Initial Rate Of Production Research Articles

Olive oil mill effluents as a feedstock for production of biodegradable polymers

The aim of the present paper was to study the feasibility of using olive oil mill effluents (OMEs) as a substrate in biodegradable polymer production. OMEs were anaerobically fermented to obtain volatile fatty acids (VFAs), which are the most highly used substrate for polyhydroxyalkanotes (PHAs) production. The anaerobic fermentation step was studied both without pretreatment and with different pretreatments (i.e., centrifugation, bentonite addition, and bentonite addition followed by centrifugation) and at various concentrations (28.5, 36.7 and 70.4 g COD L −1). During fermentation, VFA concentration was determined (7–16 g COD L −1) as well as the corresponding yield with respect to initial COD (22–44%). At all initial concentrations, centrifugation pretreatment (with or without previous addition of bentonite) significantly increased the final VFA concentration and yield, whereas the addition of bentonite alone had no influence. Moreover, centrifugation pretreatment led to a different acid distribution, which affected the hydroxyvalerate (HV) content within the obtained copolymer poly β-(hydroxybutyrate-hydroxyvalerate) [P(HB-HV)]. OMEs were tested for PHA production by using a mixed culture from an aerobic SBR. Centrifuged OMEs, both with or without fermentation, were tested. PHAs were produced from both matrices, but with fermented OMEs PHA production was much higher, because of the higher VFA concentration. The initial specific rate of PHA production obtained with fermented OMEs was approximately 420 mg COD g COD −1 h −1 and the maximum HV content within the copolymer was about 11% (on a molar basis). The HV monomer was produced only until propionic acid remained present in the medium.

Effect of germination temperature on characteristics of phytase production from barley

The effects of germination temperature on the growth of barley seedlings for phytase production were studied at 15, 20 and 25 °C for 6–10 days. The growth rate of the barley seedlings was increased as the germination temperature was increased. The initial rate of total protein production was closely coupled to that of the barley growth, and the rate of total protein production tended to increase as the germination temperature was increased. SDS–PAGE analysis of total protein from the barley seedlings showed time-dependent appearance and disappearance of protein bands. Although no significant phytase activity was detected at zero time of germination, a significant increase in phytase activity up to 7.9-fold occurred during the first several days of germination then decreased. Phosphate production (viz. phytate degradation) in the barley seedlings occurred rapidly at the beginning of germination. However, the rate of production continued to decrease with further germination. A time lag of about 1–2 days between the rate of total protein production and that of phytase production was observed. Unlike the extent of total protein production, that of phytase production was similar irrespective of germination temperature. Partial purification of a crude enzyme extract by hydrophobic interaction chromatography resulted in two phytase fractions (PI and PII). Zymogram analysis demonstrated that PI had two bands with molecular masses of about 66 and 123 kDa while PII had one band corresponding to a molecular mass of about 96 kDa. The optimal temperature for PI was found to be 55 °C, while it was 50 °C for PII. The enzyme fraction PI had a pH optimum at 6.0, whereas the optimum pH for PII was found to be 5.0. Addition of 0.1% (v/v) Tween 80 was found to increase enzyme activity significantly (i.e., 167% for PI and 137% for PII). Phytate in cereals including barley, rice, corn and soybean degraded effectively by the treatment of the barley phytases.

Kinetic Evaluation of Catalase and Peroxygenase Activities of Tyrosinase

Tyrosinase is a copper monooxygenase containing a coupled dinuclear copper active site (type-3 copper), which catalyzes oxygenation of phenols (phenolase activity) as well as dehydrogenation of catechols (catecholase activity) using O(2) as the oxidant. In this study, catalase activity (conversion of H(2)O(2) to (1/2)O(2) and H(2)O) and peroxygenase activity (H(2)O(2)-dependent oxygenation of substrates) of mushroom tyrosinase have been examined kinetically by using amperometric O(2) and H(2)O(2) sensors. The catalase activity has been examined by monitoring the initial rate of O(2) production from H(2)O(2) in the presence of a catalytic amount of tyrosinase in 0.1 M phosphate buffer (pH 7.0) at 25 degrees C under initially anaerobic conditions. It has been found that the catalase activity of mushroom tyrosinase is three-order of magnitude greater than that of mollusk hemocyanin. The higher catalase activity of tyrosinase could be attributed to easier accessibility of H(2)O(2) to the dinuclear copper site of tyrosinase. Mushroom tyrosinase has also been demonstrated for the first time to catalyze oxygenation reaction of phenols with H(2)O(2) (peroxygenase activity). The reaction has been investigated kinetically by monitoring the H(2)O(2) consumption rate in 0.5 M borate buffer (pH 7.0) under aerobic conditions. Similarity of the substituent effects of a series of p-substituted phenols in the peroxygenase reaction with H(2)O(2) to those in the phenolase reaction with O(2) as well as the absence of kinetic deuterium isotope effect with a perdeuterated substrate (p-Cl-C(6)D(4)OH vs p-Cl-C(6)H(4)OH) clearly demonstrated that the oxygenation mechanisms of phenols in both systems are the same, that is, the electrophilic aromatic substitution reaction by a (micro-eta(2):eta(2)-peroxo)dicopper(II) intermediate of oxy-tyrosinase.

