Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cellular and physiological responses to changes in dioxygen levels in metazoans are mediated via the posttranslational oxidation of hypoxia-inducible transcription factor (HIF). Hydroxylation of conserved prolyl residues in the HIF-alpha subunit, catalyzed by HIF prolyl-hydroxylases (PHDs), signals for its proteasomal degradation. The requirement of the PHDs for dioxygen links changes in dioxygen levels with the transcriptional regulation of the gene array that enables the cellular response to chronic hypoxia; the PHDs thus act as an oxygen-sensing component of the HIF system, and their inhibition mimics the hypoxic response. We describe crystal structures of the catalytic domain of human PHD2, an important prolyl-4-hydroxylase in the human hypoxic response in normal cells, in complex with Fe(II) and an inhibitor to 1.7 A resolution. PHD2 crystallizes as a homotrimer and contains a double-stranded beta-helix core fold common to the Fe(II) and 2-oxoglutarate-dependant dioxygenase family, the residues of which are well conserved in the three human PHD enzymes (PHD 1-3). The structure provides insights into the hypoxic response, helps to rationalize a clinically observed mutation leading to familial erythrocytosis, and will aid in the design of PHD selective inhibitors for the treatment of anemia and ischemic disease.
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PMID:Cellular oxygen sensing: Crystal structure of hypoxia-inducible factor prolyl hydroxylase (PHD2). 1678 14

Most hemodialysis patients exhibit renal anemia mainly due to erythropoietin deficiency as a result of impaired erythropoetin production in the kidney. However, erythrocytosis in patients with renal failure requiring hemodialysis is extremely rare. We report the development of erythrocytosis in a patient with a polycystic kidney disease on hemodialysis for 13 years. She had erythrocytosis with increased serum erythropoietin levels despite severe secondary hyperparathyroidism, which is known to depress erythrocytosis. Since neither renal disease (renal cell carcinoma) nor extrarenal diseases (hypoxia, hepatoma, cerebellar diseases) linked with erythropoietin production could be proven, this case might be one with inappropriate idiopathic erythropoietin production after 13 years of hemodialysis, the longest duration of dialysis in the literature before erythrocytosis was observed.
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PMID:Erythrocytosis in a patient on hemodialysis for thirteen years. 1728 2

Arterial hypertension develops in up to 80% of renal transplant recipients. Uncontrolled hypertension induces left ventricular hypertrophy, heart failure and death, but also promotes deterioration of allograft function. Cadaveric transplantation, delayed graft function, renal artery stenosis, presence of native kidneys, increased body weight and therapy with calcineurin inhibitors and steroids have been associated with an increased incidence of hypertension after kidney transplantation. Cyclosporine increases both systemic and renal vascular resistance, enhances sympathetic activation, endothelin production and, possibly, decreases vascular relaxation by decreasing the generation of nitric oxide. Tacrolimus has less pronounced prohypertensive role after renal transplantation. Corticosteroids contribute to the development of hypertension, since their withdrawal results in a significant decrease of blood pressure in the majority of patients. Renal artery stenosis occurs in almost 12% of hypertensive renal transplant recipients. It is a correctable cause of hypertension, and for this reason should be investigated in all suspected patients. Doppler ultrasonography is used as the screening method that is highly sensitive and specific in the hands of a well-experienced investigator. However, dependence of the method on the experience of the investigator is its major drawback. Magnetic resonance angiography and spinal computed tomography angiography are useful noninvasive methods, but arteriography remains a method for establishing the definitive diagnosis. Percutaneous balloon angioplasty, with or without placement of the stent, is successful in the majority of patients, but with a high incidence of restenoses (20%). Surgery is indicated for stenoses that cannot be treated with angioplasty or that recur. Auto-transplantation of the kidney with complex stenoses of graft arteries is useful in selected cases. Posttransplant hypertension should be aggressively treated to prevent the development of end-organ damage. Every effort should be invested in reducing immunosuppression when appropriate, together with salt restriction and weight reduction. Calcium channel blockers have good antihypertensive properties accompanied with minimization of cyclosporine-induced renal vasoconstriction. Angiotensin-converting enzyme inhibitors (ACEi) should be used in patients with proteinuria. Renal function should be carefully monitored after their introduction since they may cause transitory deterioration of glomerular filtration and/or hyperkaliemia. ACEi can induce anemia in renal transplant recipients, side effect that is often used in the treatment of posttransplant erythrocytosis. All other antihypertensive drugs could be used, with minoxidil being the most potent one. Patients with resistant hypertension should be investigated for the presence of renal artery stenosis. After exclusion of rejection, renal artery stenosis and recurrent disease, in cases of severe hypertension, native kidneys laparoscopic nephrectomy should be considered.
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PMID:[Arterial hypertension in renal transplant recipients]. 1836 9

