Protective effect of L-carnitine on renal ischaemia-reperfusion injury in the rat

This study was designed to investigate the effect of L-carnitine in ischaemia and reperfusion of the rat kidney. Rats were randomly allocated into three groups. Group I (control group; n = 6) received no treatment. Group II (isotonic saline group; n = 6), received 2 ml of isotonic saline 15 min before the renal ischaemia, and group III (carnitine group; n = 6) received L-carnitine hydrochloride (100 mg kg(-1)) intraperitoneally. At the end of the reperfusion period, rats were sacrificed. Tissue malondialdehyde level (MDA), myeloperoxidase (MPO) activity, and nitrite/nitrate (NO) level of renal tissue were measured to evaluate the lipid peroxidation, neutrophil function, and nitric oxide metabolism, respectively. The tissue levels of MDA, MPO and NO were lower in group III (71.8 +/- 8.4, 172.1 +/- 27.4 U g(-1) tissue, 76.3 +/- 29.7 micromol l(-1) respectively) than levels in groups I (103.4 +/- 13.4 nmol g(-1), 325.9 +/- 20.2 U g(-1) tissue, 144.5 +/- 39.2 micromol l(-1), respectively) and II (103.5 +/- 11.4 nmol g(-1), 317.1 +/- 41.5 U g(-1) tissue, 148.9 +/- 23.9 micromol l(-1), respectively). It is shown that carnitine protects kidney tissue against ischaemia-reperfusion injury.     

Donor heart preservation with iloprost supplemented St. Thomas Hospital cardioplegic solution in isolated rat hearts

This study was designed to assess the influence of St. Thomas Hospital cardioplegic solution (St. Th.) on heart preservation in rat hearts subjected to 6h ischemia when supplemented with iloprost. In the control group (n=8), nothing was added to St. Th., whereas 10 or 1000 nmol L(-1) iloprost was added in the second (n=7) and third (n=8) groups, respectively. Mechanical contraction parameters, cardiac tissue damage and oxidative stress markers were evaluated. The 10 nmol/L iloprost group peak systolic pressure (71.0+/-30.9 versus 41.0+/-9.4 mm Hg) and -dp/dtmax (1103.8+/-94.3 versus 678.6+/-156.8 mm Hg s(-1)) were significantly higher than control group at 30 min of reperfusion (p<0.05). Iloprost supplemented groups had higher GSH and catalase levels of coronary perfusate at reperfusion, in comparison with initial values (p<0.05). AST, CK, CK-MB values increased at 0 min of reperfusion and cTnI values at 45 min of reperfusion (p<0.05) in all groups with no difference between groups. According to our results, iloprost supplementation had mild but significant improvement in postischemic values in mechanical and oxidative stress parameters, resulting in better heart preservation.     

Soluble complement receptor type 1 ameliorates the local and remote organ injury after intestinal ischemia-reperfusion in the rat.

We examined the role of C activation in ischemia reperfusion injury by inhibiting C activation in a rat model of mesenteric arterial occlusion. In anesthetized rats, 60 min of mesenteric arterial occlusion was followed by 3 h of reperfusion. PBS alone or containing soluble C receptor 1 (3 or 6 mg) was administered i.v. Controls underwent laparotomy without ischemia. Relative serum C activities were assessed by hemolytic assay, neutrophil (polymorphonuclear leukocyte) sequestration by tissue content of myeloperoxidase (MPO) activity, intestinal mucosal injury by histologic grading, lung vascular permeability by the ratio of bronchoalveolar lavage to blood concentration of radiolabeled BSA, and endothelial cell injury was quantified by measurement of plasma factor VIII-related Ag. After reperfusion, PBS-treated animals had increased intestinal MPO (0.048 +/- 0.007 U/g) compared to sham (0.022 +/- 0.005 U/g (p less than 0.05)) and intestinal mucosal injury score (2.490 +/- 0.221) compared to sham (0.331 +/- 0.045 (p less than 0.05)). Treatment with 6 mg soluble C receptor 1 15 min before reperfusion reduced intestinal MPO (0.017 +/- 0.003 U/g (p less than 0.05)) and mucosal injury (1.733 +/- 0.168 (p less than 0.05)) compared to PBS control. PBS-treated animals also demonstrated increased lung MPO (0.314 +/- 0.025 U/g vs 0.085 +/- 0.018 in sham (p less than 0.05)) and increased lung permeability (bronchoalveolar lavage/blood cpm 11.32 +/- 1.35 x 10(-3) vs sham 2.22 +/- 0.19 x 10(-3) (p less than 0.05)). Treatment with 6 mg soluble C receptor 1 15 min before reperfusion or at reperfusion reduced the lung permeability (bronchoalveolar lavage/blood cpm 3.90 +/- 0.79 x 10(-3) and 5.08 +/- 0.75, respectively (both p less than 0.05)) compared to PBS control, but did not reduce lung MPO (0.342 +/- 0.031 U/g and 0.246 +/- 0.025), respectively. Treatment with sCR1 also reduced the release of factor VIII-related Ag, 5-day mortality, and C hemolytic activity. In this model, C is a major mediator of intestinal injury and extraintestinal injury.     

