The isolated supported canine heart: a model for the evaluation of drug effects on regional myocardial blood flow

The present investigation was designed to determine the effect of propranolol on regional myocardial blood flow and oxygen consumption (MVO2) in the isolated supported dog heart preparation perfused at a constant coronary blood flow. The transmural distribution of blood flow, determined by the radioactive microsphere technique, was expressed as the epicardial/endocardial blood flow ratio (epi/endo). Propranolol (0.5 mg/kg i.v.) produced a significant decrease in heart rate and myocardial contractile force and an increase in coronary artery perfusion pressure due to an increase in coronary vascular resistance. These hemodynamic changes were accompanied by significant decreases in epi/endo (increased endocardial perfusion) and MVO2. Reduction of perfusion pressure to control by a decrease in total coronary blood flow produced no further change in epi/endo or MVO2. However, increasing heart rate to control increased epi/endo to predrug levels. Contractile force and MVO2 remained reduced below control. Norepinephrine infusion (1 mug/min intracoronary) produced a significant increase in heart rate and contractile force and decrease in perfusion pressure. These changes were accompanied by an increase in epi/endo and MVO2. Propranolol (0.5 mg/kg i.v.) abolished the response to norepinephrine. Propranolol may produce beneficial effects in angina pectoris by a decrease in epi/endo (via a reduction in heart rate) and MVO2 and by beta adrenergic blockade of the deleterious effects of catecholamines.     

Isolation of principal and basal cells from the epithelium of the hamster caput epididymidis by unit gravity sedimentation

A technique for the isolation of principal and basal cells from the epithelium of the hamster caput epididymides by unit gravity sedimentati on is described. The technique enzymatically disaggregates cells comprising the caput epididymides, and the resulting mixture of disperse d cells is separated by sedimentation in a shallow bovine serum albumin gradient at unit gravity into populations of spermatozoa, erythrocytes and several nucleated types. The separated somatic cell types and the homogeneity of each population were identified by light and electron microscopy. The purest fractions of the 6 populations, from smallest to largest, contained an average of 84% erythrocytes, 76% basal cells, 82% fibroblasts and intraepithelial lymphocytes, 68% small principal cells and 34% smooth muscle cells or 58% large principal cells. Cell viability following sedimentation was excellent, as concluded from elect ron micrographs revealing adenosine triphosphate content and fine struct ure. This technique should enable critical analyses of epididymal function in isolated epithelial cells.     

The fine structure of a microplate-microtubule array, microfilaments and polyhedral body associated microtubules in several species of Anabaena

A microplate-microtubule array was observed in Anabaena sp. (B-378). This structure consists of an arched plate, about 8 nm thick, and various microtubules, 12 nm in diameter and 50 nm long, arranged in rows. The microtubules project at right angles from one side of the plate into the cytoplasm or towards the plasma membrane. Up to twelve microplate-microtubule arrays were observed in a single section of a cell. Microfilaments, about 2.8 nm in diameter and of undetermined length, were observed in four isolates of Anabaena. The microfilaments were always found in bundles, nwhich varied in size, up to 0.63 mum across and 0.91 mum long. Microtubules, 10 nm in diameter and about 150 nm in length, were observed associated with one facet of polyhedral bodies in 8 out of 20 isolates of Anabaena. The microtubules occurred in groups of up to 20 or more, and were always oriented with the long axis parallel to the facet of a polyhedral body. In cross section, the microtubules had an electron transparent lumen 5 nm wide and a wall 2.5 nm thick. These structures are compared to previously described microtubules and microfilaments.     

