Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synthetic parathyroid hormone (PTH), particularly the molecular fragment containing amino acids one to 34 (1-34), has been shown to produce coronary vasodilation and systemic vasodilation without tachycardia. On this basis, we tested the hypothesis that PTH(1-34) would favorably affect oxygen balance in acutely ischemic myocardium and reduce the extent of injury after coronary occlusion. Experiments were done upon the left anterior descending coronary artery which was ligated through a thoracotomy in anesthetized dogs subjected to ligation of the left anterior descending coronary artery. After 30 minutes of ischemia, the dogs were randomly assigned to either a group which received an intracoronary infusion of 0.008 nanomoles per kilogram of body weight per minute of PTH (1-34) for ten minutes at intervals of 30 minutes or a control group which received intracoronary saline solution. PTH(1-34) increased circumflex artery blood flow 290 +/- 62 per cent (p less than 0.005) and coronary venous return from the ischemic area 190 +/- 12 per cent (p less than 0.005) while reducing mean arterial pressure 12.5 +/- 1.7 per cent (p less than 0.05) without a change in the heart rate. These hemodynamic changes resulted in a 54.3 +/- 3.7 per cent (p less than 0.005) decrease in ischemic myocardial oxygen extraction and a reduction of infarct size (25 +/- 5 per cent of myocardium at risk in treated versus 75 +/- 10 per cent in the control group). It is concluded that PTH given after coronary artery occlusion increases collateral blood flow and oxygen supply to the ischemic myocardium while reducing oxygen requirements. Thus, PTH may offer significant protection for the acutely ischemic myocardium.
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PMID:Parathyroid hormone reduces acute ischemic injury of the myocardium. 378 26

Post-transplant cure tubular necrosis (ATN) represents the most frequent cause of delayed graft function in the immediate post-transplant period. Several causes have been associated with the development of post-transplant ATN such as donor and recipient ages, cold-warm ischemia times, HLA mismatches, and postoperative hypotension. In the present study, we retrospectively evaluated the role of secondary hyperparathyroidism and high parathyroid hormone (PTHi) blood levels in the development of post-transplant ATN. One hundred patients submitted to cadaveric renal transplant between January 1992 and March 1993 in our unit were included. Twenty-seven patients (27%) developed post-transplant ATN and seventy-three (73%) did not. Post-transplant ATN was significantly associated with gender (p < 0.01), recipient age (p < 0.01), number of transplantations (p < 0.01), time on hemodialysis (p < 0.001), cold ischemic time (p < 0.05) and PTHi levels (p < 0.001). The bivariate and multivariate statistical analyses demonstrated that the development of post-transplant ATN was significantly more frequent in females; retransplanted patients, patients with a time on dialysis of more than 5 years, recipients over 60 years old, patients with a PTHi blood level higher than 240 pg/ml (4 times normal level) and a cold ischemia time of more than 18 h. Based on these results, we conclude that high PTHi blood levels in the renal transplant recipients represent a relevant factor in the development of post-transplant ATN. The administration of intravenous pulsed of 1,25(OH)2D3 and/or a calcium channel blocker in the perioperative period could be useful to decrease the incidence and severity of post-transplant ATN in these patients.
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PMID:Role of secondary hyperparathyroidism in the development of post-transplant acute tubular necrosis. 874 60

Calciphylaxis is a rare and life-threatening complication that is estimated to occur in 1% of patients with ESRD each year. Typically, extensive microvascular calcification and occlusion/thrombosis leads to violaceous skin lesions, which progress to nonhealing ulcers and sepsis. Secondary infection of skin lesions is common, often leading to sepsis and death. The lower extremities are predominantly involved (roughly 90% of patients). Patients with skin involvement over the trunk or proximal extremities have a poorer prognosis. Although most calciphylaxis patients have abnormalities of the calcium:phosphate axis or elevated levels of parathyroid hormone, these abnormalities do not appear to be fundamental to the pathophysiology of the disorder, and the etiology of calciphylaxis remains unclear. Recently, functional protein C deficiency has been hypothesized to cause a hypercoagulable state that could induce thrombosis in small vessels, with resulting skin ischemia, necrosis, and gangrene. The lack of understanding of the pathophysiology of the disease results in treatments that are equally unsatisfactory. Patients who undergo parathyroidectomy have a tendency to improve, but the prognosis for the disease is poor and mortality remains high.
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PMID:Calciphylaxis in chronic renal failure. 882 11

