Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study, the endonuclease inhibitor aurintricarboxylic acid (ATA) was examined for its ability to attenuate both acute and delayed excitotoxicity mediated through NMDA and non-NMDA glutamate receptors. Ex vivo embryonic chick retina, a model system frequently used for studies of excitotoxicity, was exposed to either 100 microM NMDA or kainate (KA) +/- various concentrations of ATA for 60 min, then allowed to recover for 24 h. Lactate dehydrogenase release into the medium and histology were assessed as measures of delayed toxicity. ATA attenuated lactate dehydrogenase release due to NMDA or KA in a dose-dependent manner. Histology revealed that ATA decreased the number of pyknotic profiles in response to either glutamate agonist. The mechanism of ATA protection was addressed. ATA was found to block NMDA- but not KA-mediated 22Na+ influx and cyclic GMP formation. In membrane binding studies, ATA was relatively selective for displacement at the NMDA receptor. The IC50 values for displacement of [3H]CGS 19755, alpha-[3H]amino-3-hydroxy-5-methylisoxazole-4-propionic acid ([3H]AMPA), or [3H]KA were 29.9 +/- 1.3, 313 +/- 46, and > 1,000 microM +/- SEM, respectively. ATA also fully attenuated NMDA-induced and partially attenuated KA-induced acute excitotoxicity as monitored histologically by tissue swelling and by the increase in GABA in the medium. Temporal studies of ATA efficacy indicated that ATA needed to be present during NMDA exposure to afford protection but, versus KA, was equally effective if administered immediately after KA exposure. Questions regarding the cellular penetration of ATA were raised because incubation with 100 microM ATA for 60 min had no effect on lactate formation or [3H]leucine incorporation into trichloroacetic acid-precipitable material, even though, in cell-free systems, ATA is a potent inhibitor of phosphofructokinase activity and protein synthesis. These studies demonstrate that ATA can protect against excitotoxicity mediated through NMDA or non-NMDA glutamate receptors. The mechanism of protection versus NMDA is through interruption of NMDA receptor interactions. ATA has no direct effect at the KA receptor; thus, its mechanism of protection versus KA is distinct from that versus NMDA and is, at present, unknown.
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PMID:Excitotoxicity at both NMDA and non-NMDA glutamate receptors is antagonized by aurintricarboxylic acid: evidence for differing mechanisms of action. 789 Nov 4

Cyclophosphamide (CYC) is a metabolically activated, DNA-alkylating, antitumor agent that causes pulmonary fibrosis. BALB/cN (B) mice are sensitive and C57Bl/6N (C) mice are resistant to CYC-induced fibrosis. Pulmonary bioactivation may contribute to strain sensitivity. Therefore, we tested the intrinsic susceptibility of murine lung slices to cell injury by direct exposure to CYC for 2-8 hr. Injury was measured by release of lactate dehydrogenase (LDH). DNA damage activates the nuclear enzyme poly(ADP-ribose) polymerase (PAP, EC 2.4.2.30), causing depletion of its substrate, NAD. NAD can also be decreased by phosphorylation to NADP, as seen with oxidative stress. Depletion of NAD can lead to loss of ATP. Thus, we measured LDH release, PAP activation, NAD, NADP and ATP in slices incubated with or without the PAP-inhibitor, 3-aminobenzamide (3-AB). CYC (0.1 to 1.0 mg/mL for 4-8 hr) caused LDH release in slices from both murine strains, but LDH release was significantly greater in B lung slices than in C slices. After an 8-hr incubation 63.9 +/- 3.7% (mean +/- SEM) of total LDH was released from B lung slices with 1.0 mg CYC/mL, whereas only 45.8 +/- 2.6% was released from C lung slices (P < 0.05). 3-AB reduced LDH release to 44.7 +/- 2.4% in B slices and 28.1 +/- 2.0% in C slices (P < 0.05 vs CYC only). PAP activity in nuclei isolated from CYC-treated B lung slices was increased 2- to 4-fold after 2 hr of incubation with 0.5 and 1.0 mg CYC/mL. PAP activation was delayed and reduced with incubation in 3-AB. PAP was activated 2-fold in nuclei from C slices treated with 0.5 mg CYC/mL for 2 hr. NAD was decreased at 2 and 4 hr in B slices treated with 0.5 and 1.0 mg CYC/mL, and at 4 hr with 0.1 mg CYC/mL. NAD depletion occurred only at 4 hr in the resistant C slices treated with 1.0 mg CYC/mL. CYC increased NADP by a similar extent in B and C lung slices. In B slices, NAD losses were approximately 4 times the increases in NADP. CYC did not decrease ATP in B slices and ATP dropped 25% only after 4 hr in the resistant C slices. We conclude that CYC is directly toxic to lung tissue and observe that strain sensitivity in vitro mirrors the sensitivity to fibrosis in vivo. PAP activation and oxidative stress may contribute to this toxicity.
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PMID:Acute pneumocyte injury, poly(ADP-ribose) polymerase activity, and pyridine nucleotide levels after in vitro exposure of murine lung slices to cyclophosphamide. 798 Jun 45

