Free Amino-nitrogen Compounds Research Articles

Physicochemical Properties and Malting Potential of New Canadian Hulless Barley Genotypes

Interest in malting hulless barley (HB) is driven by its potential to produce very high levels of malt extract, but elevated levels of wort ß-glucan and insufficient levels of enzymes in hulless malt have prevented its widespread use. The objective of this study was to highlight the recent advancements in quality improvement of Canadian HB for malting purposes. Five advanced HB lines were evaluated for various barley and malt quality characteristics. All hulless lines exhibited lower grain hardness and slightly lower kernel weight and diameter compared to AAC Synergy (a popular two-rowed covered Canadian variety). The average total starch content of the hulless barley lines (64.2%) was significantly higher than AAC Synergy (59.9%) but slightly lower than that of CDC Clear (65.1%). Despite the low friability values, HB malts had a crumbly texture with good solubility and enzyme accessibility resulting in ample production of fermentable sugars. The average chain length of starch hydrolysis products in wort of new HB lines was similar to that of AAC Synergy, indicating sufficient enzyme activities and a highly effective hydrolysis. The fine-grind extract levels from hulless malt were on average 8% higher than from AAC Synergy, and several new HB lines exceeded the level of CDC Clear extract by 0.7–1.0%. Compared to CDC Clear, the new HB lines showed a significant reduction in concentration of wort ß-glucans. The concentration and the average degree of polymerization of arabinoxylo-oligosaccharides in wort of HB lines were generally higher than in wort of AAC Synergy, partly explaining the higher viscosity of HB worts. In general, the recently developed HB lines exhibited excellent malting potential with significant improvements in the levels of malt enzymes, concentration of free amino nitrogen compounds, and β-glucans in wort.

Application of Water Treated with Low-Temperature Low-Pressure Glow Plasma for Quality Improvement of Barley and Malt.

The aim of this study is to determine the quality of water treated with low-temperature, low-pressure glow plasma, either in the air or under nitrogen, in order to obtain high-quality brewer’s malt. To this end, plasma-treated spring water was used for barley grain soaking. In two-row spring barley grain, the procedure provided significantly higher water uptake capacity and grain sensitivity to water, as well as energy and germination capacity. The resulting malt showed improved moisture and 1000-grain mass. Furthermore, laboratory wort produced from the malt by the congress method did not differ statistically from a control sample in terms of filtration time, pH, turbidity, color, extract, free amino nitrogen compounds, and aromatic composition.

Ethanol Production from Extruded Thermoplastic Maize Meal by High Gravity Fermentation with Zymomonas mobilis

A comparative study of extruded and ground maize meals as raw materials for the production of regular (12°P) and high gravity (20°P) worts was devised. Extruded water solubility index (WSI) was higher (9.8 percentage units) and crude fat was lower (2.64 percentage units) compared to ground maize. Free-amino nitrogen compounds (FAN), pH, and glucose were evaluated in regular and high gravity worts produced from ground or extruded maize. Extrusion improved glucose content and ethanol yield. In 20°P mashes, extrusion is enhanced by 2.14% initial glucose compared with regular ground mashes. The 12°P and 20°P extruded treatments averaged 12.2% and 8.4% higher ethanol, respectively, compared to the uncooked counterpart. The 20°P worts fermented with Zymomonas mobilis produced 9.56% more ethanol than the 12°P counterpart. The results show that the combination of extrusion and fermentation of 20°P worts improved ethanol yield per kg flour until 20.93%. This pretreatment stimulates Z. mobilis fermentation efficiency.

Effect of nitrogen nutrition on amino acid composition of xylem sap and stem wood in Alnus glutinosa

Citrulline was the major amino acid in root pressure sap, stem sap and stem wood from Alnus glutinosa L. Gaertn. plants relying on fixed nitrogen or, partly or wholly, on mineral nitrogen for growth. Glutamine increased in prominence in plants assimilating mineral nitrogen but asparagine remained a relatively insignificant component. Differences in the relative amounts of the free amino compounds of stem sap from nitrogen‐fixing and mineral nitrogen‐fed plants were usually small compared to differences between plants fed different sources of mineral nitrogen. In contrast, relatively high values for the ratios of citrulline/total free amino nitrogen compounds and particularly of citrulline/amides in root pressure sap distinguished nitrogen‐fixing plants from those receiving mineral nitrogen. Although the amino acid ratios of stem wood extracts showed closer similarity to those for root pressure sap than stem sap, the seasonal accumulation of citrulline, possibly as a storage amino acid, in stem wood from field‐grown plants negated the possibility of utilising stem wood analyses as an indicator of the form of nitrogen assimilation. Comparative data on the levels of citrulline or other free amino acids in Alnus glutinosa are unlikely to be useful as an index of nitrogen fixation, under most experimental conditions.

