necrosis and subsequent hemorrhagic infarction in patients with sepsis and hypotension in critically ill situations. On the other hand, BAS is the result of microvascular thrombosis, ischemia, and secondary inflammatory swelling in the setting of thrombotic conditions such as antiphospholipid syndrome (APS), heparin-induced thrombocytopenia and thrombosis (HITT), and thrombocythemia. In this study we present evidence that the etiology of unilateral or BAS in reported cases of essential thrombocythemia (ET) and polycythemia vera (PV) is similar to the etiology of microvascular circulation disturbances in thrombocythemia caused by platelet-mediated inflammation and thrombosis in the peripheral, cerebral, and/or coronary endarterial microvascular circulation.
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PMID:Bilateral adrenal swelling as a cause of chest, back, and upper abdominal pain in essential thrombocythemia and polycythemia vera is due to microvascular ischemic thrombosis rather than to hemorrhage. 1248 64

Erythromelalgia is the main, pathognomonic and presenting symptom in patients with essential thrombocythemia and thrombocythemia associated with polycythemia vera. Complete relief from erythromelalgic and acrocyanotic pain is obtained with the cyclooxygenase inhibitors aspirin and indomethacin, but not with sodiumsalicylate, dipyridamol, sulfinpyrozone and ticlopedine. Thus, cyclooxygenase metabolites are necessary for erythromelalgia to develop. Local platelet consumption in erythromelalgic areas became evident by the demonstration of arteriolar fibromuscular intimal proliferation and occlusions by platelet-rich thrombi in skin biopsies, by the findings of shortened platelet survival times, significant higher levels of platelet activation markers beta-thromboglobulin, thrombomoduline and increased urinary thromboxane B2 excretion in thrombocythemia patients suffering from erythromelalgia. Aspirin treatment of erythromelalgia in thrombocythemia patients resulted in the disappearance of the erythromelalgic, thrombotic signs and symptoms, correction of the shortened platelet survival times, and a significant reduction of the increased levels of beta-TG, PF4, TM and urinary TxB2 excretion to normal. Erythromelalgia is frequently preceded or followed by atypical transient neurologic, ocular or coronary ischemic symptoms, which specifically respond to low-dose aspirin or reduction of platelet counts to normal. The broad spectrum of acropareshesias, erythromelalgia and acrocyanotic ischemia together with the episodic and transient atypical TIAs and ocular or coronary ischemic symptoms are caused by spontaneous activation and aggregation of hypersensitive platelets in the end-arterial microvasculature involving the peripheral, cerebral and coronary circulation of thrombocythemia patients. These microvascular circulation ischemic disturbances in thrombocythemia vera already occur at platelet counts in excess of 400 x 10(9) l(-1). Low-dose aspirin is highly effective and safe in the cure and prevention of thrombotic and ischemic events and does not elicit bleedings at platelet counts below 1000 x 10(9) l(-1). Spontaneous hemorrhages usually occur at very high platelet counts far in excess of 1000 x 10(9) l(-1) (HT) due to an acquired von Willebrand factor deficiency at increasing platelet counts. At platelet counts between 1000 and 2000 x 10(9) l(-1), thrombosis and bleeding (ETT and HT) frequently occur in sequence or paradoxically and low-dose aspirin does prevent thrombotic complications but aggravates or may elicit bleeding symptoms. Reduction of the platelet count to below 1000 x 10(9) l(-1) by platelet lowering agents usually results in the disappearance of the bleeding tendency and improvement of the von Willebrand syndrome, but the thrombotic tendency persists as long as platelet counts are above the upper limit of normal.
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PMID:Platelet-mediated microvascular inflammation and thrombosis in thrombocythemia vera: a distinct aspirin-responsive arterial thrombophilia, which transforms into a bleeding diathesis at increasing platelet counts. 1278 99