The reduction of myocardial damage and leukocyte polymorphonuclear accumulation following coronary artery occlusion by the tyrosine kinase inhibitor tyrphostin AG 556

We investigated the effects of tyrophostin AG 556, a tyrosine kinase inhibitor, on the phenomenon of leukocyte accumulation during ischaemia and reperfusion of the myocardium. Male anaesthetized rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5 h reperfusion (MI/R). Sham myocardial ischaemia-reperfusion rats (Sham MI/R) were used as controls. Myocardial necrosis, myocardial myeloperoxidase activity (MPO), serum creatinine phosphokinase activity (CPK) serum Tumor Necrosis Factor (TNF-alpha) and Interleukin 6 (IL-6), cardiac intercellular adhesion molecule-1 (ICAM-1) and TNF-alpha expression and myocardial contractility (left ventricle dP/dt(max)) were evaluated. Myocardial ischaemia plus reperfusion in untreated rats produced marked myocardial necrosis, increased serum CPK activity (196.5 +/- 19 U/100 ml, at the end of reperfusion) and myeloperoxidase activity (MPO, a marker of leukocyte accumulation) both in the area-at-risk (4.5 +/- 0.5 U/g/tissue) and in necrotic area (8.2 +/- 1.2 U/g/tissue), reduced myocardial contractility (1,706 +/- 52 mmHg/s, at the end of reperfusion) and induced a marked increase in the serum levels of TNF-alpha (1,950 +/- 97 pg/ml, at 1 h of reperfusion) and IL-6 (998 +/- 16 U/ml, at the end of reperfusion). Finally, myocardial ischaemia-reperfusion injury also increased cardiac mRNA for TNF-alpha and ICAM-1 in the myocardium-at risk. Tyrphostin AG 556 (0.5, 1 and 2 mg/kg subcutaneously 5 min after the onset of reperfusion) lowered myocardial necrosis and myeloperoxidase activity in the area-at-risk (1.5 +/- 0.2 U/g/tissue, following the highest dose) and in necrotic area (2.9 +/- 0.3 U/g/tissue following the highest dose), decreased serum CPK activity (96 +/- 9 U/100 ml, at the end of reperfusion), lowered serum TNF-alpha and IL-6, increased myocardial contractility (2,096 +/- 88 mmHg s, at the end of reperfusion) and reduced cardiac mRNA levels for TNF-alpha and ICAM-1. The present data suggest that tyrosine kinase inhibitors protect against myocardial ischaemia-reperfusion injury by reducing leukocyte accumulation to the ischaemic myocardium.     

Attenuation of intestinal ischemia/reperfusion induced liver and lung injury by intraperitoneal administration of (-)-epigallocatechin-3-gallate

The aim of this study was to evaluate the effect of ( - )-epigallocatechin-3-gallate (EGCG), a natural antioxidant, on liver and lungs after warm intestinal ischemia/reperfusion (I/R). Thirty male Wistar rats were equally divided into a sham-operation group, an intestinal I/R group and an intestinal I/R group pretreated with EGCG intraperitoneally. Intestinal ischemia was induced by occlusion of the superior mesenteric artery for 60 min followed by reperfusion for 120 min. Immediately after reperfusion, liver, lung and blood samples were collected and analyzed. Results showed that intestinal I/R increased the levels of aspartate (AST) and alanine (ALT) transaminase in serum to 987 and 752 IU/l, respectively. Malondialdehyde (MDA) increased in liver to 1.524 nmol/g in the group subjected to intestinal I/R compared to 0.995 nmol/g in the sham operation group. MDA was also increased in lungs to 1.581 nmol/g compared to 0.896 nmol/g in the sham operation group. Myeloperoxidase (MPO) increased in liver, after intestinal I/R, to 5.16 U/g compared to 1.59 U/g in the sham operation group. MPO was also increased in lungs to 3.89 U/g compared to 1.65 U/g in the sham operation group. Pretreatment with EGCG decreased serum levels of AST and ALT to 236 and 178 IU/l, respectively. It also decreased mean MDA levels in liver and lungs to 1.061 and 1.008 nmol/g, respectively, and mean MPO levels in liver and lungs to 1.88 and 1.71 U/g, respectively. Light microscopy and transmission electron microscopy examinations showed significant alteration in liver and lungs and protection of liver and lung parenchyma in the animals treated with EGCG.     

