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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypometabolic state following hypothermia is known to protect tissues from ischemic injury. Hypothyroidism produces a hypometabolic state. The present study was undertaken to investigate the protective effects of hypothyroidism following cerebral ischemia and to ascertain the underlying mechanism. Euthyroid (E) and hypothyroid (H) animals were exposed to a 2 h of middle cerebral artery occlusion followed by 24 h of reperfusion (I/R). Specific enzymatic methods and flowcytometry were used to assess the quantitative changes of molecules involved in neuronal damage as well as in protection. As compared to euthyroid ischemic reperfused (E + I/R) rats, H + I/R rats had insignificant neurological deficit, and smaller area of infarct. H + I/R rats had significantly lower markers of oxidative stress, and lactate dehydrogenase (LDH) activity (a marker for necrosis). Natural antioxidant activity (particularly superoxide dismutase) and integrity of mitochondria (membrane potential) were maintained in H + I/R group but not in E + I/R group. The number of neurons undergoing apoptosis significantly lower in hypothyroid ischemic rats as compared to euthyroid ones. These results suggest that hypothyroid animals face ischemia and reperfusion much better compared to euthyroid animals. A possible explanation could be the decreased oxidative stress and maintained antioxidant activity that finally leads to a decrease in necrosis and apoptosis. These observations may suggest strategies to induce brain-specific downregulation of metabolism that may have implications in the management of strokes in human beings.
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PMID:Reduction in oxidative stress and cell death explains hypothyroidism induced neuroprotection subsequent to ischemia/reperfusion insult. 1661 21

Cardiolipin (CL) is a structurally unique dimeric phospholipid localized in the inner mitochondrial membrane where it is required for optimal mitochondrial function. In addition to its role in maintaining membrane potential and architecture, CL is known to provide essential structural and functional support to several proteins involved in mitochondrial bioenergetics. A loss of CL content, alterations in its acyl chain composition, and/or CL peroxidation have been associated with mitochondrial dysfunction in multiple tissues in a variety of pathological conditions, including ischemia, hypothyroidism, aging, and heart failure. Recently, aberrations in CL metabolism have been implicated as a primary causative factor in the cardioskeletal myopathy known as Barth syndrome, underscoring an important role of CL in human health and disease. The purpose of this review is to provide an overview of evidence that has linked changes in the CL profile to mitochondrial dysfunction in various pathological conditions. In addition, a brief overview of CL function and biosynthesis, and a discussion of methods used to examine CL in biological tissues are provided.
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PMID:Role of cardiolipin alterations in mitochondrial dysfunction and disease. 1689 48

Impaired microcirculation with evolving sludge phenomenon and thrombosis underlie placental changes in maternal thyroid disease. Capillary blood circulatory defect is largely due to villous immaturity. Placental tissue ischemia gives rise to fibrinoid, sclerosis, and alternative processes. Dysadaptive changes are mostly observed in thyrotoxicosis and hypothyroidism. Adaptive processes evolving at the ultrastructural level are best pronounced in euthyroid goiter.
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PMID:[Impact of maternal thyroid disease on the formation of relationships in the maternal-placental-fetal system]. 1698 91

Peripheral arterial disease (PAD) in the elderly can be: 1) asymptomatic, 2) associated with intermittent claudication, or 3) cause critical limb ischemia. Persons with PAD are at increased risk for all-cause mortality, cardiovascular mortality, and mortality from coronary artery disease (CAD). Hypertension, diabetes mellitus, dyslipidemia, and hypothyroidism should be treated, and smoking should be stopped. Statins reduce the incidence of intermittent claudication and increase exercise duration until the onset of intermittent claudication in persons with PAD and hypercholesterolemia. Antiplatelet drugs (eg, aspirin, clopidogrel, angiotensin-converting enzyme [ACE] inhibitors, statins) should be given to all persons with PAD. Beta blockers should be given if CAD is present. Exercise rehabilitation programs and cilostazol lengthen exercise time until leg pain develops. Chelation therapy has no scientific basis and should be avoided. Revascularization or amputation may be indicated in some cases.
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PMID:Peripheral arterial disease. 1722 18

Massive Ca(2+) accumulation in mitochondria, plus the stimulating effect of an inducing agent, i.e., oxidative stress, induces the so-called permeability transition, which is characterized by the opening of a nonspecific pore. This work was aimed at studying the influence of thyroid hormone on the opening of such a nonspecific pore in kidney mitochondria, as induced by an oxidative stress. To meet this objective, membrane permeability transition was examined in mitochondria isolated from kidney of euthyroid and hypothyroid rats, after a period of ischemia/reperfusion. It was found that mitochondria from hypothyroid rats were able to retain accumulated Ca(2+) to sustain a transmembrane potential after Ca(2+) addition, as well as to maintain matrix NAD(+) and membrane cytochrome c content. The protective effect of hypothyroidism was clearly opposed to that occurring in ischemic reperfused mitochondria from euthyroid rats. Our findings demonstrate that these mitochondria were unable to preserve selective membrane permeability, except when cyclosporin A was added. It is proposed that the protection is conferred by the low content of cardiolipin found in the inner membrane. This phospholipid is required to switch adenine nucleotide translocase from specific carrier to a non-specific pore.
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PMID:Hypothyroidism provides resistance to kidney mitochondria against the injury induced by renal ischemia-reperfusion. 1730 78

