Protease supplementation attenuates the intestinal health damage caused by low-protein diets in Pekin ducks.

The objective of this study was to investigate the effects of low-protein diets with low digestibility of feed ingredients on intestinal damage and to explore whether the protease supplementation can alleviate the damage in Pekin ducks. A total of 576 Pekin ducklings (6 replicate pens, 16 ducks/pen) were randomly assigned to 6 dietary treatments (3 × 2 factorial arrangement) in a randomized complete block design. Factors were CP levels (13.5%, 15.5%, and 17.5%) and protease (0 or 20,000U/kg). Compared with the diets containing 17.5% CP, low-protein diets (13.5% CP) showed suppressed (P < 0.05) growth performance and feed intake (FI); reduced (P < 0.05) serum-free arginine, isoleucine, leucine, methionine, phenylalanine, valine, and proline as well as the cecal acetate and propionate concentration; increased (P < 0.05) plasma and ileal mucosal tumor necrosis factor-α (TNF-α) concentration; and downregulated (P < 0.05) mRNA expression of TNF-α, nuclear transcription factor-κb, interferon gamma, and Occludin in ileal mucosa. Irrespective of the dietary CP levels, protease supplementation significantly increased (P < 0.05) the serum-free glutamic acid concentration while decreasing (P < 0.05) the plasma endotoxin, IL-6, and the cecal isovalerate concentration. A significant interactive effect was observed between low-protein diets and protease supplementation (P < 0.05) on serum-free arginine concentration, the ratio of ileal villus height to crypt depth, and the IL-6 concentration in ileal mucosa. These results indicated that low-protein diets could damage intestinal integrity to induce systemic inflammation response and at last to suppress growth performance. Protease supplementation could partly attenuate the negative effects on gut health caused by low-protein diets in Pekin ducks.

Effects of dietary protein levels and protease supplementation on growth performance, carcass traits, meat quality, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet.

This study aimed to investigate to the effects of dietary CP levels and protease supplementation on growth performance, carcass traits, meat quality, nutrients utilization, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet. A total of 960 14-day-old male ducks were weighed and randomly allotted to a 2 × 5 factorial arrangement of 10 treatments with 6 replicate pens per treatment and 16 ducks per pen fed to 49 D of age. Experimental factors included five dietary CP levels ranging from 13.5 to 17.5% and with or without protease (200 mg/kg) supplementation. Between day 28 to 34, the digestible and metabolizable trials were performed. Significant CP × protease interactions (P < 0.05) on breast meat yield, DM, energy and nitrogen utilization, as well as standardized ileal digestibility values of 7 amino acids were observed. Regardless of protease supplementation, ducks fed 13.5, 14.5, and 15.5% CP had a poorer (P < 0.05) growth performance and breast meat yield than ducks fed with 16.5 and 17.5% CP. Ducks fed 13.5% CP had a positive effect (P < 0.05) on meat quality, dietary DM, energy and nitrogen utilization as well as standardized ileal digestibility of amino acids. Protease supplementation increased (P < 0.05) DM and phosphorus retention and decreased (P < 0.05) shear force of breast meat, regardless of CP level; when CP = 14.5%, protease significantly increased (P < 0.05) breast muscle yield. The optimal CP requirement without or with protease supplementation for BWG and FI were 17.02 or 16.53% and 16.64 or 16.75%, respectively, based on linear broken-line regression.

Cyclic fluctuations in the cardiac performance of the isolated Langendorff-perfused mouse heart: pyruvate abolishes the fluctuations and has an anti-ischaemic effect.

During the development of a Langendorff preparation of isolated mouse hearts, hitherto undescribed cyclic fluctuations in left ventricular pressure and coronary flow were independently observed in three laboratories. Isolated mouse hearts were perfused with crystalloid glucose-containing Krebs-Hensleit buffer in a constant pressure model, and left ventricular pressures were measured via an intraventricular balloon catheter. After acquiring technical skill in preparing the mouse hearts, the perfusionists observed that fluctuations in cardiac performance with a cycle period lasting 5-10 min occurred shortly after initiation of perfusion. Each fluctuation cycle consisted of a phase of increase and a phase of decrease. Synchronized with the fluctuations in left ventricular pressure, increases and decreases in dP/dt max took place. Analogous fluctuations in coronary flow occurred, with onset 1-2 min later than changes in left ventricular systolic pressure. In some preparations a gradual ST-segment elevation was seen on the electrocardiogram during the systolic pressure increase phase. The amplitude of the fluctuations could be augmented by increasing the perfusion pressure, and reduced, but not abolished, by lowering the pressure. Changes in buffer calcium, magnesium, or sodium concentration did not alter the fluctuations, nor did any change of anaesthetics, mouse strain, or left ventricular drainage. Altering the perfusion mode from constant pressure to constant flow did not prevent the occurrence of the cyclic fluctuations. The hearts became stable and the fluctuations disappeared when the buffer was supplemented with 2 mm pyruvate. In the present study, pyruvate given throughout stabilization and reperfusion also markedly attenuated the ischaemic insult, as evidenced by the delayed ischaemic contracture and a reduced magnitude of ischaemic contracture. A cardioprotective effect was only visible at early reperfusion, did not affect the final functional recovery. In conclusion, a phenomenon of cyclic fluctuations in left ventricular pressure followed by fluctuations in coronary flow was observed in isolated mouse hearts. These could be abolished by adding 2 mm pyruvate to the perfusion buffer. Pyruvate in the buffer also markedly attenuated the post-ischaemic deterioration of cardiac performance seen in this mouse model.