Oxidative stress is decreased in off-pump versus on-pump coronary artery surgery

Oxidative stress occurs in patients undergoing coronary artery bypass operation. The aim of this study was to investigate the difference in oxidative stress in off-pump versus on-pump coronary artery bypass surgery. In the present study, in serial blood samples, plasma malondialdehyde (MDA) as index of lipid peroxidation, red blood cells glutathione peroxidase (GPx) and superoxide dismutase (SOD) were measured to compare the extent of oxidative stress in 30 patients undergoing OPCAB (off-pump coronary artery bypass grafting), 12 patients undergoing CABG (on-pump coronary artery bypass grafting) and 18 healthy controls. In CABG group, MDA levels increased significantly from 2.87 +/- 0.62 nmol/mL before anesthesia and 2.87 +/- 0.65 nmol/mL after anesthesia to 3.05 +/- 0.66 nmol/mL after ischemia (p < 0.05). Similarly, SOD levels also elevated significantly from 661.58 +/- 78.70 U/g Hb before anesthesia and 659.42 +/- 81.21 U/g Hb anesthesia induction to 678.08 +/- 75.80 U/g Hb after ischemia (p < 0.01, p < 0.01, respectively). In OPCAB group, only SOD levels increased from 581.73 +/- 86.24 U/g Hb anesthesia induction to 590.90 +/- 88.90 U/g Hb after reperfusion (p < 0.05). Glutathione peroxidase levels were not changed according to blood collection times in both of CABG group or OPCAB group (p > 0.05). Our results show that only mild signs of oxidative stress is found after reperfusion in OPCAB operation compared with CABG operation. Further studies are needed in order to confirm this hypothesis.     

Lipid peroxidation inhibition reduces NF-kappaB activation and attenuates cerulein-induced pancreatitis

Increased lipid peroxidation, enhanced nuclear factor kappa-B (NF-kappaB) activation and augmented tumor necrosis factor-alpha (TNF-alpha) production have been implicated in cerulein-induced pancreatitis. We investigated whether lipid peroxidation inhibition might reduce NF-kappaB activation and the inflammatory response in cerulein-induced pancreatitis. Male Sprague-Dawley rats of 230-250g body weight received administration of cerulein (80 microg/kg s.c. for each of four injections at hourly intervals). A control group received four s.c. injections of 0.9% saline at hourly intervals. Animals were randomized to receive either raxofelast, an inhibitor of lipid peroxidation (20 mg/kg i.p. administered with the first cerulein injection) or its vehicle (1 ml/kg of a 10% DMSO/NaCl solution). All these rats were sacrificed 2 h after the last injection of either cerulein or its vehicle. Raxofelast administration (20 mg/kg i.p. with the first cerulein) significantly reduced malondialdehyde (MDA) levels, an index of lipid peroxidation (CER + DMSO = 3.075 +/- 0.54 micromol/g; CER + raxofelast = 0.693 +/- 0.18 micromol/g; p < 0.001), decreased myeloperoxidase (MPO) activity (CER + DMSO = 22.2 +/- 3.54 mU/g; CER + raxofelast = 9.07 +/- 2.05 mU/g, p < 0.01), increased glutathione levels (GSH) (CER + DMSO = 5.21 +/- 1.79 micromol/g; CER + raxofelast = 15.71 +/- 2.14 micronol/g; p < 0.001), and reduced acinar cell damage evaluated by means of histology and serum levels of both amylase (CER + DMSO = 4063 +/- 707.9 U/l; CER + raxofelast = 1198 +/- 214.4 U/l; p < 0.001), and lipase (CER + DMSO = 1654 +/- 330 U/l; CER + raxofelast = 386 +/- 118.2 U/l; p < 0.001), Furthermore, raxofelast reduced pancreatic NF-kappaB activation and the TNF-alpha mRNA levels and tissue content of mature protein in the pancreas. Indeed, lipid peroxidation inhibition might be considered a potential therapeutic approach to prevent the severe damage in acute pancreatitis.     

Octreotide ameliorates alendronate-induced gastric injury

Alendronate causes serious gastrointestinal adverse effects. The aim of this study was to investigate whether octreotide, a synthetic somatostatin analogue, improves the alendronate-induced gastric injury. Rats were administered 20mg/kg alendronate by gavage for 4 days, either alone or following treatment with octreotide (0.1 ng/kg, i.p.). On the last day, following drug administration, pilor ligation was performed and 2h later, rats were killed and stomachs were removed. Gastric acidity and tissue ulcer index values, lipid peroxidation (as assessed by malondialdehyde, MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity as well as the histologic appearance of the stomach tissues were determined. Chronic oral administration of alendronate induced significant gastric damage, increasing lipid peroxidation (37.1+/-3.2 nmol/g) and myeloperoxidase activity (57.6+/-3.7 U/g), while tissue glutathione levels (09.+/-0.1 micromol/g) decreased. Treatment with octreotide prevented this damage as well as the changes in biochemical parameters (MDA: 23.4+/-1.3 nmol/g; MPO: 31.68 U/g; GSH: 15.+/-0.1 micromol/g). Findings of the present study suggest that alendronate induces oxidative gastric damage by a local irritant effect, and that octreotide ameliorates this damage by inhibiting neutrophil infiltration and reducing lipid peroxidation. Therefore, its therapeutic role as a "ulcer healing" agent must be further elucidated in alendronate-induced gastric mucosal injury.     