Ethanol fermentation of a diluted molasses medium by Saccharomyces cerevisiae immobilized on chrysotile

In this work, the catalytic role of chrysotile support on the acceleration of alcoholic fermentation under non-aseptic conditions by Saccharomyces cerevisiae was investigated. The fermentation medium employed consisted only of diluted sugar-cane molasses. In the batch fermentations process with immobilized yeasts, the initial rate of CO2 production increased roughly 27 % during the first 30 minutes, compared to systems containing no chrysotile. A study of continuous alcoholic fermentation with chrysotile in the reactor bed showed a higher ethanol production rate at the different dilution rates investigated compared to similar fermentations without chrysotile.

Solution 17O NMR study of thermal hydrolysis in nylon 6,6

The thermal hydrolysis of nylon 6,6 between 338 and 398 K was investigated using solution 17O NMR spectroscopy. By performing the hydrolysis with isotopically 17O-enriched H 2O, it is possible to easily identify the non-volatile oxygen-containing degradation products formed during the hydrolysis of nylon. For the aging temperature range investigated, the dominant oxygen-containing degradation species are carboxylic acids, consistent with the hydrolytic cleavage of the amide bond. These 17O NMR studies allowed the temperature variation for the hydrolysis of the amide bond in nylon 6,6 to be determined with of the initial rate of carboxylic acid concentration production giving an energy of activation of ∼87±1 kJ/mol.

In vitro degradability of mature and immature leaves of tropical forage legumes differing in condensed tannin and non‐starch polysaccharide content and composition

AbstractA study was designed to examine the relationships between protein, condensed tannin and cell wall carbohydrate content and composition and the nutritional quality of seven tropical legumes (Desmodium ovalifolium, Flemingia macrophylla, Leucaena leucocephala, L pallida, L macrophylla, Calliandra calothyrsus and Clitoria fairchildiana). Among the legume species studied, D ovalifolium showed the lowest concentration of nitrogen, while L leucocephala showed the highest. Fibre (NDF) content was lowest in C calothyrsus, L Leucocephala and L pallida and highest in L macrophylla, which had no measurable condensed tannins. The highest tannin concentration was found in C calothyrsus. Total non‐structural polysaccharides (NSP) varied among legumes species (lowest in C calothyrsus and highest in D ovalifolium), and glucose and uronic acids were the most abundant carbohydrate constituents in all legumes. Total NSP losses were lowest in F macrophylla and highest in L leucocephala and L pallida. Gas accumulation and acetate and propionate levels were 50% less with F macrophylla and D ovalifolium as compared with L leucocephala. The highest levels of branched‐chain fatty acids were observed with non‐tanniniferous legumes, and negative concentrations were observed with some of the legumes with high tannin content (D ovalifolium and F macrophylla). Linear regression analysis showed that the presence of condensed tannins was more related to a reduction of the initial rate of gas production (0–48 h) than to the final amount of gas produced or the extent (144 h) of dry matter degradation, which could be due to differences in tannin chemistry. Consequently, more attention should be given in the future to elucidating the impact of tannin structure on the nutritional quality of tropical forage legumes. Copyright © 2003 Society of Chemical Industry

