Impact of L-phenylalanine supplementation on the performance of three-week-old broilers fed diets containing ochratoxin A. 1. Effects on body weight, feed conversion, relative organ weight, and mortality

An experiment with a completely randomized 2-by-3 factorial design was used to study the effects of ochratoxin A (OA; 0 and 4 mg of OA per kg) and supplemental L-phenylalanine (Phe; .0%, .8%, and 2.4% of Phe) in the diets of 3-wk-old broilers. Diets based on ground yellow corn and dehulled soybean meal were fed from Day 1 to 3 wk of age. A total of 240 male Hubbard-by-Hubbard broilers were randomly placed in battery brooders with 10 birds per pen. Each treatment was replicated 4 times. The parameters measured included mortality, BW, feed conversion, and relative organ weight. Broilers receiving OA weighed less and had poorer feed conversions than birds not receiving OA. For broilers receiving OA, the relative weights (grams of organ weight per 100 g of BW) of the liver, proventriculus, gizzard, and heart increased, while the relative weight of the bursa decreased. Supplemental Phe decreased the relative weight of the liver and increased the relative weight of the gizzard and heart. The regression slopes for Phe at 4 mg of OA per kg of diet were significantly different from 0 for BW, the relative weights of the kidney, spleen, and pancreas and approached significance for mortality (P = .065). In the absence of supplemental Phe, 42.5% of the birds died during the study when the dose level was 4 mg of OA per kg of diet. However, when Phe was supplemented at .8 and 2.4%, only 12.5 and 15.0% of the birds died, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of L-phenylalanine supplementation on the performance of three-week-old broilers fed diets containing ochratoxin A. 2. Effects on hematology and clinical chemistry

Phenylalanine was evaluated for its ability to protect broiler chickens from the toxic effects of ochratoxin A (OA). A completely randomized 2-by-3 factorial design was utilized consisting of 0, .8, and 2.4% supplemental L-phenylalanine (Phe) and of 0 and 4 mg of OA per kg of diet. The basal diet contained 14% protein. Broilers were raised in battery brooders to 3 wk of age, when blood was collected and various hematological parameters were determined. The health status of the broilers was evaluated by assaying serum for various enzyme activities and metabolites using an automated, clinical chemistry analyzer. Adding OA to the broiler diets resulted in an increased concentration of serum hemoglobin as well as increased activity for cholinesterase and gamma glutamyl transferase but in decreased activity for aspartate amino transferase, lactate dehydrogenase, and alkaline-phosphatase activity as well as decreased concentrations of total triglyceride and of inorganic phosphorus. Supplemental Phe decreased the concentrations of hemoglobin and serum glucose. The regression slopes for Phe at 4 mg of OA per kg of diet were significant for uric acid, creatinine, total protein, albumin, and cholesterol suggesting that supplemental Phe improved the health status of the broilers fed diets containing OA with respect to these parameters.

Ochratoxin A and dietary protein. 2. Effects on hematology and various clinical chemistry measurements

The health status of broilers fed diets with varying protein contents in the presence of ochratoxin A (OA) were evaluated using clinical-chemistry techniques for blood analysis. A completely randomized, 3 x 4 factorial design was utilized: 14, 18, 22, and 26% of dietary protein and 0, 2, and 4 mg/kg of OA. The broilers were raised to 3 wk of age, at which time blood was collected and various hematological parameters were evaluated. The serum was analyzed for various enzyme activities and for concentrations of metabolites and minerals using an automated, clinical-chemistry analyzer and an atomic-absorption spectrophotometer. Adding OA to the diets of broilers decreased the hemoglobin concentration, corpuscular volume, and the activity of serum alkaline and phosphatase but increased the activity of gamma-glutamyl transferase. Adding protein to the diet increased the activity of the serum aspartate aminotransferase, creatine kinase, and alkaline phosphatase. Adding OA to the diet of broilers decreased the concentrations of serum total protein, as well as the concentrations of albumen and cholesterol and increased the concentrations of serum creatinine and uric acid. The concentrations of serum total protein, albumin, urea nitrogen, and triglyceride were increased by adding protein to the diet. The concentrations of calcium, potassium, and inorganic phosphorus in the serum decreased when OA was added to the diet; but the concentrations of calcium and potassium content in the serum increased along with dietary protein. A regression analysis suggested that dietary protein was synergistic toward OA with regard to the blood levels of cholinesterase, lactate dehydrogenase, and glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Ochratoxin A and dietary protein. 1. Effects on body weight, feed conversion, relative organ weight, and mortality in three-week-old broilers