Effects of and recovery from continuous wear of four rigid gas permeable (RGP) contact lenses was assessed by noninvasive measurement of lactate dehydrogenase (LDH) activity and isozyme pattern in rabbit tears. Oxygen transmissibility (Dk/L) of lenses used was 27, 44, 84, and 97 x 10(-9) (cm/s)(ml O2/ml mm Hg); lens thickness (0.15 mm) and diameter (14.0 mm) were standardized. Lenses were worn continuously for 90 days; recovery was assessed 30 days after cessation of lens wear. LDH activity was measured by UV rate assay; isozyme subtypes were determined by agarose gel electrophoresis. Light and scanning electron microscopy (LM, SEM) were used with the determination of total protein as additional measures of lens effects. LDH levels were inversely correlated with lens Dk/L values; low Dk/L values increased the anaerobic (LDH4,5)/aerobic (LDH1,2,3) subtypen ratio indicating in vivo metabolic shift. SEM observations were consistent with these results. There was no significant difference in the total cell content of tears or total tear protein levels between control and RGP test-wear groups. Measurement of tear LDH activity and isozyme ratios appears to provide a sensitive, noninvasive assessment of the effects of RGP lens-induced hypoxia over time on the corneal surface. A level of Dk/L of > or = 84 appears best for maintaining corneal physiology during extended wear. Recovery from chronic lens-induced hypoxia is characterized by a return to normal tear LDH levels and isozyme subtypes.
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PMID:Effects of rigid lens extended wear on lactate dehydrogenase activity and isozymes in rabbit tears. 799 67

We evaluated the ability of alpha-phenyl-tert-butyl nitrone (PBN) to trap free radicals and to protect the rat myocardium during ischemia and reperfusion. Isolated bicarbonate buffer-perfused hearts (n = 8) were subjected to 20 min global ischemia (37 degrees C) followed by reperfusion with 0.4 to 4.0 mM PBN. Coronary effluent containing the PBN adduct was extracted in toluene. Electron spin resonance analysis of the toluene extract revealed a PBN-hydroxyl adduct. To verify this assignment, a Fenton system was used to generate an authentic PBN-hydroxyl adduct (n = 8), which yielded the same ESR spectra as the reperfusion-derived adduct. The structure of the adduct formed in the Fenton system was confirmed by gas chromatography-mass spectrometry. The ESR parameters of the PBN-hydroxyl adduct were exquisitely sensitive to solvent polarity during extraction of the adduct. Extraction of an authentic PBN-hydroxyl adduct into chloroform, chloroform:methanol, and toluene closely matched the ESR parameters obtained during reperfusion of ischemic myocardium in other animal models. To determine whether PBN could confer any protective effect during ischemia or reperfusion, hearts (n = 8/group) were subjected to 35 min global ischemia at 37 degrees C with the St. Thomas' II cardioplegic solution followed by 30 min reperfusion. Percent recovery (mean +/- SEM) of developed pressure, rate pressure product, and leakage of lactate dehydrogenase during reperfusion in control hearts were 58 +/- 3%, 48 +/- 4% and 3.2 +/- 0.5 IU/15 min/g wet wt. PBN at a concentration of 0.4 mM or 4.0 mM when present either during ischemia alone or reperfusion alone did not exert any effect upon recovery of developed pressure, rate pressure product or post-ischemic enzyme leakage. We conclude that PBN fails to improve contractile recovery and reduce enzyme leakage during reperfusion of myocardium subjected to global ischemia.
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PMID:Lack of protection of PBN in isolated heart during ischemia and reperfusion: implications for radical scavenging mechanism. 801 39