Auto-Pressure Transducer를 이용한 국내산 고간류의 사료가치평가

국내산 고간류의 영양학적 평가는 매우 중요하다. 본 연구는 압력센서를 이용하여 국내산 고간류의 가스발생량과 반추위발효산물과의 상관관계를 비교하고자 실시하였다. 가스발생량 측정장치는 압력센서, AD board, LED 모니터 및 real-time graphics가 설치된 컴퓨터로 구성되었다. 가스발생량과 건물소화율은 지수방정식 Pt = a + b (<TEX>$1-e^{-ct}$</TEX>)을 기초로 추정하였다.초기 가스발생량은 볏짚이 가장 높았으며 보리짚, 밀짚순이었다. 시간당 분해상수는 3.8, 2.5, 2.5%<TEX>$h^{－1}$</TEX>로서 볏짚, 보리짚, 밀짚순이었다. 전체 휘발성 지방산은 초기 12시간에 유의한 차이가 있었지만 배양 72시간 이후의 농도는 세 처리구에서 비슷한 결과를 나타냈다. 가스발생량과 건물소화율의 상관지수(<TEX>$r^2$</TEX>)는 0.76-0.83으로 밀접한 관계가 있었으며 또한 휘발성지방산과 가스발생량의 상관지수는 0.91-0.98로 매우 밀접한 관계가 있었다. 따라서 가스발생량, 건물소화율 및 휘발성 지방산의 단일상관관계는 고간류의 in vivo 소화율에서도 유사할 것으로 보인다. Accurate and rapid evaluation of the nutritional quality of Korean straws is important because of the recent increase in the use of these feedstuffs in Korean. The aim of the study was to establish with relationships between ruminal fermentation of Korean straws and in vitro gas production using a pressure transducer. The pressure transducer system includes pressure censors, AD board, LED monitor, and the computer with real-time graphics. Both gas production and DM digestibility data were fitted into the exponential equation P = a + b (1-e-<TEX>$1-e^{-ct}$</TEX>). The initial rate of gas production was highest for rice straw, followed by barley straw and wheat straw. The gas production rate of constant (c) in gas production for rice straw, wheat straw, and barley straw were 3.8, 2.5, and 2.5 <TEX>$%h^{－1}$</TEX>, respectively. Total VFA concentration (mM) produced after 72h incubation was similar among three Korean straws, even though was variable during the early (12h) fermentation. Volume of gas production was related (P> 0.05: r = 0.76 to 0.83) to DM disappearance and also strongly related (p< 0.05: r = 0.91 to 0.98) to VFA concentration at all incubation times. Linear correlation showed between gas production and DM disappearance and VFA by in vitro will be matched in in vivo digestibility.

Effects of acorn storage duration and parental tree on emergence and physiological status of Cork oak (Quercus suber L.) seedlings

This study was conducted to evaluate how parental trees and seed storage duration influenced subsequent seedling physiolo- gical status and growth. Seedling emergence rate was higher than 90% independently of the duration of seed storage or parental trees. Seed storage shortened significantly the time and increased the uniformity of seedling emergence. Consequently, the delayed seedling emergence from fresh seeds could be explained by epicotyl dormancy. Seed size varied with parental tree. Seedling growth rate was greatly affected by seed size, independently of storage treatment. Seedlings originating from large seeds (>5 g) had the fastest growth ra- tes and seedlings from the smallest seeds (<4 g) had the slowest. Final shoot height, however, depended on the duration of seed storage. The seed size and the duration of storage had a great effect on the initial rate of leaf production, but did not affect the final number of lea- ves. Leaf chlorophyll concentration was reduced as the duration of seed storage increased but was independent of parental tree (i.e., seed size). Seedling biomass was positively related to seed size. The duration of seed storage reduced the shoot/root ratio, but no significant effect was observed among parental trees. The shoot/root value of seedlings from stored seed was about 1.5 and the one of seedlings from fresh seed was about 2.

Amyloglucosidase hydrolysis of high-pressure and thermally gelatinized corn and wheat starches.

The study of glucose production using amyloglucosidase as a biocatalyst was carried out using high-pressure and thermally gelatinized corn and wheat starches. For corn starch, the measured initial rate of glucose production obtained from thermal gelatinization is faster than that obtained from the two high-pressure treatments, but the equilibrium yield of glucose was found to be similar for the three treatments. High-pressure treatments of wheat starch significantly improve the equilibrium yield of glucose compared with those obtained from the thermally gelatinized wheat starch. This difference has been related to the formation of amylose-lipid complexes during heating and could also explain previous physicochemical differences observed between high-pressure and thermally gelatinized starch.

