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Testing the excitability of axons can provide insights into the ionic mechanisms underlying the pathophysiology of axonal dysfunction in human neuropathies and motor neuron diseases. Threshold tracking, which was developed in the 1990's, non-invasively measures a number of axonal excitability indices, which depend on membrane potential and on the Na+ and K+ conductances. This paper reviews recent advances in ionic-pathophysiological studies in human subjects in vivo. Membrane potential of human axons can be estimated, because most of the ion channels expressed on the axolemma are voltage-dependent, and patterns of changes in multiple excitability indices can suggest whether axons are depolarized or hyperpolarized. This has been clearly demonstrated in a single patient with acute hypokalemia (hyperpolarization) and patients with chronic renal failure (depolarization due to hyperkalemia). Muscle cramps/fasciculations arise from hyperexcitability of the motor axons. The enhanced excitability can result from altered ion channel function; an increase in persistent Na+ conductance, a decrease in accommodative K+ conductance, and focal membrane depolarization, all of which increase excitability, have been demonstrated in amyotrophic lateral sclerosis or other disorders affecting lower motor neurons. Patients with demyelinating neuropathy often complain of muscle fatigue. During voluntary contraction, the activation of the electrogenic Na+-K+ pump and resulting membrane hyperpolarization can cause activity-dependent conduction block when the safety factor for impulse transmission is critically reduced. Studies of ion-channel pathophysiology in human subjects have recently begun. Investigating ionic mechanisms is of clinical relevance, because once a specific ionic conductance is identified, blocking or activating it may provide a new therapeutic option for a variety of neuromuscular diseases.
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PMID:Axonal ionic pathophysiology in human peripheral neuropathy and motor neuron disease. 1618 Oct 85

Erythropoietin is a hypoxia-induced hormone that is a major regulator of normal erythropoiesis. Over the last decade, the production of recombinant human erythropoietin has revolutionized the treatment of anemia associated with chronic renal failure, and has led to a greater understanding of anemia pathophysiology and to the elucidation of the interactions of erythropoietin, iron, and erythropoiesis. Anemia has been shown to be independently associated with increased mortality and disease progression. Potential survival benefits associated with correction of anemia have expanded considerably the indications of erythropoietin use in various patient populations and are leading to consideration of earlier, more aggressive treatment of mild to moderate anemia. The results of such treatment are promising in a variety of new clinical settings, including anemia associated with congestive heart failure. Furthermore, the erythropoietin receptor is widely distributed in the cardiovascular system, including endothelial cells, smooth muscle cells and cardiomyocytes and preclinical studies have established erythropoietin to be a pleiotropic cytokine with anti-apoptotic activity and tissue-protective actions in the cardiovascular system, beyond correction of hemoglobin levels. Despite some potential adverse effects, such as hypertension, and the occurrence of erythropoietin resistance, early studies in heart failure patients with anemia suggest that erythropoietin therapy is safe and effective in reducing left ventricular hypertrophy, enhancing exercise performance and increasing ejection fraction. Anemia is found in about one-third of all cases of congestive heart failure (CHF). The most likely common cause is chronic renal insufficiency, which is present in about half of all CHF cases. However, anemia can occur in CHF without renal insufficiency and is likely to be due to excessive cytokine production. The anemia itself can worsen cardiac function, both because it causes cardiac stress through tachycardia and increased stroke volume, and because it can cause a reduced renal blood flow and fluid retention, adding further stress to the heart. Long-standing anemia of any cause can cause left ventricular hypertrophy, which can lead to cardiac cell death through apoptosis and worsen CHF. Therefore, a vicious circle, cardio-renal anemia syndrome, is set up wherein CHF causes anemia, and the anemia causes more CHF and both damage the kidneys worsening the anemia and the CHF further and increasing mortality. There is now evidence that early correction of the CHF anemia with subcutaneous erythropoietin and intravenous iron improves shortness of breath and fatigue, cardiac function, renal function and exercise capacity, reducing the need for hospitalization and improving quality of life. In the present review we discuss the data on current clinical use of erythropoietin in cardiovascular disease, with the main focus on the treatment of congestive heart failure, and summarize the advances and progress made in the understanding of the hematopoietic and pleiotropic effects of erythropoietin in the cardiovascular system.
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PMID:Erythropoietin in heart failure and other cardiovascular diseases: hematopoietic and pleiotropic effects. 1624 29