Bronchoalveolar lavage (BAL) has gained widespread use as a tool for investigating human lung diseases. In certain cases, it can be useful to obtain BAL material in a serial manner. There is convincing evidence from experimental and clinical studies that BAL can cause influx of neutrophils into the bronchoalveolar space. However, conflicting data have been reported on whether this side effect of BAL also affects previously nonlavaged lung areas. In addition, there is little information available on whether multiple repetitive BAL procedures cause damage to lung tissue. To reexamine the short-term effects of serial BAL procedures, the left lung of 10 cynomolgus monkeys was lavaged with five 20-ml aliquots of saline four times at 24-h intervals (Group A). 72 h after the initial BAL, the right lung was lavaged as a control. The percentage of neutrophils increased significantly (p < 0.05), with the greatest effect seen at 48 h (30.7 +/- 5.8 versus 0.8 +/- 0.3%, mean +/- SEM). No significant changes were observed in the control BAL of the right lung at 72 h. A multidisciplinary approach was used to assess the long-term effects of multiple BAL procedures. BAL was performed 14 times over 26 mo at 2-mo intervals (Group B, n = 5). The right lung was lavaged as a control 25 mo after the initial BAL. In addition to standard cellular BAL parameters, the concentrations of fibronectin, procollagen III amino-terminal peptide-related antigen, total phospholipids, and lactate dehydrogenase activity were measured.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Short-term and long-term effects of serial bronchoalveolar lavages in a nonhuman primate model. 802 42

Peripheral ischemia was induced in the rabbit by occlusion of the left iliac artery for 6 hr, followed by 24 hr of reperfusion. Biochemical and morphological investigations were performed to evaluate the extent of vascular and tissue injury. Blood samples for plasma enzyme determinations (creatine kinase (CK) and lactate dehydrogenase (LDH) activities) were obtained at times t = 0, t = 6, t = 30 hr. Plasma CK and LDH activities in ischemic animals were approximately twice as high as those in sham-operated animals at the end of reperfusion, although no difference was observed at the end of the period of ischemia. Morphological and morphometric analysis of extensor digitorum longus muscle from ischemic animals showed a reduction in the number of patent capillary vessels per muscle fiber (1.54 +/- 0.1 and 1.04 +/- 0.09, P < 0.05, in sham and ischemic groups, respectively; mean +/- SEM). In addition, the number of microvilli on endothelial surfaces were considerably increased in the ischemic group (0.14 +/- 0.02 and 0.41 +/- 0.01 microns -2, P < 0.001, in sham and ischemic groups, respectively). A great number of adhered leucocytes were found on the vessel surface with some leucocytes having migrated through the vessel wall. Microcirculatory damage was accompanied by the formation of microthrombi which sometimes occluded the entire vessel lumen. The infusion of 1 mg/kg/hr of cloricromene for 6 hr prevented ischemic injury in microvessels and also prevented swelling of muscle mitochondria. In the treated group the number of patent capillaries per muscle fiber was very similar to that found in sham-operated animals (1.49 +/- 0.08; P < 0.01 vs. ischemic control). In conclusion, several different cell types are involved in the pathophysiological changes which occur in microvessels during ischemia/reperfusion injury. Pharmacological interventions, which inhibit the interactions of blood cells with endothelium, may be of value in the treatment of peripheral ischemia/reperfusion injury.
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PMID:Changes in vessel ultrastructure during ischemia and reperfusion of rabbit hindlimb: implications for therapeutic intervention. 841 53