An increasing understanding of the process of erythropoiesis raises some interesting questions about the pathophysiology, diagnosis and treatment of anemia and erythrocytosis. The mechanisms underlying the development of many of the erythrocytoses, previously characterised as idiopathic, have been elucidated leading to an increased understanding of oxygen homeostasis. Characterisation of anemia and erythrocytosis in relation to serum erythropoietin levels can be a useful addition to clinical diagnostic criteria and provide a rationale for treatment with erythropoiesis stimulating agents (ESAs). Recombinant human erythropoietin as well as other ESAs are now widely used to treat anemias associated with a range of conditions, including chronic kidney disease, chronic inflammatory disorders and cancer. There is also heightened awareness of the potential abuse of ESAs to boost athletic performance in competitive sport. The discovery of erythropoietin receptors outside of the erythropoietic compartment may herald future applications for ESAs in the management of neurological and cardiac diseases. The current controversy concerning optimal hemoglobin levels in chronic kidney disease patients treated with ESAs and the potential negative clinical outcomes of ESA treatment in cancer reinforces the need for cautious evaluation of the pleiotropic effects of ESAs in non-erythroid tissues.
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PMID:Pathophysiology of anemia and erythrocytosis. 1765 1

The PO2 at this site where erythropoietin release is regulated should vary only when the hemoglobin concentration changes in capillary blood. The kidney cortex is an ideal location for this O2 sensor for four reasons. First, it extracts a small proportion of the oxygen that is delivered in each liter of blood; this makes the PO2 signal easier to recognize. Second, there is a constant ratio of the work performed (consumption of O2) to the renal blood flow rate (delivery of O2). Third, the high renal blood flow rate improves diffusion of O2 from capillaries to this O2 receptor. Fourth, a high renal cortical PCO2 prevents an additional shift of the O2:hemoglobin dissociation curve by other factors from being a confounding variable. This suggests that the GFR and the renal blood flow rate should be examined in patients with unexplained anemia or erythrocytosis.
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PMID:Properties permitting the renal cortex to be the oxygen sensor for the release of erythropoietin: clinical implications. 1769 26

Chronic lung disorders are usually associated with a hypoxia driven increase in red cell mass. However, patients with cystic fibrosis (CF) often have normal or decreased haemoglobin levels. The present prospective observational study in cystic fibrosis patients was performed to determine which factors were involved in alterations in the hematopoetic response to corresponding arterial oxygen pressure. Sixty adult patients (age 21-51) with stable CF were included. They all had vitamin A, D, E, and K but no vitamin B12 supplementation. Twenty-five patients were on oral Fe(2+) (100 mg/day). Resting arterial blood gases, lung function, complete blood counts, parameters of iron status, CRP, sputum microbiology and serum erythropoietin were measured at recruitment and after 3 and 6 months. Patients had varying degrees of pulmonary functional impairment and 9% were hypoxemic (arterial oxygen pressure <60 mm Hg). Low-grade systemic inflammation (CRP > 0.5 mg/dl) was present in 40% of the patients, who all had bacterial colonization. None of the patient had erythrocytosis and 12 patients had anemia. There was no significant difference in iron status between patients with or without chronic iron supplementation and erythropoietin levels were normal. During the 6 months observation period no significant changes occurred. The patients exhibited an impaired erythropoietic response to hypoxemia with normal or low hematocrit in spite of chronic lung disease which might be caused by chronic inflammation associated with CF. Linear multivariate regression analysis revealed CRP levels but neither iron substitution, nor erythropoietin levels nor lung function parameters as independent determinant of haemoglobin levels. CF may be associated with anemia of variable severity as expression of the chronic inflammation present in these patients. The therapeutic consequences are to treat the underlying inflammation rather than to supplement iron.
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PMID:Lung disease severity, chronic inflammation, iron deficiency, and erythropoietin response in adults with cystic fibrosis. 1794 83