Room-temperature ionic liquids as replacements for organic solvents in multiphase bioprocess operations

Organic solvents are widely used in a range of multiphase bioprocess operations including the liquid-liquid extraction of antibiotics and two-phase biotransformation reactions. There are, however, considerable problems associated with the safe handling of these solvents which relate to their toxic and flammable nature. In this work we have shown for the first time that room-temperature ionic liquids, such as 1-butyl-3-methylimi- dazolium hexafluorophosphate, [bmim][PF(6)], can be successfully used in place of conventional solvents for the liquid-liquid extraction of erythromycin-A and for the Rhodococcus R312 catalyzed biotransformation of 1, 3-dicyanobenzene (1,3-DCB) in a liquid-liquid, two-phase system. Extraction of erythromycin with either butyl acetate or [bmim][PF(6)] showed that values of the equilibrium partition coefficient, K, up to 20-25 could be obtained for both extractants. The variation of K with the extraction pH was also similar in the pH range 5-9 though differed significantly at higher pH values. Biotransformation of 1,3-DCB in both water-toluene and water-[bmim][PF(6)] systems showed similar profiles for the conversion of 1,3-DCB initially to 3-cyanobenzamide and then 3-cyanobenzoic acid. The initial rate of 3-cyanobenzamide production in the water-[bmim][PF(6)] system was somewhat lower, however, due to the reduced rate of 1,3-DCB mass transfer from the more viscous [bmim] [PF(6)] phase. It was also shown that the specific activity of the biocatalyst in the water-[bmim] [PF(6)] system was almost an order of magnitude greater than in the water-toluene system which suggests that the rate of 3-cyanobenzamide production was limited by substrate mass transfer rather than the activity of the biocatalyst.

Current concepts of the actions of paracetamol (acetaminophen) and NSAIDs

There is much uncertainty about the mechanism of action of paracetamol (acetaminophen). It is commonly stated that, unlike the non-steroidal anti-inflammatory drugs (NSAIDs), it is a weak inhibitor of the synthesis of prostaglandins. This conclusion is made largely from studies in which the synthesis of prostaglandins was measured in homogenized tissues. However, in several cellular systems, paracetamol is an inhibitor of the synthesis of prostaglandins with IC(50) values ranging from approximately 4 microM to 200 microM. Paracetamol is not bound significantly to plasma proteins and therefore the concentrations in plasma can be equated directly with those used in in vitro experiments. After oral doses of 1 g, the peak plasma concentrations of paracetamol are approximately 100 microM and the plasma concentrations are therefore in the range where marked inhibition of the synthesis of prostaglandins should occur in some cells. Paracetamol is metabolized by the peroxidase component of prostaglandin H synthase but the relationship of this to inhibition of the cyclooxygenase or peroxidase activities of the enzyme is unclear. Paracetamol is also metabolized by several other peroxidases, including myeloperoxidase, the enzyme in neutrophils which is responsible for the production of hypochlorous acid (HOCl). The metabolism of paracetamol by myeloperoxidase leads to the decreased total production of HOC1 by both intact neutrophils and isolated myeloperoxidase, even though the initial rate of production of HOC1 is increased. The IC(50) value, derived from inhibition of the total production of HOC1 by isolated myeloperoxidase, is 81 microM. Several NSAIDs inhibit functions of neutrophils in media containing low concentrations of protein but their effects, in contrast to that of paracetamol, are generally produced only at concentrations greater than those of the unbound drug in plasma during treatment with the NSAIDs. However, neutrophils isolated during treatment with NSAIDs, such as piroxicam, ibuprofen and indomethacin show decreased function. Paracetamol has little or no anti-inflammatory activity by itself but may potentiate the clinical activity of NSAIDs in the treatment of rheumatoid arthritis.