Thiazide diuretic drugs act in the distal convoluted tubule (DCT) to inhibit a Na+Cl- cotransporter and enhance reabsorption of luminal calcium. The density of receptors for thiazides in the rat DCT is known to be increased by adrenocortical steroids, furosemide, and bendroflumethiazide, but decreased by ischemia. Because the DCT is a physiologic site of action by calcitonin and parathyroid hormone, this study examined the effects of these calcitropic hormones in thyroparathyroidectomized Sprague-Dawley rats on (1) the density of the rat thiazide receptor (TZR), as quantitated by binding of (3H)metolazone to renal membranes, and (2) urinary electrolyte excretion rate. Salmon calcitonin (sCT) (20 to 100 ng/h) (1) increased the density of the renal TZR twofold, an effect that is maximal by 6 h after sCT administration, and (2) decreased urinary calcium excretion rate. Adequate dietary calcium must be provided for the effects of sCT to be observed. Regression analysis demonstrated that renal TZR density correlated negatively with total urinary calcium excretion rate but not with plasma calcium ion concentration. In addition, neither rat calcitonin (rCT), at doses that cause hypocalcemia, nor parathyroid hormone, at doses that cause hypercalcemia, produce direct effects on TZR density in the DCT of the thyroparathyroidectomized rat. Our findings indicate that upregulation of TZR by sCT, which occurs independently of plasma calcium-ion concentration, is likely via a calcitonin-like receptor other than that for rat calcitonin itself.
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PMID:Effects of calcium-modulating hormones on thiazide receptor density. 882 21

The mammalian kidney is susceptible to injury by ischemia/reperfusion and toxins, and regeneration after injury is characterized by hyperplasia and recovery of the damaged epithelial cells that line the tubules. Locally produced growth factors may serve as mediators of nephrogenesis and differentiation during renal development and of renal regeneration after acute injury. In cultured cells, administration of one or a mixture of growth factors to quiescent cells will initiate progression through the cell cycle and cell division. In the adult kidney, cell division normally is very low, but will increase up to 10-fold after acute injury. In addition to proliferation after lethal injury, there also is cellular repair in cells that have undergone sublethal injury. Recent studies indicate that growth factors inhibit programmed cell death in response to acute injury. Growth factors also may initiate or promote protein and lipid biosynthesis and provide an intracellular milieu that promotes cellular repair. In addition to cellular repair, growth factors also may be involved in the re-establishment of cell-extracellular matrix and cell-cell integrity. Finally, growth factors may limit injury by decreasing the factors that induce damage. Increased local renal expression of growth factors in response to acute injury include heparin binding epidermal growth factor (HB-EGF), hepatocyte growth factor (HGF), insulin-like growth factor-I (IGF-I), transforming growth factor-beta, parathyroid hormone-related peptide, and acidic fibroblast growth factor. In a number of experimental models of acute renal injury, administration of exogenous growth factors has been shown to accelerate both structural and functional recovery. Specifically, EGF, IGF-1, and HGF all have been shown to be effective in this regard. These studies are reviewed and potential therapeutic uses of growth factors and cytokines will be discussed.
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PMID:Growth factors and cytokines in acute renal failure. 911 40

In chronic uremia, apart from frequent coronary lesions, further abnormalities of the heart recently reported include (1) left ventricular hypertrophy, not completely explained by hypertension, (2) interstitial myocardial fibrosis, for which parathyroid hormone is a permissive factor, (3) reduced myocardial perfusion reserve, secondary to functional and structural changes of intramyocardial arteries and to reduced capillary density, (4) abnormalities of myocardial metabolism, which act in concert with restriction of blood flow by microvascular abnormalities to reduce ischemic tolerance. Such metabolic abnormalities include diminished responsiveness to beta-adrenergic stimulation, abnormal control of intracellular calcium concentration, impaired maintenance of energy-rich nucleotide concentrations under conditions of ischemia, impaired insulin-mediated glucose uptake, and abnormalities of myocardial oxidative metabolism.
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PMID:Cardiac disease in chronic uremia: pathophysiology. 923 26

Calciphylaxis is a severe complication of chronic renal failure, confined almost exclusively to patients on dialysis therapy. Histological characteristics of calciphylaxis include small-vessel calcifications of skin, subcutaneous tissue, and visceral organs. These vascular changes promote tissue ischemia that often results in tissue necrosis. In this study, we investigated the extent of skin ischemia in patients with calciphylaxis by means of transcutaneous oxygen tension (TCPO(2)) measurement, a noninvasive test that accurately assesses skin oxygenation. TCPO(2) levels were measured in 21 patients with calciphylaxis and 21 age- and sex-matched patients without evidence of calciphylaxis (controls). TCPO(2) levels were measured bilaterally at the chest, anterior abdomen, and upper thigh while patients breathed room air and after a 30-minute exposure to 100% fraction of inspired oxygen (FIO(2)). Compared with controls, patients with calciphylaxis showed significantly lower TCPO(2) levels at each body region. In both controls and patients with calciphylaxis, lower TCPO(2) levels correlated with increased weight and use of hemodialysis. No correlation with serum parathyroid hormone (PTH), serum calcium, or serum phosphorus values was present, although 39% of the patients with calciphylaxis had markedly elevated PTH values (sixfold greater than normal; >300 pg/dL). Low TCPO(2) levels in patients with calciphylaxis were documented in body regions with and without skin lesions. In patients with calciphylaxis, extremely low TCPO(2) values (</=30 mm Hg while patients breathed room air) were present in 62% of the body regions with skin lesions and 26% of the body regions without lesions. Room-air TCPO(2) levels </=30 mm Hg were present in only 0.8% of the body regions of control patients. TCPO(2) levels obtained while patients breathed 100% FIO(2) remained lower in patients with calciphylaxis than in controls. In conclusion, TCPO(2) levels are abnormally low in patients with calciphylaxis, indicating that severe and diffuse skin ischemia exists, even at areas free of skin lesions. Low TCPO(2) values did not substantially increase with 100% FIO(2) in many patients with calciphylaxis, suggesting a fixed insufficiency of the skin vessels. This study shows that TCPO(2) measurements may allow rapid and noninvasive screening for skin ischemia before the development of skin lesions in patients with calciphylaxis.
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PMID:Transcutaneous oxygen tension in patients with calciphylaxis. 1127 80

