Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 27-yr-old woman with lifelong severe exercise intolerance manifested by muscle fatigue, lactic acidosis, and prominent symptoms of dyspnea and tachycardia induced by trivial exercise was found to have a skeletal muscle respiratory chain defect characterized by low levels of reducible cytochromes a + a3 and b in muscle mitochondria and marked deficiency of cytochrome c oxidase (complex IV) as assessed biochemically and immunologically. Investigation of the pathophysiology of the exercise response in the patient revealed low maximal oxygen uptake (1/3 that of normal sedentary women) in cycle exercise and impaired muscle oxygen extraction as indicated by profoundly low maximal systemic arteriovenous oxygen difference (5.8 ml/dl; controls = 15.4 +/- 1.4, mean +/- SD). The increases in cardiac output and ventilation during exercise, normally closely coupled to muscle metabolic rate, were markedly exaggerated (more than two- to threefold normal) relative to oxygen uptake and carbon dioxide production accounting for prominent tachycardia and dyspnea at low workloads. Symptoms in our patient are similar to those reported in other human skeletal muscle respiratory chain defects involving complexes I and III, and the exaggerated circulatory response resembles that seen during experimental inhibition of the mitochondrial respiratory chain. These results suggest that impaired oxidative phosphorylation in working muscle disrupts the normal regulation of cardiac output and ventilation relative to muscle metabolic rate in exercise.
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PMID:Exercise intolerance, lactic acidosis, and abnormal cardiopulmonary regulation in exercise associated with adult skeletal muscle cytochrome c oxidase deficiency. 254 23

The pathophysiology, clinical features, and management of cyanide toxicity are reviewed and sources of cyanide are listed. Cyanide is a deadly poison that is found in many foods and household and industrial products, including some that are readily available. Cyanide binds with cytochrome oxidase, the enzyme responsible for oxidative phosphorylation, and paralyzes cellular respiration. Because the tissues cannot use oxygen that is delivered, aerobic metabolism ceases. The signs and symptoms of cyanide poisoning reflect the extent of cellular hypoxia. Manifestations may include respiratory abnormalities (progressing from tachypnea and dyspnea to respiratory depression and apnea), hemodynamic instability, metabolic acidosis, and, possibly, local irritant effects after oral ingestion of cyanide. The mainstays of therapy are 100% oxygen and specific antidotes to cyanide. Sequential treatment with amyl nitrite by inhalation, intravenous sodium nitrite 3%, and intravenous sodium thiosulfate 25% is directed toward decreasing the amount of cyanide available for cellular binding. Nitrites convert hemoglobin to methemoglobin, which reacts with cyanide to form cyanomethemoglobin. Sodium thiosulfate serves as a source of sulfur groups, which are needed for conversion of cyanide to thiocyanate, a compound that is relatively less toxic and is excreted renally. Supportive care also is important. Cobalt EDTA, hydroxocobalamin, and aminophenols have also been used but are not considered standard treatments. Cyanide poisoning is a medical emergency that requires prompt recognition and immediate and aggressive treatment.
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PMID:Clinical features and management of cyanide poisoning. 353 Jun 15

Although linked with cardiac dysfunction, the association of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) and pulmonary artery hypertension (PAH) has not been previously described. PAH and right ventricular heart failure were identified by echocardiography in a 3-year-old boy with a history of hypotonia, microcephaly and developmental delay. He initially presented with a 10-day history of dyspnoea, dependent oedema and reduced oral intake. Lactic acidosis was noted on serial arterial blood sampling and cerebrospinal fluid. Muscle biopsy demonstrated cytochrome-c oxidase-positive 'ragged-red' fibres consistent with MELAS; subsequent analyses revealed the m.3243A>G point mutation most commonly associated with MELAS. The mutation was heteroplasmic, representing 92% of the total mtDNA from a lung sample. Nitric oxide and epoprostenol were administered without significant clinical or echocardiographic improvement of his PAH. A 'mitochondrial cocktail' including biotin, riboflavin, carnitine and coenzyme Q10 also was provided. Five months after presentation, he developed seizures; MRI imaging of his brain demonstrated multiple focal lesions. His clinical status worsened with increasing cardiopulmonary failure. He died two months later. Although therapy for both MELAS and PAH remains limited, recent investigations suggest a beneficial role for l-arginine in both conditions, implying a possible common pathophysiology. Mitochondrial diseases such as MELAS should be considered in cases of idiopathic PAH, particularly when associated with multisystem involvement including short stature, hearing loss, renal dysfunction, retinopathy, diabetes mellitus, migraines, seizures, ophthalmoplegia, fatigability and weakness.
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PMID:Pulmonary artery hypertension in a child with MELAS due to a point mutation of the mitochondrial tRNA((Leu)) gene (m.3243A>G). 1818 Oct 29

Cyanide poisoning can present in multiple ways, given its widespread industrial use, presence in combustion products, multiple physical forms, and chemical structures. The primary target of toxicity is mitochondrial cytochrome oxidase. The onset and severity of poisoning depend on the route, dose, physicochemical structure and other variables. Common poisoning features include dyspnea, altered respiratory patterns, abnormal vital signs, altered mental status, seizures, and lactic acidosis. Our present knowledge supports cyanide poisoning treatment based on excellent supportive care with adjunctive antidotal therapy. Multiple antidotes exist and vary in regional availability. All currently marketed antidotes appear to be effective. Antidotal mechanisms include chelation, formation of stable, less toxic complexes, methemoglobin induction, and sulfane sulfur supplementation for detoxification by endogenous rhodanese. Each antidote has advantages and disadvantages. For example, hydroxocobalamin is safer than the methemoglobin inducers in patients with smoke inhalation. Research for new, safer and more effective cyanide antidotes continues.
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PMID:Antidotes for acute cyanide poisoning. 2235 28

A new cystic echinococcosis case in a cat in Uruguay is reported herein. The cat was taken to a veterinary clinic in Rocha city, Uruguay, due to dyspnea, constipation and abdominal enlargement. During surgery a large quantity of cysts was retrieved from the abdominal cavity. The cysts were morphologically studied and confirmed as Echinococcus granulosus sensu stricto (genotype 1) by molecular tools using cytochrome oxidase submit 1 and small subunit ribosomal RNA gene as target genes. Moreover, for the first time a coinfection with feline immunodeficiency virus (FIV) was detected. FIV-induced immunosuppression could be a determining factor in the development of cystic echinococcosis in cats.
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PMID:First case of peritoneal cystic echinococcosis in a domestic cat caused by Echinococcus granulosus sensu stricto (genotype 1) associated to feline immunodeficiency virus infection. 2429 Dec 89