We investigated endothelial and in vivo platelet activation in a cohort of 52 patients with essential thrombocythemia (ET) and polycythemia vera (PV) before and after cytoreductive treatment, 22 healthy controls, and 17 patients with acute cerebrovascular ischemia (ACVI) and normal platelet counts. We measured platelet expression of CD62P and CD63 antigens and levels of soluble vascular cell adhesion molecule 1 (sVCAM-1). We found increased in vivo platelet activation in all patients with ET and PV, both before and after cytoreductive treatment, compared with controls. In patients with arterial thrombosis, platelet expression of CD62P, and in patients with erythromelalgia, expression of both markers was higher compared with expression in patients without thrombotic complications. In patients with ET and PV before and after treatment, sVCAM-1 expression was increased compared with expression in controls but also compared with expression in patients with ACVI and normal platelet counts. In patients with arterial thrombosis and erythromelalgia, in vivo platelet activation correlated with the level of sVCAM-1. Our findings indicated that in vivo platelet activation reflects intrinsic platelet defects in patients with ET and PV, persists after cytoreductive treatment, and results in endothelial damage, probably through release of angiogenic factors and/or activation of white blood cells.
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PMID:Markers of endothelial and in vivo platelet activation in patients with essential thrombocythemia and polycythemia vera. 1516 94

A 53-year-old male patient complained of the pain with bilateral hip area and right hip joint and underwent emergency arthroscopy and drainage. Twenty-eight years before, he had suffered from gout and from his abnormal increase of blood cells was diagnosed as polycythemia vera. The laboratory examination at admission showed a marked increase of hemoglobin (17.7 g x dl(-1)) and hematocrit (69.5%). Immediately before induction of anesthesia, 1000 ml of phlebotomy was performed with large fluid infusion. After induction of anesthesia and oro-tracheal intubation, electrocardiogram (ECG) suddenly showed ventricular fibrillation (Vf). Defibrillation was applied and the ECG recovered to sinus rhythm, but 30 min later, ECG showed Vf, again. The increased blood viscosity with polycythemia might have induced coronary ischemia and fatal arrhythmia in the patient. Vigourous hemodilution before surgery should have been performed as prophylactic management of the cardiac episodes in this patient.
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PMID:[Ventricular fibrillation during induction of anesthesia in a patient with polycythemia vera]. 1713 99

Vascular manifestations are the main clinical complication of essential thrombocythemia (ET). They include arterial thrombosis (30-40% of patients), venous thrombosis (5%), and ischemia due to microcirculatory disorders. Their incidence is highest at disease onset and diminishes gradually thereafter. The pathophysiology of ET involves dysmegakaryocytopoiesis, leading to platelet, leukocyte and vascular endothelial cell activation. The recent discovery of the V617F mutation of the JAK2 tyrosine kinase in 50-60% of patients with ET defined a new subgroup resembling polycythemia vera. This review examines biological findings and their correlation with the risk of thrombosis. Until now, stratification of the vascular risk has relied on a clinical case-control study showing that thrombotic and vascular complications are more frequent in patients over 60 and those with a history of thrombosis. These criteria, along with a rapid increase in thrombocytosis (>1500 G/L) leading to an increase in the bleeding risk, define a high-vascular-risk subgroup of patients warranting cytoreductive therapy. Although many biological markers of dysmegakaryocytopoiesis and cellular hyperactivation have been linked to an increase in the thrombotic risk, none is available for large-scale prediction of an intermediate vascular risk. The role of the JAK2 V617F mutation itself is controversial. Whatever the ET subgroup, antiplatelet therapy is largely used, based on the results of the ECLAP prospective controlled trial that showed a statistically significant reduction in thrombotic complications in patients receiving aspirin for polycythemia vera, a very similar myeloproliferative disorder.
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PMID:[Vascular complications of essential thrombocythemia]. 1807 51

