Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Muscle catabolism is a characteristic metabolic response to sepsis, severe infection, and injury. In patients with severe and protracted sepsis, the catabolic response results in muscle wasting and fatigue, which may adversely affect the outcome in these patients. An understanding of the regulation of muscle protein breakdown during sepsis and the mechanisms involved is important from a clinical standpoint and is essential for the development of new therapeutic modalities to prevent protein loss from muscle tissue. Studies in septic patients and experimental animals have provided evidence that the myofibrillar proteins actin and myosin are particularly sensitive to the effects of sepsis. Among the factors that regulate muscle protein breakdown during sepsis, the proinflammatory cytokines tumor necrosis factor and interleukin-1, together with glucocorticoids, are the principal mediators. Intracellular protein breakdown is regulated by multiple proteolytic pathways. Among these, the energy-ubiquitin-dependent pathway accounts for a major portion of muscle protein breakdown during sepsis. The development of specific proteasome inhibitors may make it possible in the future to target the molecular mechanisms of sepsis-induced increase in muscle proteolysis. Such treatment may prove an important avenue to reduce the metabolic cost in patients with severe infection or sepsis.
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PMID:Sepsis: stimulation of energy-dependent protein breakdown resulting in protein loss in skeletal muscle. 945 37

Three methods of internal fixation for MCP arthrodesis of fifteen cadaveric thumbs were used to analyze the biomechanical stability by applying a palmar force, lateral force, and torsion moment. The techniques used included two K-wires 0.045 in parallel (BK), 2 cerclage metallic wires #25 perpendicular to each other (CP), and a 6-holes plate and screws construct from Synthes (PV). The initial rigidity was measured using a Bionix MTS-858. The results after statistical analysis showed: 1) CP was just as rigid as PV for the palmar and lateral tests; 2) CP was, overall, superior to BK in palmar and lateral tests; 3) no difference existed in torsion between the three types of fixation. A comparison was done between the rigidity of the fixation techniques used and the rates of bony nonunion found in the literature. The mean rates of nonunion were reported to be 0-4.0% for the following techniques: CP, tension band wiring (TB), plate and screws, external fixation, compression screw. The rates of nonunion were higher, 7.5-12.5%, for BK, cerclages not perpendicular (CM), bone pegs. According to the results of this biomechanical study and the review of the literature, fixation with BK is the least rigid, and fixation with CP is just as rigid as with PV. The success clinically of CP is yet to be demonstrated. Other studies on the properties of CP for fatigue would be necessary to give a better analysis.
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PMID:[Biomechanical evaluation and clinical correlation of 3 methods of internal fixation of metacarpophalangeal arthrodesis of the thumb]. 984 22

In some patients complaining of chronic fatigue such as those suffering from the chronic fatigue syndrome (CFS), no underlying physical cause can be clearly identified and they typically present a normal thyroid function. Several studies indicate a dysregulation in the type I interferons (IFN-alpha/beta) pathway in CFS resulting in a sustained upregulation of 2('),5(')-oligoadenylate synthetases (2-5OAS). Likewise, patients treated with IFN-alpha/beta usually complain of severe fatigue as a limiting side effect. Beside the 2-5OAS, IFN-alpha/beta induce also the expression of three closely related proteins of unknown function termed the 2-5OAS-like (2-5OASL) proteins. The amino acid sequences of the 2-5OASL proteins display 96% identity with the partial sequence of the thyroid receptor interacting protein (TRIP) 14, further contain two typical thyroid hormone receptor (TR) coregulator domains and feature two ubiquitin C-terminal domains. From these observations, we raise the hypothesis that the 2-5OASL proteins are TRIPs capable of, respectively, repressing TR transactivation and/or signaling the receptor for destruction by the proteasome. Such molecular mechanisms could explain the development of a clinical hypothyroid state in presence of a normal thyroid function.
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PMID:Type I interferons induce proteins susceptible to act as thyroid receptor (TR) corepressors and to signal the TR for destruction by the proteasome: possible etiology for unexplained chronic fatigue. 1260 31