Patients with hypothyroidism have an increased risk of coronary artery disease because of significant changes in lipid metabolism and arterial hypertension. We report a 67-year-old man who developed acute myocardial infarction following hormone replacement in hypothyroidism in spite of no previous cardiac symptoms and no ischemia in intravenous dipyridamole myocardial perfusion imaging. Careful examination for ischemic heart disease should be performed before hormone replacement in hypothyroidism.
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PMID:Acute myocardial infarction following hormone replacement in hypothyroidism. 1737 84

Thyroid hormones have many effects on the heart and vascular system. Although cardiac output is reduced in hypothyroidism, heart failure is relatively rare because there is a lower demand for peripheral oxygen delivery. Hypothyroidism may also result in accelerated atherosclerosis and coronary artery disease. We report the case of a 55-year-old man with severe heart failure associated with severe longstanding untreated hypothyroidism. The patient was admitted for shortness of breath and chest pain. On presentation, signs and symptoms of severe hypothyroidism and heart failure were noticed. The electrocardiogram showed sinus bradycardia and ischemia. Thyroid stimulating hormone was extremely elevated and thyroid hormone levels were undetectable. A cardiac ultrasonography exam revealed abnormalities of the left ventricular dimensions and function consistent with dilated cardiomyopathy. Coronary angiography showed severe multivessel disease. Coronary by-pass was deemed necessary, but surgery was postponed because of severe heart failure. After an increasingly downhill clinical course, the patient died, eight month after his initial presentation, owing to severe heart failure. This patient represents an example of an overlooked diagnosis of severe hypothyroidism, rarely encountered nowadays, leading to dramatic consequences.
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PMID:Heart failure and dilated cardiomyopathy associated with severe longstanding untreated hypothyroidism. 1796 46

Fenofibrate, a fibric acid derivative, is used to treat diabetic dyslipidemia, hypertriglyceridemia, and combined hyperlipidemia alone or in combination with statins. Rhabdomyolysis is defined as a pathological condition of skeletal muscle cell damage leading to the release of toxic intracellular material into the circulation. Its major causes include trauma, ischemia, toxins, metabolic disorders, infections, and drugs. Rhabdomyolysis associated with fenofibrate is extremely rare. In nearly all of the presented cases, there was a predisposing factor for rhabdomyolysis such as diabetes, older age, renal insufficiency, and hypothyroidism. Here, we report a nondiabetic, nonhypothyroidic young female patient without any known prior renal disease presenting with acute renal failure developing after fenofibrate treatment.
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PMID:Acute renal failure secondary to fenofibrate monotherapy-induced rhabdomyolysis. 1799 63

Smoking should be stopped and hypertension, diabetes mellitus, dyslipidemia, and hypothyroidism treated in patients with peripheral arterial disease (PAD) of the lower extremities. Statins decrease the incidence of intermittent claudication and improve exercise duration until the onset of intermittent claudication in persons with PAD and hypercholesterolemia. Antiplatelet drugs such as aspirin or clopidogrel, especially clopidogrel, angiotensin-converting enzyme inhibitors, and statins should be given to all persons with PAD. Beta blockers should be given if coronary artery disease is present. Exercise rehabilitation programs and cilostazol increase exercise time until intermittent claudication develops. Chelation therapy should be avoided. Indications for lower extremity percutaneous transluminal angioplasty or bypass surgery are (1) incapacitating claudication in persons interfering with work or lifestyle, (2) limb salvage in persons with limb-threatening ischemia as manifested by rest pain, nonhealing ulcers, and/or infection or gangrene, and (3) vasculogenic impotence.
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PMID:Management of peripheral arterial disease of the lower extremities. 1802 17

There is accumulating evidence showing that ischemic preconditioning (PC) may lose its cardioprotective effect in the diseased states. The present study investigated whether PC can be effective in hypothyroidism, a clinical condition which is common and often accompanies cardiac diseases such as heart failure and myocardial infarction. Hypothyroidism was induced in rats by 3-week administration of 6n-propyl-2-thiouracil in water (0.05 %). Normal and hypothyroid hearts (HYPO) were perfused in Langendorff mode and subjected to 20 min of zero-flow global ischemia and 45 min of reperfusion. A preconditioning protocol (PC) was also applied prior to ischemia. HYPO hearts had significantly improved post-ischemic recovery of left ventricular developed pressure, end-diastolic pressure and reduced lactate dehydrogenase release. Furthermore, phospho-JNK and p38 MAPK levels after ischemia and reperfusion were 4.0 and 3.0 fold lower in HYPO as compared to normal hearts (P<0.05). A different response to PC was observed in normal than in HYPO hearts. PC improved the post-ischemic recovery of function and reduced the extent of injury in normal hearts but had no additional effect on the hypothyroid hearts. This response, in the preconditioned normal hearts, resulted in 2.5 and 1.8 fold smaller expression of the phospho-JNK and phospho-p38 MAPK levels at the end of reperfusion, as compared to non-PC hearts (P<0.05), while in HYPO hearts, no additional reduction in the phosphorylation of these kinases was observed after PC. Hypothyroid hearts appear to be tolerant to ischemia-reperfusion injury. This response may be, at least in part, due to the down-regulation of ischemia-reperfusion induced activation of JNKs and p38 MAPK kinases. PC is not associated with further reduction in the activation of these kinases in the hypothyroid hearts and fails to confer added protection in those hearts.
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PMID:Ischemic preconditioning fails to confer additional protection against ischemia-reperfusion injury in the hypothyroid rat heart. 1819 89


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