Sex and age differences in pulmonary mechanics in normal nonsmoking subjects

This study was performed to determine whether stimulation of the carotid chemoreceptors increases total or regional cerebral blood flow and whether activation of arterial chemoreceptors contributes to cerebral vasodilation during systemic hypoxemia. In anesthetized and ventilated dogs, carotid chemoreceptors were stimulated with nicotine or hypoxic and hypercapnic blood. To measure total and regional cerebral blood flow, we used labeled 15-mu microspheres. Stimulation of chemoreceptors did not increase cerebral blood flow or produce significant redistribution of cerebral blood flow, even though the chemoreflex was intact in these animals (as manifested by vasoconstriction in muscle, kidney, and small bowel) and the cerebral vessels dilated in response to systemic hypercapnia. In other studies in anesthetized, ventilated dogs and rhesus monkeys, cerebral vasodilator responses to systemic hypoxemia were observed before and after denervation of carotid and aortic chemoreceptors. Systemic hypoxemia produced large and equivalent increases in cerebral blood flow before and after chemodenervation. We conclude that stimulation of carotid chemoreceptors does not produce cerebral vasodilation and that chemoreceptors do not contribute significantly to cerebral vasodilation during systemic hypoxemia.     

Effects of germination on the activities of amylases and phenolic enzymes in sorghum varieties grouped according to food end‐use properties

Fifty sorghum varieties were screened to determine the effects of germination on levels of starch, α‐amylase, β‐amylase, phenylalanine ammonia lyase (PAL), peroxidase (POX) and polyphenol oxidase (PPO). Germination decreased starch content, with amylose being more degraded than amylopectin. In germinated grain, α‐amylase activity increased several‐fold in all varieties, whereas β‐amylase activity did not increase uniformly and even decreased in some varieties. Activity of the key enzyme in phenolic biosynthesis, PAL, was detected in only half of the varieties before germination but in all of them after germination. PPO was not activated in germinated sorghum grains, whereas POX activity increased up to tenfold in some varieties. Zymography revealed that germination induced de novo synthesis of several POX isoenzymes, among which an anionic POX isoenzyme (pI 3.1) was ubiquitously present. Amylase and phenolic enzyme activities could be correlated with grain and plant agronomic characteristics. The use of sorghum varieties for local dishes such as ‘tô’, ‘dolo’, couscous and thin porridge could be correlated with amylase and phenolic enzyme activities and the contents of their substrates. The biochemical constituents determined are useful markers for selection of varieties for food utilisation with special emphasis on infant porridges. Copyright © 2006 Society of Chemical Industry     

Safety aspects of microbial enzyme technology,exemplified by the safety assessment of an immobilized lipase preparation,lipozyme™

The historical use of enzymes for food processing is briefly reviewed. The manufacturing process of microbial food enzymes is described including the fundamental purity criteria recommended by Joint FAO/WHO Expert Committee on Food Additives (JECFA) and Food Chemicals Codex. Principles for safety evaluation focus on the possible presence of toxic contaminants in the commercial enzyme preparation. Possible sources of any undesirable contaminants include the raw materials used, the properties of the production strain, contamination with foreign micro‐organisms, use of additives and processing aids in recovery of the enzyme. Systems for design of toxicology programmes are reviewed. A case study is given summarizing the safety evaluation of an immobilized lipase used for the interesterification of fats and oils. Based upon a no‐effect level derived from in vitro and animal feeding studies it is concluded that the enzyme is safe for the intended use.

The safety of the enzyme part of the immobilized preparation is documented by a thorough toxicology programme. The safety of the carrier, a phenol formaldehyde based ion‐exchange resin, is documented by leakage analysis of extractable materials under forced conditions, as well as by a feeding study employing a fat treated with the immobilized enzyme.     