Protective Effects of a Novel Nonglucocorticoid 21-Aminosteroid (U74006F) During Traumatic Shock in Rats

The purpose of this study was to investigate the effect of the nonglucocorticoid steroid U74006F in the pathogenesis of a murine traumatic shock model. Pentobarbital-anesthetized (40 mg/kg) rats were subjected to Noble-Collip drum trauma and developed a lethal shock state characterized by a decreased mean arterial blood pressure (MABP) to 67 +/- 2 mm Hg and survival time (1.5 +/- 0.2 h). In contrast, sham trauma rats exhibited a MABP of 122 +/- 4 mm Hg at 5 h postanesthesia. Administration of U74006F at doses of 22.5 mg/kg at 15 to 20 min following trauma significantly maintained a higher MABP and prolonged survival compared to those trauma rats receiving only the vehicle for U74006F (0.002 N HCl). U74006F at 15 and 22.5 mg/kg prolonged survival time to 2.6 +/- 0.3 (p less than 0.05) and 3.1 +/- 0.6 h (p less than 0.02), respectively. U74006F also significantly attenuated the plasma accumulation of cathepsin D (p less than 0.02 to p less than 0.01) and free amino-nitrogen compounds (p less than 0.01) compared to the rats receiving only vehicle. Additionally, U74006F at 15 and 22.5 mg/kg blunted the production of the cardiotoxic peptide, myocardial depressant factor (MDF) (p less than 0.01 to p less than 0.001). Moreover, U74006F is a steroid without significant glucocorticoid or mineralocorticoid activity. These results suggest that U74006F may be useful as a therapeutic agent in traumatic shock.

Acute effects of unsaturated fatty acids in splanchnic artery occlusion shock

Diets enriched with omega-3 unsaturated fatty acids are associated with decreased hypercholesterolemia and decreased risk of ischemic and atherosclerotic diseases. We studied the acute intravascular effects of some of these unsaturated fatty acids (i.e., eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) along with omega-6 unsaturated fatty acids, (i.e., linoleic and linolenic acid) in splanchnic artery occlusion (SAO) shock in rats. Anesthetized rats subjected to total occlusion of the celiac and superior mesenteric arteries for 40 minutes followed by reperfusion usually resulted in a fatal outcome 90–120 minutes after releasing the clamps. SAO shock rats treated with the omega-3 unsaturated fatty acid, EPA, exhibited an improved survival time and rate (p<0.05 from vehicle) compared to those receiving only vehicle (i.e., 50% ethanol). EPA and DHA treated SAO rats also exhibited lower plasma activities of the lysosomal protease, cathepsin D, free amino-nitrogen compounds, and the cardiotoxic peptide, myocardial depressant factor. These results indicate that omega-3 unsaturated fatty acids, especially EPA, have some acute beneficial effects in SAO shock in rats.

Protective effects of a specific platelet activating factor (PAF) antagonist, WEB 2086, in traumatic shock

We have investigated the role of platelet activating factor (PAF) in the pathogenesis of a murine model of traumatic shock using WEB 2086, a specific antagonist of PAF. WEB 2086 (0.5 mg/kg) significantly reversed the decrease in mean arterial blood pressure (MABP) induced by PAF (0.3 μg/kg) in anesthetized rats. Anesthetized rats were subjected to Noble-Collip drum trauma. Traumatized rats treated with WEB 2086 (0.5 mg/kg bolus followed by infusion at 0.5 mg/kg/hr) maintained a higher MABP than those receiving only the vehicle (0.9% NaCI). Improvement in MABP paralleled a significant increase in overall survival time (p<0.01) in rats receiving WEB 2086 (0.5 mg/kg). WEB 2086 also significantly attenuated the plasma accumulation of the lysosomal hydrolase, cathepsin D and of free amino-nitrogen compounds, compared to shocked rats receiving only the vehicle. Furthermore, the production of the cardiotoxic peptide, myocardial depressant factor (MDF) was also blunted by WEB 2086. These results suggest that PAF may be an important mediator in the pathogenesis of traumatic shock in rats. Furthermore, PAF receptor antagonists may be useful as therapeutic agents when given early in the course of ischemic and shock states.