Muscular inactivity leads to atrophy, weakness, and decreased fatigue resistance. In order to provide a window into the dynamic processes that underlie muscle atrophy, we performed global gene expression analysis of rat soleus muscles using Affymetrix GeneChips at 1, 4, 7 and 14 days of hindlimb unloading. Expression of 309 known genes was significantly changed by at least 2-fold (212 upregulated, 97 downregulated). K-means clustering was used to divide these genes into co-regulated clusters based on the similarity of temporal expression patterns. This allowed the development of a timeline of the atrophy process with respect to the behaviour of genes in a broad array of functional categories. Regulatory genes were often upregulated early, in either a transient or sustained manner, but they also populated clusters with later patterns of activation, suggesting different phases of molecular adaptations. Other early events were the activation of ubiquitination genes and downregulation of protein chaperones. In comparison, clusters representing slightly delayed activation patterns included genes involved in fast contraction, glycolysis, translational inhibition, oxidative stress, protein degradation, and amino acid catabolism. Downregulated genes exhibited fewer unique expression patterns and included structural and regulatory genes of the extracellular matrix and cytoskeleton, and genes that define a slow-oxidative phenotype. Other novel findings include the tight co-activation of proteasome subunit and ubiquitination genes, differential regulation of serine proteases and serine protease inhibitors, and the identification of transcriptional, signalling, growth and cell cycle genes that probably play a role in the atrophy process. The present work has uncovered temporal patterns of gene expression that highlight the molecular processes that underlie muscle atrophy and provide new avenues for study.
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PMID:Global analysis of gene expression patterns during disuse atrophy in rat skeletal muscle. 1284 9

(1) First-line treatment of multiple myeloma depends first and foremost on the patient's age. There is no standard treatment for relapses and the median survival time after the first relapse is only 12 to 15 months. (2) Bortezomib, a cytotoxic agent, inhibits the 26S proteasome involved in protein breakdown in mammalian cells. It is licensed for use in myeloma after multiple treatment failure. (3) Three dose-finding studies showed some effects of 1 mg/m2 and 1.3 mg/m2 bortezomib administered twice a week for two weeks, with each course followed by a 10-day treatment-free period. It is not known whether 1.3 mg/m2 is more effective than 1 mg/m2. (4) In a non comparative trial that included 202 patients with multidrug-resistant myeloma, progression-free survival time increased to a median of 6.6 months (compared to 3.3 months after previous relapses), and the median overall survival time was 7 months in the 75% of patients who did not respond and more than 15 months in the 25% of responders. However, given the heterogeneous nature of the study population the evidence from this trial is rather weak. (5) An unblinded comparative trial including 54 patients failed to show whether bortezomib 1.3 mg/m2 was more effective than bortezomib 1 mg/m2 in terms of clinical outcome. Another comparative trial including 669 patients indicated that bortezomib was more effective than dexamethasone in terms of the median time to disease progression (5.7 months versus 3.6 months). (6) Animal studies indicate that bortezomib is cardiotoxic and neurotoxic, and that the interval between the maximal tolerated dose and the fatal dose is very small. Experience with bortezomib use is too limited to know the possible clinical repercussions of these experimental findings. (7) Adverse effects were frequent and varied in clinical trials. They included fatigue, nausea and vomiting, diarrhea, anemia, thrombocytopenia and peripheral neuropathies. They affected 30% to 60% of patients overall, and were severe in about 10% to 20% of patients. Other adverse effects included hypotension, fever, headache, pain and dehydration. (8) Bortezomib is metabolised by cytochrome P 450 isoenzyme 3A4, and this implies a high risk of drug-drug interactions. (9) Each vial of bortezomib contains more of the drug than is needed for one injection. This is not only wasteful, but also carries a risk of overdosing, with potentially serious consequences, should the entire contents be injected by mistake. (10) Bortezomib may be used as a last resort in some patients with multiple myeloma, but the individual risk-benefit balance must be carefully weighed in each case.
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PMID:Bortezomib: new drug. A last resort in myeloma: modest efficacy, major risks. 1598 89