(1) Current treatments for anaemia in patients receiving cancer chemotherapy include blood transfusion and epoetin alfa and beta. These epoetins correct anaemia in 40% to 65% of patients and reduce the number of patients who require transfusions during the second and third months of treatment by 12-35% in absolute terms. (2) Darbepoetin alfa is slightly more glycosylated than epoetin alfa and beta. It is no more effective than these two drugs in chronic renal failure. Darbepoetin alfa is now approved for the treatment of anaemia in patients who are receiving chemotherapy for non myeloid malignancies. (3) Two placebo-controlled dose-finding studies and two placebo-controlled trials involving nearly 1000 patients in total have shown that darbepoetin alfa decreases the number of transfused patients by 17-25% in absolute terms, and that it probably reduces fatigue. However, one-quarter of patients receiving darbepoetin were nonetheless transfused. (4) In the absence of reliable comparisons, there is no firm evidence that darbepoetin alfa is more effective than other epoetins. (5) According to relatively imprecise company reports, darbepoetin alfa increased the risk of thromboembolic events during clinical trials (6% versus 3%), including pulmonary embolism (1.3% versus 0%); the company also states that darbepoetin alfa does not increase the risk of arterial hypertension, a classical effect of epoetin that is mentioned in the summary of product characteristics (SPC). Placebo-controlled trials and dose-finding studies show no impact on the outcome of cancer, but follow-up is limited and a negative effect cannot be ruled out. The company states that no cases of erythroblastopenia have occurred among more than 70 000 treated patients. (6) According to the SPC, darbepoetin alfa can be given once a week. However, the optimal epoetin dosing schedule is unknown. Epoetin therapy takes several weeks to correct anaemia, whereas transfusion is immediately effective. (7) In practice, darbepoetin alfa seems a little easier to administer than epoetin alfa or beta, but the advantages and disadvantages of these drugs as compared with blood transfusion are not entirely clear.
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PMID:Darbepoetin alfa: new indication/new dosage. No proven advantage in chemotherapy-induced anaemia. 1628 72

Anemia in cancer patients undergoing treatment is common and can cause debilitating symptoms such as fatigue and reduced exercise tolerance. The introduction of recombinant human erythropoietin represents a potential improvement in the treatment of this condition. Clinical studies in patients with solid tumors and nonmyeloid hematologic malignancies have convincingly shown an improvement in mean hemoglobin concentration, a reduction in transfusion requirement along with an improvement in quality of life scores, although an effect on survival is less clear. In myeloid disorders such as myelodysplasia, response to single-agent recombinant human erythropoietin is disappointing but significant synergism with granulocyte colony stimulating factor has been demonstrated and different dosing regimens may also improve response. Unfortunately, a significant proportion of patients remain refractory to treatment. Efforts have been made to identify treatable causes of erythropoietin refractoriness, such as functional iron deficiency, and concomitant intravenous iron supplementation does appear to improve response rates. The search for pretreatment factors that predict response has been largely disappointing, although a promising model for myelodysplasia has been developed that awaits large-scale evaluation. Recombinant human erythropoietin is well tolerated, although there were concerns in the late 1990s due to a rising incidence of pure red cell aplasia in chronic renal failure patients treated with subcutaneous Eprex (Ortho Biologics) in Europe. Since potentially contributory manufacturing processes have been identified and corrected, the incidence of this complication has been falling.
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PMID:Epoetin alfa: basic biology and clinical utility in cancer patients. 1633 85

Patients with chronic renal failure (CRF) often have signs and symptoms related to fluid and electrolyte disturbances, anemia, malnutrition, bone disease, and gastrointestinal problems. Vascular and neurologic impairment in particular remain an important source of morbidity and mortality in this vulnerable patient population. Sagliker syndrome is a novel syndrome that was recently described in 2004 in patients with CRF and severe and late secondary hyperparathyroidism who suffered from severe skull and facial bone changes, particularly from uglifying human face appearances and neuropsychiatric disorders. The goal of this study was to assess neuropsychiatric manifestations occurring in CRF patients with Sagliker syndrome. Four female and 8 male patients with CRF on regular dialysis at the hemodialysis units of the Internal Medicine Departments around southern Turkey participated in the study. All patients underwent a clinical neurologic examination performed by the same neurologist. Neuropsychiatric signs and symptoms were found in all cases. The results showed that the most frequent neurologic manifestations in CRF patients with Sagliker syndrome were headache, polyneuropathy, cranial neuropathy, fatigue, and psychiatric disorders.
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PMID:Neurologic manifestations in Sagliker syndrome: uglifying human face appearance in severe and late secondary hyperparathyroidism in chronic renal failure patients. 1682 26