Effect of thinner inhalation on lipid peroxidation and some antioxidant enzymes of people working with paint thinner

Paint thinner is a commonly used industrial solvent with considerable potential for abuse by inhalation. Paint thinner is taken into the body by inhalation or by contact with the skin. Paint thinner is oxidized gradually by cytochrome P450-dependent monooxygenase and consequently free radicals are produced. In the present study we measured plasma malondialdehyde (MDA, a product of lipid peroxidation) levels as an indicator of oxidative damage and activity levels of antioxidant enzymes gluthatione peroxidase (GSH-Px) and superoxide dismutase (SOD) in erythrocytes of a group of people (n = 18) working with paint thinner. The control group was composed of 18 healthy adults. There was a statistically significant (p < 0.001) increase in MDA (2.0+/-0.7 nmol ml(-1)) and GSH-Px (86.5+/-16.6 U g(-1) Hb) activity levels in people working with paint thinner compared with control subjects (MDA: 1.0+/-0.3 nmol ml(-1); GSH-Px: 53.9+/-14.5 U g(-1) Hb). Similarly, there was also an increase (p < 0.05) in the SOD levels (1079+/-214.6 U g(-1) Hb) of people working with paint thinner compared with controls (953.3+/-46.7 U g(-1) Hb). Based on our results, it can be concluded that paint thinner inhalation may increase lipid peroxidation and consequently induce antioxidant enzymes.     

Myeloperoxidase enhances nitric oxide catabolism during myocardial ischemia and reperfusion

Impaired microvascular function during myocardial ischemia and reperfusion is associated with recruitment of polymorphonuclear neutrophils (PMN) and has been attributed to decreased bioavailability of nitric oxide (NO). Whereas myeloperoxidase (MPO), a highly abundant, PMN-derived heme protein facilitates oxidative NO consumption and impairs vascular function in animal models of acute inflammation, its capacity to function in this regard during human myocardial ischemia and reperfusion remains unknown. Plasma samples from 30 consecutive patients (61 +/- 14 years, 80% male) presenting with acute myocardial infarction were collected 9 +/- 4 h after vessel recanalization and compared to plasma from healthy control subjects (n = 12). Plasma levels of MPO were higher in patients than in control subjects (1.4 +/- 0.9 vs 0.3 +/- 0.2 ng/mg protein, respectively, p < 0.0001). The addition of hydrogen peroxide to patient plasma resulted in accelerated rates of NO consumption compared to control subjects (0.53 +/- 0.25 vs 0.068 +/- 0.039 nM/s/mg protein, respectively, p < 0.0001). Myocardial tissue from patients with the same pathology revealed intense recruitment of MPO-positive PMN localized along infarct-related vessels as well as diffuse endothelial distribution of non-PMN-associated MPO immunoreactivity. Endothelium-dependent microvascular function, as assessed by an acetylcholine-dependent increase in forearm blood flow in 75 patients with symptomatic coronary artery disease, inversely correlated with MPO plasma levels (r = -0.75, p < 0.005). Plasma from patients undergoing myocardial reperfusion contained increased levels of MPO, which catalytically consumed NO in the presence of H(2)O(2). Given the correlation between intravascular MPO levels and forearm vasomotor function in patients with coronary artery disease, MPO appears to be an important modulator of vasomotor function in inflammatory vascular disease and a potential therapeutic target for treatment.     

Erythropoietin protects the intestine against ischemia/ reperfusion injury in rats