Muscle wasting in sepsis is a significant clinical problem because it results in muscle weakness and fatigue that may delay ambulation and increase the risk for thromboembolic and pulmonary complications. Treatments aimed at preventing or reducing muscle wasting in sepsis, therefore, may have important clinical implications. Recent studies suggest that sepsis-induced muscle proteolysis may be initiated by calpain-dependent release of myofilaments from the sarcomere, followed by ubiquitination and degradation of the myofilaments by the 26S proteasome. In the present experiments, treatment of rats with one of the calpain inhibitors calpeptin or BN82270 inhibited protein breakdown in muscles from rats made septic by cecal ligation and puncture. The inhibition of protein breakdown was not accompanied by reduced expression of the ubiquitin ligases atrogin-1/MAFbx and MuRF1, suggesting that the ubiquitin-proteasome system is regulated independent of the calpain system in septic muscle. When incubated muscles were treated in vitro with calpain inhibitor, protein breakdown rates and calpain activity were reduced, consistent with a direct effect in skeletal muscle. Additional experiments suggested that the effects of BN82270 on muscle protein breakdown may, in part, reflect inhibited cathepsin L activity, in addition to inhibited calpain activity. When cultured myoblasts were transfected with a plasmid expressing the endogenous calpain inhibitor calpastatin, the increased protein breakdown rates in dexamethasone-treated myoblasts were reduced, supporting a role of calpain activity in atrophying muscle. The present results suggest that treatment with calpain inhibitors may prevent sepsis-induced muscle wasting.
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PMID:Treatment of rats with calpain inhibitors prevents sepsis-induced muscle proteolysis independent of atrogin-1/MAFbx and MuRF1 expression. 1645 66

Neurodegenerative diseases can have long preclinical phases and insidious progression patterns, but the mechanisms of disease progression are poorly understood. Because quantitative accounts of neuronal circuitry affected by disease have been lacking, it has remained unclear whether disease progression reflects processes of stochastic loss or temporally defined selective vulnerabilities of distinct synapses or axons. Here we derive a quantitative topographic map of muscle innervation in the hindlimb. We show that in two mouse models of motoneuron disease (G93A SOD1 and G85R SOD1), axons of fast-fatiguable motoneurons are affected synchronously, long before symptoms appear. Fast-fatigue-resistant motoneuron axons are affected at symptom-onset, whereas axons of slow motoneurons are resistant. Axonal vulnerability leads to synaptic vesicle stalling and accumulation of BC12a1-a, an anti-apoptotic protein. It is alleviated by ciliary neurotrophic factor and triggers proteasome-dependent pruning of peripheral axon branches. Thus, motoneuron disease involves predictable, selective vulnerability patterns by physiological subtypes of axons, episodes of abrupt pruning in the target region and compensation by resistant axons.
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PMID:Selective vulnerability and pruning of phasic motoneuron axons in motoneuron disease alleviated by CNTF. 1647 88

(1) When multiple myeloma relapses more than one year after initial treatment, the median survival time is only 12 to 15 months. (2) Bortezomib is a cytotoxic agent that inhibits the 26S proteasome, a complex involved in intracellular protein breakdown in mammals. Bortezomib was initially licensed for the treatment of myeloma after multiple treatment failure; its indications were subsequently modified to include second-line treatment. (3) Second-line bortezomib therapy has not been compared with haematopoietic stem cell grafting, a treatment with documented efficacy. (4) An unblinded comparative trial involving 54 patients requiring second-line treatment showed that bortezomib at a dose of 1.3 mg/m to the 2nd power (twice a week for two weeks, followed by a 10 day rest period) was significantly more effective than a dose of 1 mg/m to the 2nd power in terms of the median survival time (not determined in the 1.3 mg group, versus 26.7 months in the 1 mg group) and the median time to disease progression (11.7 versus 4.2 months). (5) Among 251 patients in whom first-line treatment had failed, bortezomib was significantly more effective than dexamethasone: the one-year survival rate was 80% versus 66% on dexamethasone, and the progression-free survival time was 6.2 months versus 3.5 months. (6) Adverse effects occurred in 30% to 60% of patients enrolled in clinical trials, and were severe in about 10% to 20% of patients. They mainly included fatigue, nausea and vomiting, diarrhoea, anaemia, thrombocytopenia, and peripheral neuropathy. Animal studies indicated a possible risk of cardiotoxicity, and cases of cardiac arrhythmias and conduction disorders were observed in clinical trials. (7) Bortezomib is metabolised by the cytochrome P450 isoenzyme CYP3A4, with a high risk of interactions. (8) The vials contain an excessive amount of this costly drug, creating a risk of inadvertent overdose and leading to unnecessary waste. (9) In practice, bortezomib is an alternative to steroid therapy for patients with multiple myeloma in whom first-line treatment has failed and who do not qualify for stem cell grafting. The choice of treatment must be discussed with the patient, after providing thorough information on the likely benefits and risks
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PMID:Bortezomib: new indication. Second-line treatment of myeloma: limited efficacy, major risks. 1676 98