Synergistic and suppressive effects of dietary phenolic acids and other phytochemicals from cereal extracts on nuclear factor kappa B activity

In this study the combinatorial action of the main phenolic acids (ferulic, caffeic, p-coumaric and sinapic acids) found in extracts of free (ME) and bound phenolic acids (HE) from oat, barley and wheat flour on the modulation of NF-κB activity was investigated. The results show that combination of phenolic acids in low concentrations (<0.1 μg/ml) has a significant synergistic, or enhanced effect, on NF-κB activity, while their combination in high concentrations (0.3–70 μg/ml) helps to suppress the strong effect obtained by individual solutions of ferulic and p-coumaric acids. The modulation of NF-κB activity observed by HE extracts is the effect of combinatorial action of the phenolic acids present therein, while the modulation of NF-κB activity observed with ME extracts is the result of combinatorial action of phenolic acids together with other phenolic compounds present in the extracts. These results increase the knowledge about the health promoting effect from cereal consumption and dietary phenolic acids.     

Reduction of Aflatoxin in Corn by High Voltage Atmospheric Cold Plasma

This study investigated the efficacy of high voltage atmospheric cold plasma (HVACP) treatment on degradation of aflatoxin in corn. Gas type (Air, MA65), relative humidity (5, 40, 80% RH), treatment time (1, 2, 5, 10, 20,and 30 min), mode of reaction, post-treatment storage, stirring of corn material were parameters investigated on degradation of aflatoxin by HVACP treatment. Generation of reactive gas species was characterized with optical emission spectroscopy and measured with dragger tubes. Generation of reactive gas species are influence by gas type and relative humidity. Higher concentration of ozone and NOx were generated during HVACP treatment in MA65 than in air and with lower relative humidity. Aflatoxin in corn could be rapidly degraded by HVACP treatment. Aflatoxin in corn was degraded by 62% and 82% by 1 and 10 min HVACP treatment in RH 40% air, respectively. The degradation kinetics of aflatoxin by HVACP treatment follows a logistic model. Higher degradation of aflatoxin was achieved in gas MA65, at higher relative humidities (40%, 80%). Direct or indirect HVACP treatment was equally effective in degrading aflatoxin in corn. Stirring the corn sample during HVACP treatment and post-treatment storage increased aflatoxin degradation in corn by HVACP treatment.     

Dairy cows seek isolation at calving and when ill

Dairy cows are typically gregarious, but isolate themselves in the hours before calving when kept on pasture. Self-isolation is also a common behavior of ill animals. The objectives of this study were to determine if dairy cows would (1) isolate to calve when housed indoors in an individual maternity pen and (2) continue to isolate when ill after calving. We selected individuals from a pool of 79 multiparous Holstein dairy cows based on inclusion criteria created to address each objective. Cows were moved from a group pen to 1 of 10 adjacent maternity pens. Half of these individual pens were partially covered with plywood, creating a secluded corner as well as a window that provided visual access to the group pen. The other individual pens were uncovered on all sides. For our first objective, we selected 39 cows that were moved into the maternity pens >8 h before calving (partially covered: n = 19; uncovered: n = 20). For our second objective, we selected 18 cows housed in the partially covered pens: 9 cows with high rectal temperature after calving and signs of an infectious disease (mastitis, metritis, pneumonia, or some combination), and 9 healthy cows paired with ill cows based on the amount of time they spent in the maternity pen before calving. Ten-minute scan sampling was used to record the location and lying time from 6 h before to 72 h after calving. Individual feed intake was measured after calving. Binomial tests were used to determine if cows in both pen types were more likely to calve in the corner or window side of the pen. Repeated-measures ANOVA were used to determine if cows used the corner more as calving approached and if ill cows spent more time lying or more time in the corner compared with healthy cows in the 72 h after calving. Cows in the uncovered pens were equally likely to calve on both sides of the pen (10 vs. 10), but 79% of cows in the partially covered pens calved on the corner side of the pen (15 vs. 4). Cows in the partially covered pens used the corner side of the pen more in the 1 h before and after calving compared with those housed in the uncovered pens. Ill cows housed in the partially covered pens ate less, tended to spend more time lying down, and spent more time in the corner of the pen compared with healthy cows. These results indicate that periparturient dairy cows seek seclusion to calve and when ill, which suggests that adding a secluded area to maternity and hospital pens may be beneficial.