Previous studies have shown that erythropoietin (EPO) has protective effects against ischemia/reperfusion (I/R) injury in several tissues. The aim of this study was to determine whether EPO could prevent intestinal tissue injury induced by I/R. Wistar rats were subjected to intestinal ischemia (30 min) and reperfusion (60 min). A single dose of EPO (5000 U/kg) was administered intraperitoneally at two different time points: either at five minutes before the onset of ischemia or at the onset of reperfusion. At the end of the reperfusion period, jejunum was removed for examinations. Myeloperoxidase (MPO), malondialdehyde (MDA), and antioxidant defense system were assessed by biochemical analyses. Histological evaluation was performed according to the Chiu scoring method. Endothelial nitric oxide synthase (eNOS) was demonstrated by immunohistochemistry. Apoptotic cells were determined by TUNEL staining. Compared with the sham, I/R caused intestinal tissue injury (Chiu score, 3+/-0.36 vs 0.4+/-0.24, P<0.01) and was accompanied by increases in MDA levels (0.747+/-0.076 vs 0.492+/-0.033, P<0.05), MPO activity (10.51+/-1.87 vs 4.3+/-0.45, P<0.05), intensity of eNOS immunolabelling (3+/-0.4 vs 1.3+/-0.33, P<0.05), the number of TUNEL-positive cells (20.4+/-2.6 vs 4.6+/-1.2, P<0.001), and a decrease in catalase activity (16.83+/-2.6 vs 43.15+/-4.7, P<0.01). Compared with the vehicle-treated I/R, EPO improved tissue injury; decreased the intensity of eNOS immunolabelling (1.6+/-0.24 vs 3+/-0.4, P<0.05), the number of TUNEL-positive cells (9.2+/-2.7 vs 20.4+/-2.6, P<0.01), and the high histological scores (1+/-0.51 vs 3+/-0.36, P<0.01), and increased catalase activity (42.85+/-6 vs 16.83+/-2.6, P<0.01) when given before ischemia, while it was found to have decreased the levels of MDA (0.483+/-0.025 vs 0.747+/-0.076, P<0.05) and MPO activity (3.86+/-0.76 vs 10.51+/-1.87, P<0.05), intensity of eNOS immunolabelling (1.4+/-0.24 vs 3+/-0.4, P<0.01), the number of TUNEL-positive cells (9.1+/-3 vs 20.4+/-2.6, P<0.01), and the number of high histological scores (1.16+/-0.4 vs 3+/-0.36, P<0.05) when given at the onset of reperfusion. These results demonstrate that EPO protects against intestinal I/R injury in rats by reducing oxidative stress and apoptosis. We attributed this beneficial effect to the antioxidative properties of EPO.     

一氧化碳吸入对脂多糖诱导大鼠急性肺损伤的保护作用

血红素氧合酶(heme oxygenase,HO)降解血红素的主要代谢产物一氧化碳(carbon monoxide,CO)具有抗氧化、抗炎症和抑制细胞凋亡作用,而脂多糖(lipopolysaccharide,LPS)诱导的肺组织过氧化、炎症性损伤及大量肺泡上皮和血管内皮细胞凋亡正是导致肺损伤(lung injury,LI)的关键.由此我们猜想,CO有可能通过上述机制对LI起保护作用.通过静脉注入LPS(5 mg/kg体重)诱导大鼠LI,观察吸入室内空气或2.5×10-4(V/V)CO 3 h后,肺氧化酶学、炎症细胞因子、细胞凋亡、HO-1表达及组织形态学变化.结果显示,静脉注入LPS诱导LI后,CO吸入组大鼠肺肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)、白细胞介素6(interlukin-6,IL-6)、丙二醛(maleic dialdehyde,MDA)、髓过氧化物酶(myeloperoxidase,MPO)和细胞凋亡分别为(0.91±0.25)pg/mg蛋白、(0.64±0.05)pg/mg蛋白、(1.02±0.23)nmol/mg蛋白、(7.18±1.62)U/mg蛋白、(1.60±0.34)%,均显著低于LI组的(1.48±0.23)pg/mg蛋白、(1.16±0.26)pg/mg蛋白、(1.27+0.33)nmol/mg蛋白、(8.16+1.49)U/mg蛋白、(3.18±0.51)%(P＜0.05).CO吸入组HO-1、白细胞介素10(interlukin-10,IL-10)表达和超氧化物歧化酶(superoxide dismutase,SOD)活性分别为(5.43±0.92)、(0.26±0.07)pg/mg蛋白、(60.09±10.21)U/mg蛋白,它们均显著高于LI组的(3.08±0.82)、(0.15±0.03)pg/mg蛋白、(50.98±6.88)U/mg蛋白(P＜0.05).与LI组相比,CO吸入组肺损伤减轻.研究结果表明,低浓度CO吸入通过抗氧化、抗炎症、抑制细胞凋亡、上调HO-1表达而减轻LPS诱导的肺损伤.     