An experiment with a completely randomized 3 x 4 factorial design was used to study the effects of ochratoxin A (0, 2, and 4 mg/kg) and protein (14, 18, 22, and 26%) in three-wk-old broilers. The diets were based on ground yellow corn and dehulled soybean meal. Four hundred and eighty Hubbard x Hubbard broilers were randomly placed in battery brooders, with 10 birds per pen. Each treatment was replicated four times. Body weight increased with rising levels of protein, and decreased with rising levels of ochratoxin A (OA). The efficiency of feed utilization was improved in broilers fed 22 and 26% protein, compared with broilers fed 14 and 18% protein. The efficiency of feed utilization was lower for the birds fed 4 mg/kg of OA, compared with broilers fed 0 and 2 mg/kg of OA, respectively. Using OA increased the relative weight of the liver, kidney, spleen, pancreas, proventriculus, gizzard, and heart and also significantly decreased the relative weight of the bursa of fabricius. A significant interaction between OA and protein was seen in terms of the relative weight of the liver, pancreas, and gizzard, indicating that the rising protein levels spared the OA effect on those organs. Mortality was highest among the broilers fed 4 mg/kg of OA. Protein regression coefficients (beta's) were positive with respect to 21-day body weight and were negative for the feed:gain ratio and mortality, suggesting that protein provided beneficial effects.

Processing at the carboxyl terminus of nascent placental alkaline phosphatase in a cell-free system: evidence for specific cleavage of a signal peptide

Alkaline phosphatase is anchored to the plasma membrane by a carboxyl-terminal phosphatidylinositol glycan moiety. To investigate the biosynthesis of mature alkaline phosphatase, nascent human placental alkaline phosphatase was expressed in a cell-free system and used as substrate for in vitro processing by microsomal extracts. By monitoring the processed product with three site-directed antibodies, it was shown that microsomal extracts from CHO cells that contain other recognized processing activities also remove the carboxyl-terminal signal peptide from the preproenzyme in an apparently selective manner. This peptidase-like cleavage may be brought about by the action of a specific transamidase acting on the nascent protein in the absence of an appropriate phosphatidylinositol glycan cosubstrate.

Explaining adolescent drug use: an elaboration strategy for structural equations modeling

We report a series of analyses designed to estimate increasingly elaborated theoretical models that explain adolescent drug use. Each of the successive elaborations adds a theoretical construct to the explanatory model in order to increase our understanding of drug use by specifying in greater detail the nature of the structural relationships among the latent variables. The more detailed specification is accomplished by 1) specifying new direct effects that increase explained variance in drug use, 2) decomposing direct effects through the interpolation of hypothesized intervening variables, 3) specifying antecedents of variables that modify their direct effects, and 4) exposing suppressor effects. Where indicated, we evaluate alternative explanations of the observed relationships. We do this by controlling for common antecedent effects to reduce spuriousness or by examining different specifications of causal linkages among the explanatory constructs.

Site-directed antibodies for probing the structure and biogenesis of phosphatidylinositol glycan-linked membrane proteins: application to placental alkaline phosphatase

An immunological approach to the study of the structure and biogenesis of the phosphatidylinositol glycan (PI-G) membrane anchor at the carboxyl terminus of human placental alkaline phosphatase (PLAP) is described. Based on the protein sequence predicted from full length PLAP cDNA, two epitopes were chosen in the region of the carboxyl terminus for the production of site-directed antibodies. The exo site represents the last nine residues of preproPLAP, (res. 505-513), which is part of the sequence that is expected to be cleaved from the nascent protein during processing and addition of the PI-G tail. A second site, the endo sequence, was selected close to the expected carboxyl terminus in mature PI-G-tailed PLAP (res. 474-484 of proPLAP). The two peptides were synthesized, polyclonal antibodies to the conjugated peptides were prepared, and the antisera were characterized. Analytical methods for both synthetic peptides and proteins are presented. Preliminary applications to the isolation and characterization of the PI-G-linked carboxyl terminus of mature PLAP and to the characterization of nascent PLAP are described. The application of both carboxyl terminal-directed antibodies, and a third antibody directed to the amino terminus of mature PLAP, in studies employing mutant forms of PLAP and to the PI-G tailing process itself are discussed. The immunological approach used here for PLAP should be applicable generally to the study of other PI-G-tailed proteins.