Many patients with anemia fail to respond to treatment with erythropoietin (Epo), a commonly used hormone that stimulates erythroid progenitor production and maturation by human BM or by murine spleen. The protein product of growth arrest-specific gene 6 (Gas6) is important for cell survival across several cell types, but its precise physiological role remains largely enigmatic. Here, we report that murine erythroblasts released Gas6 in response to Epo and that Gas6 enhanced Epo receptor signaling by activating the serine-threonine kinase Akt in these cells. In the absence of Gas6, erythroid progenitors and erythroblasts were hyporesponsive to the survival activity of Epo and failed to restore hematocrit levels in response to anemia. In addition, Gas6 may influence erythropoiesis via paracrine erythroblast-independent mechanisms involving macrophages. When mice with acute anemia were treated with Gas6, the protein normalized hematocrit levels without causing undesired erythrocytosis. In a transgenic mouse model of chronic anemia caused by insufficient Epo production, Gas6 synergized with Epo in restoring hematocrit levels. These findings may have implications for the treatment of patients with anemia who fail to adequately respond to Epo.
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PMID:Role of Gas6 in erythropoiesis and anemia in mice. 1818 50

Besides the immunological mediated damage on the graft, the intrarenal renin-angiotensin system (RAS) is viewed as an additional mechanism in the development and progression of chronic allograft injury. RAS blocking agents efficiently control post-transplant hypertension and are useful to reduce proteinuria and for treating post-transplant erythrocytosis. However, RAS blockade is associated with some potentially relevant adverse events as hyperkalemia, anemia, and even to a decline in renal function. There are consistent experimental data showing that RAS blockade has a therapeutic effect on chronic allograft injury. Some clinical studies have shown that RAS blockade reduces transforming growth factor-beta1 and other markers of fibrosis but, up to now, there is not convincing evidence supporting that RAS blockade has further benefit on the progression of chronic allograft injury in comparison with other antihypertensive interventions. Theoretically, RAS blockade may also improve cardiovascular disease, which constitutes the main cause of mortality and morbidity in renal allograft recipients. Nevertheless, to date there is lack of evidence for supporting that RAS blockade improves neither graft nor patient survival in comparison with other antihypertensive drugs. Randomized, prospective, double blind, placebo-controlled trials with enough sample size and follow-up are needed to address the potential role of RAS blockade to improve graft and patient outcome. Meanwhile, we should empirically balance case to case the pros and cons of RAS blockade in renal transplantation.
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PMID:The renin angiotensin system blockade in kidney transplantation: pros and cons. 1826 74

Numerous studies using erythropoietin (EPO) gene delivery vectors, either viral or nonviral, have shown uncontrolled EPO expression leading to transient or sustained erythrocytosis and, more recently, severe autoimmune anemia. Therefore, there is a need to develop other EPO gene delivery systems that allow sustained and adjustable expression of EPO. We have examined a new approach of delivering plasmid encoding mouse EPO cDNA into mouse skeletal muscle, using an amphiphilic block copolymer. Repeated injections of low doses of block copolymer-EPOcDNA formulations increased hematocrit in a dose-dependent manner for more than 9 months, without any initial overshoot. Low doses of block copolymer-EPOcDNA formulations prevented autoimmune anemia in immunocompetent Swiss mice and prevented or reversed chronic anemia in an acquired mouse model of renal failure. We conclude that repeated injections of low doses of block copolymer-DNA formulations that do not induce (1) inflammation at the injection site, (2) overexpression of EPO, or (3) the production of anti-EPO neutralizing auto-antibodies hold promise for in vivo expression of therapeutic proteins, in particular for systemic delivery.
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PMID:Therapy of anemia in kidney failure, using plasmid encoding erythropoietin. 1834 22

Recipients of renal allografts are surviving longer and, consequently, may experience a variety of complications related not only to the transplanted kidney, but also to the hematopoietic system. Common hematologic complications in the renal transplant patient include abnormalities of one cell line, such as post-transplantation erythrocytosis or anemia, that are often treatable with simple measures. Conversely, pathologies involving the leukocyte and platelet population often exist in the context of pancytopenia, which may be a manifestation of systemic infection (e.g., cytomegalovirus, human herpesvirus 8) or malignancy (post-transplantation lymphoproliferative disorders). Uncommon, but life-threatening, processes complicating renal transplantation include hepatosplenic gammadelta T-cell lymphoma and viral-induced hemophagocytic syndrome, both of which are associated with severe pancytopenia and, often, death. Since this patient population is often managed in a multidisciplinary fashion by nephrologists, infection specialists, transplant surgeons, hematologists, and internal medicine physicians, a succinct review of this topic is warranted.
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PMID:Hematologic abnormalities following renal transplantation. 1930 Nov 40


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