Levetiracetam protects against kainic acid-induced toxicity

We investigated the Levetiracetam (LVT) ability to protect the brain against kainic acid (KA) induced neurotoxicity. Brain injury was induced by intraperitoneal administration of KA (10 mg/kg). Sham brain injury rats were used as controls. Animals were randomized to receive either LVT (50 mg/kg) or its vehicle (1 ml/kg) 30 min. before KA administration. Animals were sacrificed 6 hours after KA injection to measure brain malonildialdehyde (MDA), glutathione levels (GSH) and the mRNA for interleukin-1beta (IL-1beta) in the cortex and in the diencephalon. Behavioral changes were also monitored. Intraperitoneal administration of LVT decreased significantly MDA in the cortex (KA + vehicle = 0.25 +/- 0.03 nmol/mg protein; KA + LVT = 0.13 +/- 0.01 nmol/mg protein; P < 0.005), and in the diencephalons (KA + vehicle = 1,01 +/- 0.2 nmol/mg protein; KA + LVT = 0,33 +/- 0,08 nmol/mg protein; P < 0.005), prevented the brain loss of GSH in both cortex (KA + vehicle = 5 +/- 1 micromol/g protein; KA + LVT = 15 +/- 2 micromol/g protein; P < 0.005) and diencephalons (KA + vehicle = 9 +/- 0.8 micromol/g protein; KA + LVT = 13 +/- 0.3 micromol/g protein; P < 0.05), reduced brain IL-1beta mRNA and markedly controlled seizures. Histological analysis showed a reduction of cell damage in LVT treated samples. The present data indicate that LVT displays neuro-protective effects against KA induced brain toxicity and suggest that these effects are mediated, at least in part, by inhibition of lipid peroxidation.     

Exogenous amino acids stimulate human muscle anabolism without interfering with the response to mixed meal ingestion

We sought to determine whether ingestion of a between-meal supplement containing 30 g of carbohydrate and 15 g of essential amino acids (CAA) altered the metabolic response to a nutritionally mixed meal in healthy, recreationally active male volunteers. A control group (CON; n = 6, 38 +/- 8 yr, 86 +/- 10 kg, 179 +/- 3 cm) received a liquid mixed meal [protein, 23.4 +/- 1.0 g (essential amino acids, 14.7 +/- 0.7 g); carbohydrate, 126.6 +/- 4.0 g; fat, 30.3 +/- 2.8 g] every 5 h (0830, 1330, 1830). The experimental group (SUP; n = 7, 36 +/- 10 yr, 87 +/- 12 kg, 180 +/- 3 cm) consumed the same meals but, in addition, were given CAA supplements (1100, 1600, 2100). Net phenylalanine balance (NB) and fractional synthetic rate (FSR) were calculated during a 16-h primed constant infusion of L-[ring-2H5]phenylalanine. Ingestion of a combination of CAA supplements and meals resulted in a greater mixed muscle FSR than ingestion of the meals alone (SUP, 0.099 +/- 0.008; CON, 0.076 +/- 0.005%/h; P < 0.05). Both groups experienced an improvement in NB after the morning (SUP, -2.2 +/- 3.3; CON, -1.5 +/- 3.5 nmol x min(-1) x 100 ml leg volume(-1)) and evening meals (SUP, -9.7 +/- 4.3; CON, -6.7 +/- 4.1 nmol x min(-1) x 100 ml leg volume(-1)). NB after CAA ingestion was significantly greater than after the meals, with values of 40.2 +/- 8.5 nmol x min(-1) x 100 ml leg volume(-1). These data indicate that CAA supplementation produces a greater anabolic effect than ingestion of intact protein but does not interfere with the normal metabolic response to a meal.     

Selective antagonism of peptidoleukotriene responses does not reduce myocardial damage or neutrophil accumulation following coronary artery occlusion with reperfusion

This study was designed to assess the effect of a peptidoleukotriene receptor antagonist, SK&F 104353, for limiting myocardial damage and neutrophil accumulation in rats subjected to myocardial reperfusion injury (MI/R). In conscious rats, SK&F 10,4353 (25 mg/kg, i.v.) antagonized LTD4-induced vasopressor responses by 90% and 60% at 1 and 4 hr, respectively, indicating effective blockade of peptido-leukotriene responses. In another group of animals subjected to 30 min of coronary artery occlusion with reperfusion for 24 hr, myocardial injury and neutrophil infiltration were determined by measuring creatine phosphokinase (CPK) specific activity and myeloperoxidase (MPO) activity, respectively, in the left ventricular free wall (LVFW). Myocardial CPK levels were 8.1 +/- 0.2 U/mg protein in Sham-MI/R vehicle-treated animals, and were significantly decreased to 6.4 +/- 0.6 U/mg protein in MI/R-vehicle animals. Myocardial MPO values were 1.5 +/- 0.5 U/g LVFW in Sham-MI/R vehicle-treated animals, and significantly increased to 4.3 +/- 0.6 U/g LVFW in MI/R-vehicle animals. Administration of SK&F 10,4353 (25 mg/kg, i.v.) 1 min prior to coronary occlusion and 3.5 hr post reperfusion had no effect on the loss of myocardial CPK specific activity or the increase in MPO levels (p greater than 0.05, compared to the MI/R-vehicle group). Thus, at a dose that antagonized LTD4-induced vasopressor responses, SK&F 104353 did not attenuate either the extent of myocardial injury or inflammatory cell accumulation associated with myocardial ischemia/reperfusion. These results suggest that peptidoleukotrienes do not contribute to the progression of myocardial ischemic/reperfusion injury.     