It is our experience that warm dissection in the porta hepatis as well as extensive organ mobilization during combined pancreas-liver procurements may cause posttransplant dysfunction of the liver. To avoid this, we recently utilized a rapid en bloc procurement technique with minimal warm dissection and division of the liver and pancreas ex vivo. Fifteen procurements were performed using this rapid en bloc technique; seventeen procurements involved extensive dissection followed by sequential in situ procurement of the liver and pancreas grafts. The control group consisted of 15 age-matched patients who received livers when no pancreas was harvested. Dissection time was 157 +/- 13 min (mean +/- SEM) in the in situ group, 78 +/- 3 min in the en bloc group (P<0.02), and 51 +/- 6 min in the liver only group (P<0.02). There was no difference in donor age, cold ischemia time, or recipient United Network for Organ Sharing status. Pancreata obtained using the en bloc technique all had immediate function and there were no episodes of acute pancreatitis. Early liver graft function, as assessed by lactate dehydrogenase, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, and total bilirubin levels, was significantly lower in the en bloc and liver only group when compared with the in situ group. The total hospital stay was also significantly lower in these groups. We conclude that the rapid en bloc technique decreases operative time during the donor operation. Procurement-related injury to the liver graft is minimized without compromising pancreas graft function.
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PMID:Rapid en bloc technique for pancreas-liver procurement. Improved early liver function. 866 5

The uptake of hyaluronic acid (HA) was used to assess preservation damage to sinusoidal endothelial cells (SEC) during cold storage and subsequent normothermic reperfusion of rat livers. After 8, 16, 24, and 48 h storage in University of Wisconsin (UW) solution, livers were gravity-flushed via the portal vein with a standard volume of cold UW solution containing 50 micrograms/l HA. The effluent was collected for analysis of HA, aspartate aminotransferase (AST), and lactate dehydrogenase (LDH). The mean uptake of HA at 0 h was 59.1% +/- 4.6% (mean +/- SEM). After 8 h of storage, HA uptake was similar (55.5% +/- 7.3%), whereas after 16 h of storage it was reduced to 34.7% +/- 5.8%. At 24 and 48 h of storage, no uptake of HA was found. In a second series of experiments, livers were stored in UW solution and subsequently reperfused for 90 min with a Krebs-Henseleit solution (37 degrees C) in a recirculating system containing 150 micrograms/l HA. Following 8 h of storage, 34.6% +/- 8.0% of the initial HA concentration was taken up from the perfusate. After 16 and 24 h of storage, no uptake of HA was found. The results of this study indicate that damage to SEC occurs progressively during storage, leading to zero uptake of HA by the rat livers at 24 h of cold ischemia time. Additional reperfusion injury to the SEC was demonstrated by the reduced ability of the SEC to take up HA following normothermic reperfusion. The uptake of exogenous HA in preserved livers, used as a tool to assess SEC injury, enables the detection of early preservation damage.
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PMID:Hyaluronic acid uptake in the assessment of sinusoidal endothelial cell damage after cold storage and normothermic reperfusion of rat livers. 887 86