The red cell expansion in polycythemia vera (PV) causes hyperviscosity affecting blood flow, which plays a major role in the pathogenesis of both microcirculatory disturbances and ultimately thromboses. Ischemia-modified albumin (IMA) is produced during an ischemic states and is present in blood in early and easily detectable levels. This study investigated whether IMA is a useful adjunct in the determination of ischemia in patients with PV, prior to them exhibiting clinical evidence of thrombotic complications. Blood IMA levels were determined in 20 PV patients and in 20 healthy individuals using a method described by Bar-Or. Mean IMA levels in the PV group were significantly higher than those of the control group (P<0.05). At the optimum cutoff point (0.193 absorbance units), the sensitivity and specificity of IMA were 80 and 100% to ischemia, respectively. In conclusion, IMA may be a valuable biochemical marker in predicting tissue ischemia in PV before the signs of vascular disturbances occur.
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PMID:Can ischemia-modified albumin be a valuable indicator of tissue ischemia in polycythemia vera? 2055 73

Inherited and acquired tendency to the formation of clots represents an important cause of morbidity and mortality for ischemic events in young people (aged between 40 and 50 years) that is more and more frequently identified. The haemostasis' disorders may happen on the venous or arterial side. Arterial thrombus is a 'white' thrombus, also called temporary thrombus. It consists of aggregate platelets only. On the contrary, venous thrombus is 'red' or permanent thrombus composed of platelets, red cells and fibrin. The first is the result of platelets' adhesion or aggregation. Instead, the permanent thrombus derives from the coagulant factors successively acting on 'white' thrombus. The different pathogenesis justifies both the distinction between 'hypercoagulability' and 'thrombophilia' and the different treatments employed. Antiphospholipid antibody syndrome, polycythemia vera, atrial fibrillation-acquired hyperhomocysteinemia, diabetes mellitus and myeloproliferative disease are the most frequent causes of acquired hypercoagulable state, prevalently responsible for deep venous thrombosis. Among the inherited forms, congenital hyperhomocysteinemia, factor V Leiden mutation, proteins C and S deficiency and antithrombin mutation are included. These may induce both venous and arterial acute events. Hyperhomocysteinemia can be congenital and acquired and is more correctly named as 'thrombophilia' rather than 'hypercoagulability'. That happens because it involves the platelets' aggregation rather than the coagulant cascade. The optimal treatment of thrombophilias consists of oral (warfarin) or injectable (heparins) anticoagulants. Direct thrombin inhibitors, platelet glycoprotein IIb/IIIa antagonists, and tissue factor inhibitors also appear to be some attractive approaches. For acquired forms, treatments of their aetiologies must also be carried out. For acquired hyperhomocysteinemia, both antiplatelets' therapy (aspirin + clopidogrel) and new direct thrombin inhibitors (as dabigatran) could be considered. Finally, as secondary prevention of an arterial acute event (stroke, IMA or peripheral ischemia) due to hyperhomocysteinemia, lifetime dual antiplatelets' therapy should be used.
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PMID:Some considerations about the hypercoagulable states and their treatments. 2134 57

One of the complications of polycythemia vera (PV) can be acute thrombotic occlusion. The severity and prolonged duration of this condition can lead to nerve damage. In this case a 34-year-old male had thrombotic occlusions of the popliteal artery, resulting in chronic limb ischemia, which was treated with thrombectomy and amputation of one digit. The administered therapy consisted of hydroxyurea, analgesics, antidepressants and acetylsalicylic acid. When the patient was admitted he suffered from ischemic pain, he had developed an ulcer on his big toe and he was emotionally unstable, with suicidal thoughts. The patient was treated with 14 hyperbaric oxygen (HBO2) treatments in total. There was evident paint relief after four treatments and healing of the ulcerous tissue after three weeks. During the patient's medical examination eight months after the treatment, his condition was still satisfactory, with no presence of pain, ulcer or signs of depression, and with no changes in hemodynamics. This case provides additional evidence to the data for HBO2 use in ischemic pain management.
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PMID:Hyperbaric oxygen therapy in treating post-ischemic pain caused by polycythemia vera complications: a case report. 2674 60


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