Salutary Effects of CG-4203, a Novel, Stable Prostacyclin Analog, in Hemorrhagic Shock

Prostacyclin (PGI2) is a potent vasodilator, an inhibitor of platelet aggregation, and a membrane-stabilizing agent that has been shown to exert beneficial effects in a variety of models of ischemia and circulatory shock. However, the use of PGI2 is limited by its instability and rapid biodegradation. We studied the effects of a novel, stable prostacyclin analog, CG-4203, in a murine model of hemorrhagic shock. Hemorrhaged rats treated with CG-4203 maintained postreinfusion mean arterial blood pressure (MABP) at significantly higher values than rats receiving only the vehicle (final MABP 101 +/- 3 vs. 75 +/- 5 mm Hg, p less than 0.01). CG-4203 was also found to attenuate the increase in plasma cathepsin D activity (p less than 0.01), as well as the plasma accumulation of free amino-nitrogen compounds (p less than 0.05). Furthermore, the plasma activity of a myocardial depressant factor (MDF) was significantly lower in CG-4203-treated hemorrhaged rats than in rats receiving the vehicle (25 +/- 2 vs. 54 +/- 7 U/ml, p less than 0.01). In addition, CG-4203 exerted an anti-proteolytic action in pancreatic homogenates and inhibited platelet aggregation in platelet-rich plasma. However, CG-4203, at concentrations expected during treatment of shock, failed to have an immediate or delayed vasodilator effect in rat aortic rings, and thus vasodilation is not an important aspect of the antishock effects of CG-4203. Our results suggest that inhibition of platelet aggregation, as well as the antiproteolytic and membrane-stabilizing actions, could mediate the beneficial effects of CG-4203 in hemorrhagic shock.

Anti-shock effects of human superoxide dismutase in splanchnic artery occlusion (SAO) shock.

We studied the effects of human superoxide dismutase (h-SOD) in splanchnic artery occlusion (SAO) shock. Pentobarbital anesthetized rats subjected to total occlusion of the superior mesenteric and the celiac arteries for 40 min developed a severe shock state usually resulting in a fatal outcome within 20 min after the release of the occlusion. h-SOD (10 mg/kg) was infused intravenously starting at reperfusion and lasting for 10 min. SAO shock rats treated with h-SOD maintained postreperfusion MABP at significantly higher values compared to rats receiving the vehicle (final MABP 84 +/- 6 vs 46 +/- 1 mm Hg, P less than 0.01, respectively). Treatment with h-SOD attenuated the plasma accumulation of free amino-nitrogen compounds (P less than 0.01 from vehicle) as well as the activity of the lysosomal protease cathepsin D (P less than 0.05 from vehicle). Furthermore, the plasma activity of a myocardial depressant factor was significantly lower in h-SOD-treated rats than in SAO rats receiving only the vehicle (27 +/- 1 vs 64 +/- 3 U/ml, P less than 0.01). SAO shock rats treated with h-SOD also exhibited a significantly higher survival rate than the SAO shock +/- vehicle group (88% vs 11%, P less than 0.01, respectively). These results support the role of oxygen-derived radicals in the pathophysiology of SAO shock, and indicate that h-SOD effectively ameliorates the deleterious effects of oxygen radicals in this severe model of ischemia and reperfusion.