Heat Stability of the Bile Salt-Stimulated Lipase in Human Milk Fortified with Sodium Taurocholate 1

Time-temperature relationships for heat-inactivation of the bile salt-stimulated lipase activity were compared in whole human milk and in the same product fortified to 9 mM/ml with sodium taurocholate. Heat treatments were varied from 45 to 70°C for times ranging from 15s to 40 min. Enzyme activity was more heat stable in human milk fortified with taurocholate than in control samples. The temperature required for the onset of heat inactivation at 30-min holding time was increased from 45°C for control samples to 60°C following addition of taurocholate. A temperature differential of approximately 12°C was required in the fortified milks to produce inactivation equivalent to that observed in the control milks over the heating range studied.

Aspartic acid-484 of nascent placental alkaline phosphatase condenses with a phosphatidylinositol glycan to become the carboxyl terminus of the mature enzyme

A carboxyl-terminal chymotryptic peptide from mature human placental alkaline phosphatase was purified by HPLC and monitored by a specific RIA. Sequencing and amino acid assay showed that the carboxyl terminus of the peptide was aspartic acid, representing residue 484 of the proenzyme as deduced from the corresponding cDNA. Further analysis of the peptide showed it to be a peptidoglycan containing one residue of ethanolamine, one residue of glucosamine, and two residues of neutral hexose. The inositol glycan is apparently linked to the alpha carboxyl group of the aspartic acid through the ethanolamine. Location of the inositol glycan on Asp-484 of the proenzyme indicates that a 29-residue peptide is cleaved from the nascent protein during the post-translational condensation with the phosphatidylinositol-glycan.

Effects of graded levels of dietary phosphorus on bone mineralization in the very young poult

An experiment was conducted to determine the effects of graded levels of dicalcium phosphate on bone mineralization in 1 and 3-week-old poults. Corn-soybean meal diets calculated to contain 1.5% calcium and either .35, .55, .75, .95, or 1.15% available phosphorus were fed to battery brooder reared poults for 3 weeks. Body weights and percent tibia ash were determined at 1 and 3 weeks. Body weight was not significantly affected by dietary phosphorus at either 1 or 3 weeks of age. Percent tibia ash was significantly greater in 1-week-old poults receiving a minimum of .75% available phosphorus. In 3-week-old poults, maximum tibia ash was obtained with with a minimum of .55 available phosphorus. This study suggests the level of dietary phosphorus necessary to achieve maximum tibia ash in 3-week-old poults is not sufficient for maximum tibia ash in 1-week-old poults.

Redox modification of sodium-calcium exchange activity in cardiac sarcolemmal vesicles

Na-Ca exchange activity in bovine cardiac sarcolemmal vesicles was stimulated up to 10-fold by preincubating the vesicles with 1 microM FeSO4 plus 1 mM dithiothreitol (DTT) in a NaCl medium. The increase in activity was not reversed upon removing the Fe and DTT. Stimulation of exchange activity under these conditions was completely blocked by 0.1 mM EDTA or o-phenanthroline; this suggests that the production of reduced oxygen species (H2O2, O2-.,.OH) during Fecatalyzed DTT oxidation might be involved in stimulating exchange activity. In agreement with this hypothesis, the increase in exchange activity in the presence of Fe-DTT was inhibited 80% by anaerobiosis and 60% by catalase. H2O2 (0.1 mM) potentiated the stimulation of Na-Ca exchange by Fe-DTT under both aerobic and anaerobic conditions; H2O2 also produced an increase in activity in the presence of either FeSO4 (1 microM) or DTT (1 mM), but it had no effect on activity by itself. Superoxide dismutase did not block the effects of Fe-DTT on exchange activity; however, the generation of O2-. by xanthine oxidase in the presence of an oxidizable substrate stimulated activity more than 2-fold. Hydroxyl radical scavenging agents (mannitol, sodium formate, sodium benzoate) did not attenuate the stimulation of activity observed with Fe-H2O2. Exchange activity was also stimulated by the simultaneous presence of glutathione (GSH; 1-2 mM) and glutathione disulfide (GSSG; 1-2 mM). Neither GSH nor GSSG was effective by itself and either 0.1 mM EDTA or o-phenanthroline blocked the effects on transport activity of the combination of GSH + GSSG. Treatment of the GSH and GSSG solutions with Chelex ion-exchange resin to remove contaminating transition metal ions reduced (by 40%) the degree of stimulation observed with GSH + GSSG. Full stimulating activity was restored to the Chelex-treated GSH and GSSG solutions by the addition of 1 microM Fe2+; Cu2+ was less effective than Fe2+ whereas Co2+ and Mn2+ were without effect. In the presence of 1 microM Fe2+, GSH alone produced a slight increase in transport activity, but this was markedly enhanced by the addition of Chelex-treated GSSG. The results indicate that stimulation of exchange activity requires the presence of both a reducing agent (DTT, GSH, O-.2, or Fe2+) and an oxidizing agent (H2O2, GSSG, and perhaps O2) and that the effects of these agents are mediated by metal ions (e.g. Fe2+).(ABSTRACT TRUNCATED AT 400 WORDS)