Sensitization of human colon cancer cells to TRAIL-mediated apoptosis.

TNF-related apoptosis-inducing ligand (TRAIL), a novel member of the tumor necrosis factor (TNF) family, is thought to induce apoptosis preferentially in cancer cells; however, increasing evidence suggests that a number of cancers are resistant to TRAIL treatment. FLICE-like inhibitory protein (FLIP), which structurally resembles caspase-8, can act as an inhibitor of apoptosis when expressed at high levels in certain cancer cells. The purpose of our present study was to determine whether human colon cancer cells are sensitive to TRAIL treatment and, if not, to identify potential mechanisms of resistance. Colon cancer cells of different metastatic potential (KM12C, KML4A, and KM20) were found to be resistant to the effects of TRAIL when used as a single agent. FLIP expression levels were increased in all three KM cell lines. Treatment with either actinomycin D (Act D;10 :g/ml) or cycloheximide (CHX; 10 :g/ml) decreased FLIP expression levels in all three cell lines. The decrease in cellular levels of FLIP was associated with sensitization to TRAIL-mediated apoptosis, as demonstrated by enhanced cell death and caspase-3 activity compared with either Act D or CHX alone. Our findings suggest that reduction of FLIP levels by Act D or CHX renders TRAIL-resistant human colon cancer cells sensitive to TRAIL-mediated apoptosis. The combination of TRAIL along with agents such as Act D or CHX, which target proteins that prevent cell death, may provide a more effective and less toxic regimen for treatment of resistant colon cancers.

The lipid peroxidation inhibitor indenoindole H290/51 protects myocardium at risk of injury induced by ischemia-reperfusion.

Lipid peroxidation contributes to myocardial reperfusion injury. The indenoindole H290/51, a lipid peroxidation inhibitor with balanced lipophilicity and a considerably higher antioxidative capacity than that of vitamin E, was tested for its myocardioprotective effect against reperfusion injury. Coronary-ligated pigs were subjected to 45 min of myocardial ischemia followed by 240 min of reperfusion. Starting five minutes prior to reperfusion, H290/51 (n = 6) or vehicle (n = 6) was retrogradely infused via a coronary vein for 30 min. The total dose of H290/51 was 1 microM in 300 ml fluid (10 ml/min). In addition to the hemodynamics, left ventricular (LV) wall segment shortening (%SS) was measured by sonomicrometry. The LV area at risk and infarct size were measured by means of Evans blue and triphenyl tetrazolium chloride staining. The hemodynamics did not change significantly during the study, and no differences were found between the two groups. In the H 290/51-treated pigs, %SS of the ischemic area recovered from 1.9% at the end of ischemia to 9.1% after 120 min (p < .05) and to 16.2% at 240 min (p < .01). There was no significant recovery in the vehicle group. The LV area at risk was approximately 20% of LV. Infarct size as a percentage of LV and of the area at risk was significantly smaller in the H290/51 group (9+/-3% and 46+/-11%) than in the control group (18+/-6%; p < .05 and 83+/-5%; p < .01). H290/51 effectively protected the myocardium at risk in the setting of myocardial ischemia followed by reperfusion. This effect was reflected by diminished infarct size and improved functional recovery.

Effect of Astragulas membranaceus on natural killer cell activity and induction of alpha- and gamma-interferon in patients with Coxsackie B viral myocarditis.

The patients suffering from Coxsackie B viral myocarditis with depressed natural killer (NK) activity were treated with Astragulas membranaceus (AM) intramuscularly for 3-4 months. After the treatment, the NK activity was increased significantly from 11.5 +/- 11.9% before therapy to 44.9 +/- 15.0%. Another 6 patients of Coxsackie B viral myocarditis with depressed NK activity were treated with conventional therapy. The NK activity remained unchanged in 12.9 +/- 6%. The general condition and symptoms improved in all patients with AM therapy, while the titers of neutralizing antibody remained at the same level. Two days after AM treatment, the mean titers of alpha- and gamma-interferon (IFN) markedly increased in comparison with those before therapy and 3 weeks after AM therapy in 16 patients with Coxsackie B viral myocarditis, with left ventricular ejection fraction (LVEF) less than 65% and/or weak ventricular wall motion assayed by radionuclide angiocardiography. Whereas, in 12 patients treated with conventional therapy, there was no statistical difference among the results before and 2 days and 3 weeks after treatment. The results indicate that AM could partly regulate the lost of control of cellular immunity in patients with viral myocarditis.