KINETICS OF AMMONIUM ASSIMILATION IN TWO SEAWEEDS, ENTEROMORPHA SP. (CHLOROPHYCEAE) AND OSMUNDARIA COLENSOI (RHODOPHYCEAE)

The kinetics of ammonium assimilation were investigated in two seaweeds from northeastern New Zealand, Enteromorpha sp. (Chlorophyceae, Ulvales) and Osmundaria colensoi (Hook. f. et Harvey) R.E. Norris (Rhodophyceae, Ceramiales), with the use of a recently developed method for measuring assimilation. In contrast to ammonium uptake, which was nonsaturable, ammonium assimilation exhibited Michaelis–Menten kinetics in both species. Maximum rates of assimilation (Vmax) were 27 and 12 μmol·(g DW)−1·h−1 for Enteromorpha sp. and O. colensoi, respectively, with half‐saturation (Km) constants for assimilation of 18 and 41 μM. At environmentally relevant concentrations, assimilation accounted for all of the ammonium taken up by both species. The maximum rate of assimilation in Enteromorpha sp. resembled very closely that of the ammonium assimilatory enzyme, glutamine synthetase, when activities of the latter were measured in the presence of subsaturating substrate (glutamate and ATP) concentrations. Moreover, the initial rate of glutamine production (measured with HPLC) following ammonium enrichment was almost identical to the rates determined above. The rate of ammonium assimilation was therefore determined by three independent methods, two of which involve in vivo measurements, and it is suggested that the use of assimilation kinetics may be useful when examining the nutrient relations of seaweeds.

Mathematical analysis of trickling filter response to pentachlorophenol shock load

The response of a laboratory trickling filter to a step increase in pentachlorophenol (PCP) feed concentration was analyzed using continuous stirred tank (CSTR) and plug flow reactor (PFR) models. The CSTR model provided a slightly better fit to experimental data than the plug flow model when specific growth rate, μ, and PCP-degrading biomass concentration before the shock load, X 0, were variable parameters but was clearly superior when the mean residence time, τ, was added as a third parameter. The three-parameter CSTR model accurately represented six of seven concentration response curves corresponding to step increases in PCP feed concentration of 12–165 mg l −1 and 20–150 mg l −1. The continuing improvement in system response to repetitive 20–150 mg l −1 shock loads was reflected by a monotonic increase in the optimal estimates of initial rate of biomass production.

The Effects of 6 Weeks of Creatine Monohydrate Supplementation on Performance Measures and Body Composition in Collegiate Track and Field Athletes

Thirty-six (16 men, 20 women) collegiate track and field athletes (sprinter, jumpers, and throwers) were randomly divided into a placebo (P, n = 21) group and a creatine supplemented (C, n = 15) group. Six weeks of supplementation consisted of 0.30 g?kg−1?d−1 of creatine monohydrate (Crm) or a placebo. Subjects were involved in a preseason conditioning program that consisted of interval sprinting and multijoint, large-muscle-group weight-training movements programmed in a periodized manner. Pretesting (PRE) and posttesting (POS) consisted of a 7-site skinfold analysis, hydrostatic weighing, countermovement vertical jump, static vertical jump, and 5 ± 10-second maximum cycle ergometer rides. Data were analyzed using G T analysis of variance. Significant interactions occurred for several variables. Creatine effected superior gains (percent change creatine vs. placebo) in countermovement vertical jump height (7.0 vs. 2.3%), countermovement vertical jump power index (6.8 vs. 3.1%), average cycle peak power (12.8 vs. 4.8%), cycle average power (10.8 vs. 3.1%), cycle total work (10.8 vs. 3.5%), cycle initial rate of power production (30.0 vs. 11.2%), and lean body mass. These results suggest that 6 weeks of Crm intake can favorably enhance vertical jump, power output, work capacity, and lean body mass in men and women collegiate track and field athletes following a periodized training program.

Mutations to alter Aspergillus awamori glucoamylase selectivity. II. Mutation of residues 119 and 121.

Mutations Ser119-->Glu, Ser119-->Gly, Ser119-->Trp, Gly121-->Ala and Gly121-->Ala/Ser411-->Gly were constructed in glucoamylase to change substrate specificity. Mutation Ser411-->Gly was already known to decrease glucoamylase selectivity toward isomaltose formation and to increase peak glucose yield. All mutated glucoamylases had slightly lower specific activities on maltose than on wild-type glucoamylase. Ser119-->Glu, Ser119-->Gly and Ser119-->Trp glucoamylases were about as active on isomaltose and DP 4-7 maltooligosaccharides as wild-type glucoamylase. Gly121-->Ala and Gly121-->Ala/Ser411-->Gly glucoamylases were less active. At 55 degrees C Ser119-->Glu, wild-type, Ser119-->Trp, Ser119-->Gly, Gly121-->Ala and Gly121-->Ala/Ser411-->Gly glucoamylases had progressively higher peak glucose yields, generally in the opposite order to their activities. There was also an inverse correlation between peak glucose yield and ratio of initial rate of isomaltose production from glucose condensation to that of glucose production from maltodextrin hydrolysis. The effect of mutations Gly121-->Ala and Ser411-->Gly was not additive in predicting the effect of the double mutation on the ratio or on peak glucose yield.