DNA damage of tumor-associated lymphocytes and total antioxidant capacity in cancerous patients

The purpose of this study was to assess DNA damage of tumor-associated lymphocytes (TALs) in malignant pleural effusion (MPE), the total antioxidant capacity (TAC) of plasma and MPE from patients with carcinoma, and DNA repair effect of melatonin. TAC of plasma was measured in 28 cancer patients with MPE and in 33 healthy persons, and also TAC of MPE supernatant was measured in these patients. DNA damages of peripheral blood mononuclear cells (PBMCs) and of TALs were assessed using comet assay. The TAC of plasma was remarkably lower in cancer patients (8.41+/-1.78 U/ml) than that in healthy persons (10.52+/-1.64 U/ml, P<0.001). The TAC of MPE supernatant (6.34+/-1.57 U/ml) was significantly lower than that of plasma in cancer patients (8.41+/-1.78 U/ml, P<0.001). The comet percentage of PBMCs was higher in cancer patients (16.8+/-7.9) than that in healthy persons (10.4+/-4.9, P<0.01). Within cancer patients, the comet percentage of TALs (41.9+/-11.7) was significantly higher than that of PBMCs (16.8+/-7.9, P<0.001). A negative correlation was observed between the TAC of MPE supernatant and the comet percentage of TALs in patients (r=-0.538, P<0.01). After treatment with melatonin, comet percentage of TALs declined significantly from 42.6+/-12.8 to 27.1+/-9.9 (P<0.001). These data show that lower TAC of MPE supernatant may be related to higher degree of DNA damage of TALs and that melatonin may facilitate the repair of the damaged DNA.     

The effects of isokinetic contraction velocity on concentric and eccentric strength of the biceps brachii

The purpose of this investigation was to determine the influence of contraction velocity on the eccentric (ECC) and concentric (CON) torque production of the biceps brachii. After performing warm-up procedures, each male subject (n = 11) completed 3 sets of 5 maximal bilateral CON and ECC isokinetic contractions of the biceps at speeds of 90, 180, and 300 degrees x s(-1) on a Biodex System 3 dynamometer. The men received a 3-minute rest between sets and the order of exercises was randomized. Peak torque (Nm) values were obtained for CON and ECC contractions at each speed. Peak torque scores (ECC vs. CON) were compared using a t-test at each speed. A repeated measures analysis of variance was used to determine differences between speeds. ECC peak torque scores were greater than CON peak torque scores at each given speed: 90 degrees x s(-1), p = 0.0001; 180 degrees x s(-1), p = 0.0001; and 300 degrees x s(-1), p = 0.0001. No differences were found between the ECC peak torque scores (p = 0.62) at any of the speeds. Differences were found among the CON scores (p = 0.004). Post hoc analysis revealed differences between 90 degrees x s(-1) (114.61 +/- 23) and 300 degrees x s(-1) (94.17 +/- 18). These data suggest that ECC contractions of the biceps brachii were somewhat resistant to a force decrement as the result of an increase in velocity, whereas CON muscular actions of the biceps brachii were unable to maintain force as velocity increased.     

Prophylactic effects of magnesium and vitamin E in rat spinal cord radiation damage: evaluation based on lipid peroxidation levels

This study investigated the neuroprotective effects of magnesium sulfate prophylaxis and vitamin E prophylaxis in a rat model of spinal cord radiation injury. Groups were subjected to different treatment conditions for 5 days prior to irradiation, and outcomes were evaluated on the basis of lipid peroxidation levels in cord tissue. Four groups of rats were investigated: no radiation/treatment (n = 4), intraperitoneal (i.p.) saline 1 ml/day (n = 6), i.p. vitamin E 100 mg/kg/day (n = 6), and i.p. magnesium sulfate 600 mg/kg/day (n = 6). The thoracic cord of each non-control rat was exposed to 20 Gy radiation in a LINAC system using 6 MV x-rays, and malondialdehyde (MDA) levels (reflecting lipid peroxidation level) were determined 24 hours post-irradiation. The MDA levels in thoracic cord segments from the control rats were used to determine baseline lipid peroxidation. The mean levels in the control, saline-only, vitamin E, and magnesium sulfate groups were 12.12 +/- 0.63, 27.0 +/- 2.81, 17.71 +/- 0.44, and 14.40 +/- 0.47 nmol/mg tissue, respectively. The MDA levels in the saline-only group were significantly higher than baseline, and the levels in the vitamin E group were significantly lower than those in the saline group (P < 0.05 for both). The levels in the magnesium sulfate group were dramatically lower than those in the saline group (P < 0.001). The results indicate that i.p. magnesium sulfate has a marked neuroprotective effect against radiation-induced oxidative stress in the rat spinal cord.     

Phalloidin attenuates postischemic neutrophil infiltration and increased microvascular permeability.