Patients with high fever and multiorgan involvement were investigated for the determination of frequency, clinical course and complications of leptospirosis in Istanbul. Leptospirosis was determined in 22 cases among the 35 hospitalized patients that were pre-diagnosed as leptospirosis according to 'Probable Leptospirosis Diagnosis and Follow-up' form. Among the leptospirosis cases 19 were male and 16 were military staff. Mean age was 35.6 y. Dark field examination (DFE), latex agglutination test (LAG), ELISA IgM, leptospirosis culture (LC) and microscopic agglutination test (MAT) were performed to confirm the diagnoses. The most frequent initial symptoms and findings were fever, fatigue, headache, nausea-vomiting and increased muscle sensitivity. Jaundice was noted only in 2 cases. A 74-y-old female patient died after the recurrence of the disease with severe rhabdomyolysis and pulmonary failure. Sagittal sinus thrombosis, perimyocarditis and chronic renal failure were major complications in another 3 patients. ELISA IgM, LC, DFE, LAG and MAT tests were positive in 68, 72, 82, 100 and 100% of the patients, respectively. As a conclusion, diagnosis of leptospirosis is usually overlooked. Clinical awareness, use of probable leptospirosis diagnosis forms and the application of different laboratory methods in the diagnosis of suspected cases may offer the chance to diagnose the leptospirosis accurately.
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PMID:Leptospirosis in Istanbul, Turkey: a wide spectrum in clinical course and complications. 1700 27

Mesalazine is a first-line drug in pediatric inflammatory bowel disease, and is effective as primary treatment and maintenance therapy. It's usually well tolerated, but various side effects have been described. A 15-year-old female with ulcerative colitis developed polyuria, polydipsia, vomiting, and fatigue. She was receiving mesalazine (500 mg, thrice daily, p.o.) and prednisolone for 4 months. She was detected as acute tubular injury as she had dehydration, acidosis, hypostenuria, hematuria, proteinuria, low levels of potassium, uric acid and bicarbonate. These findings were attributed to interstitial nephritis as a side effect of mesalazine, however as renal biopsy was disapproved by the parents, it was not confirmed. After discontinuation of mesalazine her renal tubular functions improved. Potassium and phosphorus supplements were stopped after 7 months, although she had to continue bicarbonate supplementation. We conclude that regular renal screening is important in patients receiving 5-ASA therapy to prevent rare but serious complications, such as interstitial nephritis sometimes leading to chronic renal failure.
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PMID:Acute tubular injury associated with mesalazine therapy in an adolescent girl with inflammatory bowel disease. 1740 67

A case of colchicine-induced rhabdomyolysis is reported. A 79-year-old man with ischemic heart disease, chronic atrial fibrillation, chronic renal failure, hypothyroidism, and gout arthritis was hospitalized because of fatigue, myalgia, and leg weakness, shortly after starting treatment with colchicine. Investigation confirmed the diagnosis of rhabdomyolysis, and discontinuation of colchicine resulted in resolution of clinical and biochemical features of rhabdomylysis. Colchicine-induced rhabdomyolysis is a rare complication, and the postulated mechanisms and risk factors for this severe complication are discussed.
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PMID:Colchicine-induced rhabdomyolysis. 1761 11

Juvenile systemic lupus erythematosus (JSLE) represents 15-20% of all SLE cases. The leading presenting symptoms of JSLE are constitutional and not specific such as fatigue, headache, weight loss or mood swings. They are also encountered in healthy adolescents, which explains frequent diagnosis delay. The frequency of irreversible damage is high in JSLE and involves especially the renal, musculoskeletal and neuropsychiatric systems. Although the overall prognosis has markedly improved, thanks to earlier diagnosis and new therapeutic approaches, cardiovascular, hematological events and chronic renal failure remain severe, and constitute the main disease-related causes of death. Treatment is based on hydroxycloroquine and corticosteroids. Immunosuppressive agents must be discussed to decrease the duration of corticosteroids use. New drugs and monoclonal antibodies targeting B-cells and B-cell related cytokines are being evaluated with encouraging results. Management of JSLE has to challenge three objectives: controlling disease progression, obtaining patient's adherence to treatment, and preventing consequences of medication side effects on growth, puberty, development and fertility. Patients' quality of life and psychosocial development have also to be taken into account, as well as the organization of a successful transition from paediatric to adult care.
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PMID:Lupus in adolescence. 1771 96

Spontaneous fractures occur in seemingly normal bone with no apparent blunt-force trauma. Spontaneous fracture occurs primarily in two distinct groups of patients: the very active young and the elderly. Researchers and clinicians have used several terms interchangeably for spontaneous fracture, including pathologic fracture, fragility fracture, compression fracture, or fatigue or insufficiency fracture. Among the most common causes of spontaneous fracture are osteoporosis (calcium deficiency and corticosteroid-induced), malignancy, overexposure to vitamin A, periprosthetic weakening, Brucellosis, cerebral palsy (especially in children), and osteodystrophy because of chronic renal failure. Preliminary research observations indicate that spontaneous fracture may be a rare adverse outcome associated with bisphosphonates.
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PMID:Spontaneous fracture: multiple causes. 1927 52


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