Use of a novel peptide leukotriene receptor antagonist, Ly-163443, in splanchnic artery occlusion shock

We studied the effects of LY-163443, a novel selective receptor antagonist of LTD 4 and LTE 4, in splanchic artery occlusion (SAO) shock. LY-163443 antagonized the bronchoconstrictor effect of LTD 4 given intravenously to anesthetized rats. Anesthetized rats subjected to total occlusion of the superior mesenteric and the celiac arteries for 40 minutes developed a severe shock state usually resulting in a fatal outcome within two hours after release of the occlusion. SAO shock rats pre-treated with LY-163443 before the occlusion of the splanchnic arteries maintained post-release MABP at significantly higher values compared to rats reveiving either the vehicle or LY-163443 as a post-treatment 15 min after occlusion (final MABP 96 ± 8 vs 51 ± 1, p < 0.01 and 53 ± 3, p < 0.01, respectively). Pre-treatment with LY-163443 attenuated the release of the lysosomal hydrolase, cathepsin D (p < 0.01 from vehicle and p < 0.05 from post-treatment groups), and the plasma accumulation of free amino-nitrogen compounds (p < 0.05 from vehicle). Furthermore, the plasma activity of a myocardial depressant factor (MDF) was significantly lower in the pre-treatment group than in the vehicle group (27 ± 3 vs 51 ± 6 U/ml, p < 0.01). SAO shock rats pretreated with LY-163443 also exhibited significantly higher survival rates (p < 0.01 from vehicle and post-treatment groups), and prolonged survival times (p < 0.01 from vehicle and post-treatment groups). The beneficial effects of the leukotriene receptor antagonist LY-163443 support the concept that peptide leukotrienes act as mediators of the pathogenesis of SAO shock.

Salutary consequences of blockade of platelet activating factor in hemorrhagic shock

We studied the effects of a potent, specific platelet activating factor (PAF) antagonist, CV-6209, in a murine model of hemorrhagic shock. Hemorrhaged rats treated with CV-6209 (1 mg/kg) maintained post-reinfusion mean arterial blood pressure (MABP) at significantly higher values than rats receiving either 0.9% NaCl or a lower dose (0.2 mg/kg) of CV-6209 (final MABP 88 ± 4 vs. 57 ± 4, vs. 61 ± 7 mm Hg, respectively). CV-6209 (1 mg/kg) also significantly attenuated the increase in plasma cathepsin D activity following hemorrhage compared with hemorrhaged rats receiving only its vehicle (i.e. 0.9% NaCl). CV-6209 (1 mg/kg) also significantly decreased the plasma accumulation of free amino-nitrogen compounds and the plasma activity of a myocardial depressant factor (MDF) compared to hemorrhaged rats receiving 0.9% NaCl. Rats receiving CV-6209 (1 mg/kg) exhibited a significantly increased survival rate and survival time post-reinfusion compared to rats receiving only the vehicle. These data indicate that PAF is an important mediator of hemorrhagic shock in the rat and that PAF receptor antagonists may be useful in hemorrhagic shock states.

Mechanisms of action of PGE1 in hemorrhagic shock in rats.

We studied the effects of prostaglandin E1 (PGE1) in a severe model of hemorrhagic shock in rats. PGE1 was administered as a continuous IV infusion of either 0.1 microgram/kg/min or 1.0 microgram/kg/min starting 30 minutes after the onset of bleeding and continuing until one hour after reinfusion. Hemorrhaged rats treated with PGE1 (1 microgram/kg/min) maintained post-reinfusion mean arterial blood pressure (MABP) at significantly higher values than rats receiving only the vehicle (ie, 0.9% NaCl) (final MABP 84 +/- 3 vs 57 +/- 4 mm Hg, P less than .01). PGE1 at 1 microgram/kg/min also attenuated the increase in plasma activities of cathepsin D (P less than .01), and at both doses blunted the plasma accumulation of free amino-nitrogen compounds (P less than .02 at 0.1 microgram/kg/min and P less than .01 at 1.0 microgram/kg/min). Furthermore, the plasma activity of a myocardial depressant factor (MDF) was significantly lower in rats treated with PGE1 (1 microgram/kg/min) than in rats receiving the vehicle (35 +/- 4 U/mL vs 74 +/- 12 U/mL, P less than .01). Rats receiving PGE1 (1.0 microgram/kg/min) also exhibited a significantly increased survival rate (P less than .01) and post-reinfusion survival time (P less than .01) compared with rats receiving only the vehicle. Our data suggest that antiproteolytic and membrane-stabilizing actions of PGE1 are important and may contribute to its beneficial effects in hemorrhagic shock. Other mechanisms (eg, inhibition of platelet aggregation and vasodilation) may also be involved.