Potential of a quantal response as a mechanism for oscillatory behavior: implications for our concepts of hormonal control mechanisms

This article describes the potential of a quantal (i.e., all-or-none) response as a model for understanding the interactions between endocrine, paracrine and autocrine hormones. We review the general features of continuous and discontinuous (i.e., oscillating) quantal models including the role of a threshold. In addition, we also describe a few of the many different biochemical mechanisms which may give rise to quantal behavior. One of the more attractive schemes involves the coordinate regulation of opposing biochemical pathways resulting from phosphorylation of hormone receptors and/or rate-limiting enzymes. At least one hormone receptor (i.e., that for insulin) and many rate-limiting enzymes which control the flow of metabolites through a variety of metabolic pathways can be phosphorylated at multiple sites by one or more protein kinases. Phosphorylation may enhance or inhibit the activities of these proteins depending on which sites are modified. Furthermore, since phosphorylation of some sites on a protein may enhance the ability of phosphoprotein phosphatases to dephosphorylate other sites responsible for biological activity of the protein, phosphorylation also has the potential to produce a discontinuous quantal response. Quantal response mechanisms may alter our notions of endocrine regulation. When a quantal response mechanism is applied to a simple negative feedback model similar to that which was originally postulated to explain the interactions between gonadotropin and steroid hormonal levels, the model can account for the oscillations in hormone levels even when the input is constant. Conversely, when a graded mechanism is applied to the same negative feedback model, the model will almost certainly result in constant hormone levels. Further, the model illustrates that small changes in rate constants and thresholds of response, amplification of hormonal signals, and degradation of intermediate regulators can produce large shifts in the output of the system. These may account for the variability in hormonal levels observed in some endocrine systems. Finally, the high sensitivity of the quantal response mechanism accounts for the data which suggest that gonadotropins may play permissive rather than causal roles in regulation of gonadal function. Since increasing evidence suggests that all cells of a given type may not be equal in terms of hormonal responsiveness, measurements of response in single cells over short time periods will be needed before the role of a quantal response can be determined and endocrine regulation will be fully understood.

Effects of DEAE-dextran on infection and hemolysis by VSV. Evidence that nonspecific electrostatic interactions mediate effective binding of VSV to cells

The polycation DEAE-dextran increased the binding of VSV to BHK cells about fourfold over a wide range of VSV concentrations. The same proportion of bound virions was internalized by the cell in the presence or absence of DEAE-dextran. Viral primary RNA production was increased to the equivalent of a 4- to 4.5-fold increase in multiplicity of infection in the presence of DEAE-dextran, closely paralleling the increase in total VSV binding to the cell. Viral secondary RNA production was increased only to the equivalent of about twofold increase in multiplicity. The kinetics of both primary and secondary RNA production were indistinguishable in the presence or absence of DEAE-dextran. DEAE-dextran had to be present simultaneously with the input virions in order to enhance RNA production; addition even 30 min after infection was ineffective. Addition of the polycation DEAE-dextran was also required for appreciable VSV-induced hemolysis of human erythrocytes; erythrocytes of several other species were hemolyzed in the absence of DEAE-dextran, but hemolysis was enhanced by its presence. Maximal binding and hemolysis occurred at pH 5.0 and 37 degrees. Vesicles containing only G protein and viral lipid were 40% as hemolytic as intact virions at pH 5.0, but were inactive at pH 6.0; "spikeless" virions lacking G, or protein-free viral lipid vesicles were not hemolytic, showing that G protein is necessary for hemolysis. These results, together with other recent observations, suggest that multiple electrostatic interactions between VSV and the cell surface, rather than an affinity for specific surface molecules, mediated the productive (infection producing) binding of VSV to the cell surface.