Kinetics of bromide oxidation by peroxo complexes of molybdenum (VI) and tungsten (VI)

The kinetics of bromide oxidation by several peroxo complexes of molybdenum(VI) and tungsten(VI) wre studied. All system obey the rate law d[Br +]/d t = k[etal complex][Br −]. At pH 1.0, we quantify the initial rate of bromine production by the spectrophotometric monitoring of the disappearance of fluorescein. The complexes and their rate constants at pH 1.0 and 25°C are MoO(O 2)(ntal) − (nta = nitrilotriacelate ( k = (1.64 ± 0.82) × 10 −4 M −1s −1), MoO(O 2)(dipic) (H 2O (dipic = pyridine-2,6-dicarboxylate) k = (5.1 ± 0.2) × 10 −4 M −1s −1), WO(O 2)(dipic)H 2O) k = (2.79 ± 0.02) × 10 −2 M −1s −1), MoO(O 2) 2(pic) − (pic = pyridine-2-carboxylate) ( k = (1.633 ± 0.001) × 10 −1 M −1s −1 and MoO(O 2) 2(H 2O) 2 ( k = 6.12 ± 0.03) × 10 −1 M −1s −1. At pH 5.0, the initial rates were measured spectrophotometrically by the production of bromophenol blue from phenol red. The complexes and their rate constants at pH 5.0 and 25°C are MoO(O 2) 2(OH)(H 2O) − ( k = (8 ± 1) × 10 −4 M −1s −1), WO(O 2) 2(OH)(H 2O) − ( k = (8.3 ± 0.7) × 10 −3 M −1s −1) and WO(O 2) 2(C 2O 4) 2− ( k = (1.3 ± 0.2) × 10 −2 M −1s −1). The 17O chemical shifts for the peroxo groups of MoO(O 2)(ntal) − (501 ppm), MoO(O 2)(dipic)(H 2O) (537 ppm), WO(O 2)(dipic)(H 2O) (364 ppm), MoO(O 2) 2(pic) − (434 ppm) and WO(O 2) 2(C 2O 4) t– (368 ppm) were measured afte enrichment with H 2 17O 2. As expected, these values correlate with the reciprocal of the transition energies of the electronic spectra. The values ν(MoO) = 930 cm −1 and β(OO) = 900 cm −1 for MoO(O 2)(nta) − are consistent with the vibrational features of similar compounds. The relationship between the spectroscopic properties and reactivity toward bromide oxidation follows previously observed patterns and may allow the reactivity of peroxometal complexes to be predicted from spectroscopic information.

The choline-leakage hypothesis for the loss of acetylcholine in Alzheimer's disease

We present a hypothesis for the loss of acetylcholine in Alzheimer's disease that is based on two recent experimental results: that beta-amyloid causes leakage of choline across cell membranes and that decreased production of acetylcholine increases the production of beta-amyloid. According to the hypothesis, an increase in beta-amyloid concentration caused by proteolysis of the amyloid precursor protein results in an increase in the leakage of choline out of cells. This leads to a reduction in intracellular choline concentration and hence a reduction in acetylcholine production. The reduction in acetylcholine production, in turn, causes an increase in the concentration of beta-amyloid. The resultant positive feedback between decreased acetylcholine and increased beta-amyloid accelerates the loss of acetylcholine. We compare the predictions of the choline-leakage hypothesis with a number of experimental observations. We also approximate it with a pair of ordinary differential equations. The solutions of these equations indicate that the loss of acetylcholine is very sensitive to the initial rate of beta-amyloid production.