The aim of this study was to determine whether phalloidin (1 microM) or antamanide (1 microM), cyclic peptides that stabilize dense peripheral band and stress fiber F-actin in endothelium, would attenuate the increase in microvascular permeability induced by 4 h of ischemia and 30 min of reperfusion (I/R) in the isolated canine gracilis muscle. Changes in microvascular permeability (1 - sigma) were assessed by determining the solvent drag reflection coefficient for total plasma proteins (sigma) in muscles subjected to 4.5 h of continuous perfusion (nonischemic controls), I/R alone, I/R + phalloidin, or I/R + antamanide. Muscle neutrophil content was assessed by determination of myeloperoxidase (MPO) activity in tissue samples obtained at the end of the experiments. Fluorescent detection of nitrobenzoxadiazole-phallicidin in endothelial cell monolayers confirmed that phalloidin enters these cells. I/R was associated with marked increases in microvascular permeability and muscle neutrophil content (1 - sigma = 0.45 +/- 0.07; MPO = 8.9 +/- 0.5 units/g) relative to control (4.5 h continuous perfusion) preparations (1 - sigma = 0.12 +/- 0.03; MPO = 0.5 +/- 0.8 unit/g). These I/R-induced changes were largely prevented by administration of phalloidin (1 - sigma = 0.19 +/- 0.02; MPO = 0.8 +/- 0.4 U/g) or antamanide (1 - sigma = 0.07 +/- 0.11; MPO = 0.9 +/- 0.3 unit/g) at reperfusion. Similar results were obtained when phalloidin was administered before ischemia (1 - sigma = 0.24 +/- 0.04; MPO = 1.2 +/- 1.0 units/g). Although antamanide decreased superoxide production (by approximately 60%) and adherence to plastic (by approximately 75%) by activated neutrophils in vitro, phalloidin failed to alter these aspects of granulocyte function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum levels of TNF-alpha,sIL-2R,IL-6, and IL-8 are increased and associated with elevated lipid peroxidation in patients with Behçet's disease

AIM: Behçet''s disease (BD) is asystemic immunoinflammatory disorder and the aetiopathogenesis is to be specified. Cytokines play a role in immune response and in many inflammatory diseases. The aim of this case-control study is to investigate serum pro-inflammatory cytokine tumour necrosis factor (TNF)-alpha, interleukin-1beta (IL-1beta), soluble IL-2 receptor (sIL-2R), IL-6, and chemokine IL-8 levels in patients with BD. We also determined the end product of lipid peroxidation (malondialdehyde (MDA)) in BD patients as an index for oxidative stress. METHODS: A total of 37 patients (19 men, 18 women) with BD (active, n = 17; inactive, n = 20) and 20 age-matched and sex-matched healthy control subjects (11 men, nine women) included in this cross-sectional, blinded study. Serum TNF-alpha, IL-1beta, sIL-2R, IL-6 and IL-8 levels were determined by a spectrophotometer technique using the immulite chemiluminescent immunometric assay. Lipid peroxidation was evaluated by Wasowicz et aL The levels of cytokines and lipid peroxidation in the active period were compared with the inactive period of the disease. Results are expressed as mean +/- standard error. RESULTS: IL-1beta levels were below the detection limits of the assay (< 5 pg/ml) in all samples. Mean levels of MDA (8.1+/-0.7 micromol/l), sIL-2R (800+/-38 U/ml), IL-6 (12.6+/-1.1 pg/ml), IL-8 (7.2+/-0.4 pg/ml), and TNF-alpha (7.9+/-0.5 pg/ml) in active BD patients were significantly higher than those in inactive patients (4.3+/-0.5 micromol/l, p < 0.01; 447+/-16 U/ml, p < 0.001; 8.3+/-0.6 pg/ml, p = 0.006; 5.3+/-0.1 pg/ml, p < 0.001; and 5.1 0.2 pg/ml, p < 0.001; respectively) or control subjects (2.1+/-0.2 micromol/l, p < 0.001; 446+/-20 U/ml, p < 0.001; 6.4+/-0.2 pg/ml, p < 0.001; 5.4+/-0.1 pg/ml, p < 0.001; and 4.7+/-0.1 pg/ml, p < 0.001, respectively). On the contrary, only the mean IL-6 level was significantly different between inactive BD and control subjects (p = 0.02). All acute phase reactants were significantly higher in active BD than in inactive period (for each, p < 0.01). Conclusions: High levels of sIL-2R, IL-6, IL-8 and TNF-alpha indicate the activation of immune system in BD. Serum sIL-2R, IL-6, IL-8 and TNF-alpha seem to be related to disease activity. Increased lipid peroxidation suggests oxidative stress in BD and therefore tissue damage in such patients. Amelioration of clinical manifestations would be envisaged by targeting these cytokines, chemokines and lipid peroxidation with pharmacological agents.