High levels of lactate dehydrogenase (LDH; EC 1. 1. 1. 27) activity have been detected in the filarial worm Molinema dessetae. The two major LDH isoenzymes (LDH1 and LDH2) from female worms were purified by successive chromatography on diethylaminoethyl (DEAE)-Sepharose, carboxymethyl (CM)-Sepharose, and hydroxyapatite columns followed by fast protein liquid chromatography (FPLC)-gel filtration. LDH1 and LDH2 isoenzymes were found to be dimers with subunits of 58 kDa. They had similar properties with regard to substrate and coenzyme affinity. The apparent Michaelis constants (K(m) values; mean +/- SEM, n = 10) were 0.34 +/- 0.04 mM for pyruvate, 0.25 +/- 0.02 mM for reduced nicotinamide adenine dinucleotide (NADH), 2.5 +/- 0.21 mM for lactate, and 0.18 +/- 0.02 mM for NAD, which suggested that pyruvate reduction was the favored reaction. LDH1 and LDH2 were affected by p-chloromercuribenzoate and Hg2+, and such inhibitory effects could be reversed by the addition of thiol compounds (L-cysteine or beta-mercaptoethanol) as observed for mammalian LDH. Oxalate acted as a noncompetitive inhibitor of pyruvate reduction (Ki = 4.7 +/- 0.35 mM; mean +/- SEM, n = 10) and as a competitive inhibitor with lactate (Ki = 2.3 +/- 0.21 mM), whereas oxamate acted as a competitive inhibitor with pyruvate (Ki = 3.3 +/- 0.28 mM) and was noncompetitive with lactate (Ki = 19 +/- 1.2 mM). These substrate analogues exerted similar effects on mammalian LDH, but the inhibition constants were significantly different. The existence of structural and kinetic differences between mammal and filarial LDH isoenzymes prompted us to evaluate them as targets for chemotherapeutic attack.
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PMID:Purification and characterization of lactate dehydrogenase isoenzymes 1 and 2 from Molinema dessetae (Nematoda:Filarioidea). 889

In animals models, exposure of the brain, heart, or kidneys to sublethal ischemia induces tolerance for subsequent ischemia. However, the ability of human renal cells to undergo hypoxic preconditioning has not been evaluated. In addition, it is unclear if renal ischemic preconditioning induces resistance at the cellular level, or if preconditioning is a result of altered postischemic hemodynamics or the azotemic environment. In this study, we tested the ability of cultured human proximal tubular epithelial cells (PTEC) to undergo hypoxic preconditioning at the cellular level. Hypoxia was induced by incubating cells in an anaerobic incubator in glucose-free buffer (combined oxygen-glucose deprivation; COGD). Cell injury was assessed by lactate dehydrogenase (LDH) efflux, release of arachidonic acid metabolites, and light microscopy. PTEC preconditioned with 12 h of COGD and a 24-h recovery period had less LDH efflux than control PTEC after subsequent exposure to 20 h of COGD (15.0 +/- 2.5% vs. 44.0 +/- 3.4%, p < 0.05). Preconditioned PTEC also retained relatively normal morphology and had less release of arachidonic acid metabolites than control PTEC. Because renal ischemia is characterized predominately by tubular injury with relative sparing of the glomerulus, we determined if PTEC are more susceptible to hypoxic injury than glomerular cells. For further comparison, we also assessed the susceptibility to hypoxia of the porcine tubular epithelial cell line LLC-PK1. After exposure to 18 h of COGD, LDH efflux from PTEC (25.5 +/- 3.3%, mean +/- SEM) was lower than from LLC-PK1 cells (47.6 +/- 4.0%; p < 0.01), but not mesangial cells (22.7 +/- 5.0%) or glomerular endothelial cells (38.2 +/- 6.2%). In conclusion, we have demonstrated that cultured PTEC are as resistant to hypoxic injury as glomerular cells, and that PTEC attain cytoresistance after hypoxic preconditioning. Characterization of the molecular changes that occur in human PTEC after hypoxic preconditioning may reveal innate survival mechanisms that can be manipulated to promote protection from renal ischemia in patients.
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PMID:Susceptibility of human proximal tubular cells to hypoxia: effect of hypoxic preconditioning and comparison to glomerular cells. 904 51


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