Effects of brooding temperature and molybdenum on the turkey poult

Day-old White Broad Breastfed male turkeys were brooded for 10 days in a Honeywell environmental chamber. The chamber was configured to brood one-half of the birds at 29 C and the other half at 35 C. The poults were fed a practical corn-soy starter diet containing .8% phosphorus and 1.35% calcium. A 5 ppm molybdenum supplement was given to half the birds at each temperature. A significant (P less than or equal to .05) temperature X diet interaction occurred with both bone ash and serum phosphorus. Bone ash and serum phosphorus were significantly lower (P less than or equal to .05) in poults fed the diet supplemented with 5 ppm molybdenum at 29 C. Molybdenum supplementation did not significantly affect bone ash at 35 C but significantly increased (P less than or equal to .05) serum phosphorus at this brooding temperature. Both body weight and serum calcium were significantly higher (P less than or equal to .05) in poults brooded at 35 versus 29 C. Diets containing the molybdenum supplement did not significantly affect either body weight or serum calcium.

pH dependence of influenza A virus-induced haemolysis is determined by the haemagglutinin gene

The pH-dependent profiles of haemolysis by influenza viruses AHK/8/68 (HK virus) and APR/8/34 (PR8 virus) were found to possess characteristic differences. Both viruses were highly haemolytic at pH 5.0, but while HK virus-induced haemolysis was undetectable above pH 5.5 to 5.6,, PR8 virus-induced haemolysis persisted at higher pH values, becoming undetectable above pH 5.7 to 5.8. In order to determine whether these haemolysis profiles were genetically determined, we studied the pH dependence of haemolysis by eight recombinants of HK and PR8 viruses. The pH profile of each recombinant clearly resembled that of one parent or the other, showing that it is an inherited trait. The pH profile was found to be conferred exclusively by the haemagglutinin (HA) gene.

25-hydroxycholecalciferol-1-hydroxylase activity in heat stressed laying hens

The activity of 25-hydroxycholecalciferol-1-hydroxylase was assayed in heat stressed laying hens fed a 3.5% calcium diet with either .625% or .925% phosphorus. The activity of this enzyme in the heat stressed birds was higher than in the control birds (P less than or equal to .07). The phosphorus content of the diets had no effect on enzyme activity.

Evaluation of Microbiological Test Kits for Hydrocarbon Fuel Systems

Commercially available kits were tested for their ability to detect bacterial and fungal contamination in hydrocarbon fuel systems. The handling ease of the kits was evaluated, and their sensitivity was compared with that of conventional methods. Most kits in both laboratory and field studies compared well with laboratory methods and were sufficiently sensitive to determine contamination in shipboard fuel tanks.

Analysis of dienestrol and its dosage forms by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) analysis is described for dienestrol as a drug substance and in cream, foam, and tablet dosage forms. After incorporation of the drug or dosage form into a solvent mixture containing an internal standard, biphenyl, an aliquot was chromatographed using a reversed-phase medium, followed by UV spectrophotometric detection at 254 nm. The response of the chromatographic system was linear over a concentration range corresponding to 50-200% of the labeled amount of dienestrol. Satisfactory accuracy and precision were confirmed by analyzing cream by the standard addition method. The advantages of the HPLC method are its simplicity, speed, and sensitivity, which permit direct analysis of single-dose quantities of dienestrol.

Biocidal properties of anti-icing additives for aircraft fuels

The biocidal and biostatic activities of seven glycol monoalkyl ether compounds were evaluated as part of an effort to find an improved anti-icing additive for jet aircraft fuel. Typical fuel contaminants, Cladosporium resinae, Gliomastix sp., Candida sp., Pseudomonas aeruginosa, and a mixed culture containing sulfate-reducing bacteria were used as assay organisms. Studies were carried out over 3 to 4 months in two-phase systems containing jet fuel and aqueous media. Diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and 2-methoxyethanol were generally biocidal in aqueous concentrations of 10 to 17% for all organisms except Gliomastix, which required 25% or more. 2-Ethoxyethanol, 2-propoxyethanol, and 2-butoxyethanol were biocidal at progressively lower concentrations down to 1 to 2% for 2-butoxyethanol. The enhanced antimicrobial activity of these three compounds was attributed to cytoplasmic membrane damage because of the correlation between surface tension measurements and lytic activity with P. aeruginosa cells. The mechanism of action of the less active compounds appeared to be due to osmotic (dehydrating) effects. When all requirements are taken into account, diethylene glycol monomethyl ether appears to be the most promising replacement for the currently used additive, 2-methoxyethanol.