The effect of synthetic parathyroid hormone (PTH)-related peptide [PTHrP(1-34)] on regional myocardial function was studied in 11 anesthetized pigs. Intracoronary infusion of PTHrP (cumulative dose: 14 +/- 1 microg) decreased coronary resistance to 33 +/- 2% of baseline (P < 0.05) and regional myocardial function to 90 +/- 3% of baseline (not significant). Ischemia-reperfusion alters the activity of several kinases and therefore possibly the myocardial effects of PTHrP. In stunned myocardium, induced by 20-min ischemia and 30-min reperfusion, the dose of PTHrP reducing coronary resistance to a minimum of 29 +/- 2% was decreased to 8 +/- 2 microg (P < 0.05). Regional myocardial function was no longer decreased but increased to 132 +/- 9% (P < 0.05). The increase in regional myocardial function during PTHrP was inversely related to baseline function at 30-min reperfusion in vivo (r = 0.9) as well as in myocytes isolated from stunned pig hearts (r = 0.7). In isolated rat hearts subjected to 30-min global ischemia followed by 30-min reperfusion, blockade of endogenous PTHrP by d-Trp(12)-Tyr(34)-PTH(7-34) attenuated the recovery of left ventricular developed pressure by 30 +/- 14% (P < 0.05). Thus endogenous and exogenous PTHrP impact on the function of stunned myocardium.
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PMID:Parathyroid hormone-related peptide improves contractile function of stunned myocardium in rats and pigs. 1248 16

The parathyroid hormone-related peptide (PTHrP) was initially identified in the early eighties, as the humoral mediator causing hypercalcaemia associated with malignancy. However, recently PTHrP was also shown to mediate a wide range of local paracrine/autocrine and intracrine functions in various tissues under physiological and pathological conditions. Indeed, PTHrP is a polyhormone, which can act through different receptors, including the type 1 parathyroid hormone (PTH) receptor 1 (PTH-1R). In the cardiovascular system, PTHrP appears to have potent effects on vascular smooth muscle cells and cardiomyocytes, where it participates in different pathological conditions, such as ischemia and heart failure. Therefore, it is conceivable that further studies on the regulation of PTHrP expression, characterization of its autocrine/paracrine/intracrine functions and definition of its intracellular signal transduction pathways in cardiomyocytes and cardiac vascular smooth muscle cells can elucidate the potential role of PTHrP in cardiovascular pathophysiology.
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PMID:Parathyroid hormone-related peptide and cardiovascular system. 1459 5

Vascular calcification is common among hemodialysis (HD) patients and contributes to the development of peripheral arterial disease. A 57-year-old Japanese man who had been on HD for 30 years was referred to us for severe pain with multiple ulcers on his toes and fingers. He was an ex-smoker and had no diabetes mellitus. On admission, he had ulcers on his big toes bilaterally and right 2nd - 4th fingers. Peripheral pulses were strong and his ankle-brachial pressure index was above 1.3. Laboratory data were as follows: calcium 9.9 mg/dl, albumin 3.3 g/dl, phosphate 3.0 mg/dl, Ca x P product 30, and parathyroid hormone 98 pg/ml. He had a parathyroidectomy in 1998 and 1999. X-rays of his hands and legs showed diffuse subcutaneous arteriolar calcification. Angiography revealed no local stenotic lesions. Despite intensive therapies including hyperbaric oxygen therapy, painful gangrene developed on his right big toe and the pain was so intense that he could not go to sleep in a supine position. We infused intravenous sodium thiosulfate (20 g) 3 times weekly, based on previous reports. Within 4 - 5 days, he experienced rapid and dramatic symptom relief. The score of the visual analogue pain scale improved from 10/10 - 2/10. The signs of ischemia, measured by transcutaneous partial oxygen pressure and thermography, improved significantly. During the infusion of sodium thiosulfate, the patient complained of nausea, vomiting and hyperosmia. These adverse symptoms were resolved after discontinuation of the infusion. Pain relief was sustained and he could walk after 2 weeks of infusion. Our case supports the use of sodium thiosulfate as a novel therapeutic choice for critical limb ischemia with severe vascular calcification in chronic HD patients.
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PMID:Successful management of critical limb ischemia with intravenous sodium thiosulfate in a chronic hemodialysis patient. 1693 72


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