Inspiratory muscle weakness in patients with chronic obstructive pulmonary disease (COPD) is of major clinical relevance; maximum inspiratory pressure generation is an independent determinant of survival in severe COPD. Traditionally, inspiratory muscle weakness has been ascribed to hyperinflation-induced diaphragm shortening. However, more recently, invasive evaluation of diaphragm contractile function, structure, and biochemistry demonstrated that cellular and molecular alterations occur, of which several can be considered of pathologic nature. Although the fiber-type shift toward oxidative type I fibers in COPD diaphragm is regarded as beneficial, rendering the overloaded diaphragm more resistant to fatigue, the reduction of diaphragm fiber force generation in vitro likely contributes to diaphragm weakness. The reduced diaphragm force generation at single-fiber level is associated with loss of myosin content. Moreover, the diaphragm in COPD is exposed to oxidative stress and sarcomeric injury. The current Pulmonary Perspective postulates that the oxidative stress and sarcomeric injury activate proteolytic machinery, leading to contractile protein wasting and, consequently, loss of force-generating capacity of diaphragm fibers in patients with COPD. Interestingly, several of these presumed pathologic alterations are already present early in the course of the disease (GOLD I/II), although these patients do not appear to be limited in their daily-life activities. Therefore, investigating in vivo diaphragm function in mild to moderate COPD should be the focus of future research. Treatment of diaphragm dysfunction in COPD is complex because its etiology is unclear, but recent findings show promise for the use of proteasome inhibitors in syndromes associated with muscle wasting, such as the diaphragm in COPD.
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PMID:Diaphragm muscle fiber dysfunction in chronic obstructive pulmonary disease: toward a pathophysiological concept. 1741 28

Skeletal muscle is composed of heterogeneous myofibers with distinctive rates of contraction, metabolic properties, and susceptibility to fatigue. We show that class II histone deacetylase (HDAC) proteins, which function as transcriptional repressors of the myocyte enhancer factor 2 (MEF2) transcription factor, fail to accumulate in the soleus, a slow muscle, compared with fast muscles (e.g., white vastus lateralis). Accordingly, pharmacological blockade of proteasome function specifically increases expression of class II HDAC proteins in the soleus in vivo. Using gain- and loss-of-function approaches in mice, we discovered that class II HDAC proteins suppress the formation of slow twitch, oxidative myofibers through the repression of MEF2 activity. Conversely, expression of a hyperactive form of MEF2 in skeletal muscle of transgenic mice promotes the formation of slow fibers and enhances running endurance, enabling mice to run almost twice the distance of WT littermates. Thus, the selective degradation of class II HDACs in slow skeletal muscle provides a mechanism for enhancing physical performance and resistance to fatigue by augmenting the transcriptional activity of MEF2. These findings provide what we believe are new insights into the molecular basis of skeletal muscle function and have important implications for possible therapeutic interventions into muscular diseases.
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PMID:Histone deacetylase degradation and MEF2 activation promote the formation of slow-twitch myofibers. 1778 35


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