The effect of simulated transport of fresh meats on their water-holding capacity as assessed by various methods

This study was designed to establish the effects of transport vibrations on the water-holding capacity of fresh non-stimulated veal and pork and electrically- and non-stimulated beef. Furthermore, drip production was followed during storage by various methods which were compared for their suitability in industrial practice and scientific research. During storage, the amount of drip increased, whilst the rate of drip formation decreased. Filter paper wetness measured at 1 day post mortem was positively correlated with drip lost over a period of 2 weeks of refrigerated storage in poly-ethylene bags (method 1) and poly-propylene containers (method 2). This suggests that the filter paper wetness test may be useful to predict drip loss of stored meat. Simulated transport did not result in higher drip losses, although a significant increase in filter paper wetness from the fresh cut surface of veal and pork was found, suggesting that transport affects the initial rate of drip production, but not the total amount of drip. In beef, transport simulation resulted in an increase in filter paper wetness from the surface of electrically-stimulated meat, stored for 1 or 2 weeks, indicating that fluid loss was elevated due to transport vibrations. However, this effect seemed to be related to the intrinsic water-holding capacity of the sample: meat with a low intrinsic water-holding capacity seemed to be more sensitive to transport vibrations than meat with a high intrinsic water-holding capacity.

Altered sensitivity of aspirin-acetylated prostaglandin G/H synthase-2 to inhibition by nonsteroidal anti-inflammatory drugs.

Aspirin (ASA) acetylates Ser516 of prostaglandin G/H synthase-2 (PGHS-2) resulting in a modified enzyme that converts arachidonic acid to 15(R)-hydroxy-eicosatetraeroic acid [15(R)-HETE]. ASA has pharmacological benefits that may not all be limited to inhibition of prostaglandin synthesis, and this study was initiated to further investigate the properties of ASA-acetylated PGHS-2 and of the mutation of Ser516 to methionine, which mimics ASA acetylation. Both the S516M mutant and ASA-acetylated form of PGHS-2 (ASA-PGHS-2) synthesize 15(R)-HETE and have apparent K(m) values for arachidonic acid within 10-fold of the apparent K(m) value for untreated PGHS-2. The time courses of turnover-dependent inactivation were similar for reactions catalyzed by PGHS-2 and ASA-PGHS-2, whereas the PGHS-2(S516M) showed a decrease in both the initial rate of 15-HETE production and rate of enzyme inactivation. The production of 15-HETE by modified PGHS-2 was sensitive to inhibition by most nonsteroidal anti-inflammatory drugs (NSAIDs), including selective PGHS-2 inhibitors. As observed for the cyclooxygenase activity of PGHS-2, the inhibition of 15-HETE production by indomethacin was time-dependent for both ASA-PGHS-2 and PGHS-2(S516M). However, two potent, structurally related NSAIDs, diclofenac and meclofenamic acid, do not inhibit either ASA-PGHS-2 or the PGHS-2(S516M) mutant. These results demonstrate that the sensitivity to inhibition by NSAIDs of the 15-HETE production by ASA-treated PGHS-2 is different than that of prostaglandin production by PGHS-2 and that Ser516 plays an important role in the interaction with fenamate inhibitors. The results also indicate that the conversion of arachidonic acid to 15-HETE by ASA-PGHS-2 is an efficient process providing a unique mechanism among NSAIDs that will not lead to arachidonic acid accumulation or shunting to other biosynthetic pathways.

Effects of physical treatment of barley and rapeseed meal in dairy cows given grass silage-based diets

Twenty-four Ayrshire cows were used to study the effects of physical treatment of barley, rapeseed meal (RSM) supplementation and heat-moisture treatment of RSM on silage intake and milk production. Experimental design was a cyclic change-over with six dietary treatments. The treatments in a 2 x 3 factorial arrangement consisted of either untreated (UB) or heat-moisture treated barley (TB), given without protein supplementation (control) or with untreated or heat-moisture treated RSM. Grass silage was given ad libitum and the concentrates at a rate of 10 kg/d. For the RSM diets, 2 kg/d of the basal concentrate was replaced with either untreated or treated RSM. Treatment of barley decreased silage intake, the effect being greater when the supplement did not contain RSM. There was no effect on milk yield, but due to the lower milk fat content, energy corrected milk yield was lower in cows given TB than in those given UB. Feeding the TB diets was also associated with lower milk urea content, and with increased milk protein content but not protein yield. Faster initial rate of gas production in vitro suggested that the treatment of barley increased the rate of fermentation. Compared with the control diets, RSM supplementation significantly increased silage intake, milk yield, milk protein content and yields of all milk constituents. Heat-moisture treatment of RSM did not produce any further production response.