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PubMed2004

Environmental variables for modeling wheat yields in the southwest pampa region of Argentina.

Two types of time scales--10-day intervals (D) and phenological phases (P)--were applied to environmental variables for the development of statistical regression models relating to the southwest pampa region of Argentina, with the aim of detecting the effects of weather on wheat yields for the period 1977-1999. The parameters were grouped as meteorological and processed variables and indices. The processed variables used were total soil water availability (SWA) and the ratio of actual evapotranspiration to potential evapotranspiration (alpha), obtained from a water-balance model in which the moisture anomaly index (Z) and the Palmer drought severity index (PDSI) were calculated according to Palmer's model. For these parameters it was possible to establish the times of year and the phenological phases with the best correlation to grain yield. The regression equation for meteorological variables on a 10-day scale provides one of the best fits. Using mixed parameters, the two models, D and P, give rise to a standard error of estimate of approximately 200 kg ha(-1). Truncated models perform better on a P scale than on a D scale. The use of phenological stages improved yield assessment, particularly for those years with extreme meteorological conditions. The optimum models were tested and root-mean-square errors (RMSE) of 440 kg ha(-1) and 470 kg ha(-1) were obtained for P and D scales respectively.

Argentina↗
PubMed2003

Comparative study on the growth and yield of Pleurotus ostreatus mushroom on different lignocellulosic by-products.

Eight lignocellulosic by-products were evaluated as substrates for cultivation of the oyster mushroom, Pleurotus ostreatus ( Jacq. ex. fr) Kummer. The yields of mushroom on the different substrates were 183.1, 151.8, 111.5, 87.8, 49.5, 23.3, 13.0 and 0.0 g for composted sawdust of Triplochiton scleroxylon, rice straw, banana leaves, maize stover, corn husk, rice husk, fresh sawdust, and elephant grass, respectively. The biological efficiency (BE) followed the same pattern and ranged from 61.0% for composted sawdust to 0.0% for elephant grass. The yield of mushroom was positively correlated to cellulose ( r(2) =0.6), lignin ( r(2) =0.7) and fibre ( r(2) =0.7) contents of the substrates. Based on the yield and BE of the substrates tested, rice straw appeared to be the best alternate substrate for growing oyster mushrooms.

Agriculture↗
PubMed2004

The effect of nitrogen source on yield and glycosylation of a human cystatin C mutant expressed in Pichia pastoris.

Human cystatin C is a cysteine proteinase inhibitor with potential applications as an anti-viral agent, cancer tumor growth inhibitor, and in prevention of proteolysis during food processing. A glycosylated cystatin C mutant with increased temperature stability was developed for the latter application [Nakamura et al. (1998) FEBS Lett 427:252-254]. A recombinant variant of cystatin C [Nakamura et al. (2000) International patent no. PLTCA99/00717] with two potential sites for N-linked glycosylation was expressed in Pichia pastoris Mut(s). Little of the cystatin C produced was in the glycosylated form under fermentation conditions of pH 6, temperature 28 degrees C, methanol only feed, and ammonium hydroxide as a nitrogen source. Thus, the effect of addition of complex nitrogen sources, peptone and amino acid supplements, on the yield and glycosylation of this mutant cystatin C were investigated. A full factorial design experiment using 2-l fermenters was performed with three factors: ammonium hydroxide, peptone, and an amino acid mix, at two levels, absent or present. Peptone addition was found to have a positive, and the most significant, effect on cell specific cystatin C yield. A maximum mutant cystatin C yield of 0.82 mumol (g-dry cell weight)(-1) min(-1) was obtained when all three nitrogen sources were used together. However, under these conditions only 16% of protein was in the glycosylated form since ammonia was found to have a significant negative effect on glycosylation extent. The maximum extent of glycosylation was 30% when peptone and amino acid mix were the only nitrogen sources added.

Culture Media↗
PubMed2006

Equilibrium yields of mono- and di-lauroyl mannoses through lipase-catalyzed condensation in acetone in the presence of molecular sieves.

Modification was made to our previously reported method to predict the equilibrium yields for the synthesis of mono- and di-lauroyl mannoses through the lipase-catalyzed condensation of lauric acid and mannose in acetone in the presence of molecular sieves. HPLC and mass spectra (MS) analyses indicated that two types of dilauroyl mannoses, which would be positional isomers of each other and are designated dilauroyl mannose I and II, were produced as well as monolauroyl mannose. The predicted yields of total mannose esters and dilauroyl mannose I agreed well with the experimental ones on the whole. The equilibrium yields of dilauroyl mannose II were higher than the predicted values, while the experimental values of monolauroyl mannose were lower than the predicted values.

Acetone↗
PubMed2006

Improve islet yields and quality when clinical grade pancreata are preserved by the two-layer method.

BACKGROUND: Research grade pancreata preserved by the two-layer method (TLM) yield significantly greater numbers of islets than organs stored with University of Wisconsin solution (UW). The goal of this study was to determine whether this would hold true for pancreata that meet selection criteria for clinical grade organs. METHODS: Pancreata were chosen based upon a pre-defined set of criteria used for selecting clinical grade pancreata. Thirteen of these organs were preserved in UW and five pancreata were preserved by the TLM. Islets were isolated and evaluated according to the Edmonton protocol. RESULTS: The average preservation time was significantly longer for organ preserved with TLM (9.5 + 2.0 h) as compared to UW (5.8 + 0.6 h, p = 0.015). The pancreata of TLM group resulted in a significant increase in islet yields (3588 +/- 500 vs. 2536 +/- 312 IE/g pancreas, p<0.05). Visual scoring of islets indicated that islets were better from TLM group (8.3 +/- 0.3 vs. 7.3 +/- 0.2), and islet survival rates after culture were higher from organs stored with the TLM (87 +/- 17 vs. 55 +/- 7.4, p<0.05). Other parameters such as viability, insulin content, and stimulation index were similar between the two groups. All the preparations from the TLM group, but only 54% of preparations from the UW group, qualified for islet transplantation. The two recipients receiving islets from TLM group, daily insulin requirements were reduced and C-peptide levels were increased. CONCLUSION: Compared to storage with UW, exposure of pancreata to the TLM resulted in greater islet yields and improved quality of islets despite longer preservation period. Consequently, pancreata that meet clinical grade status should be preserved by the TLM prior to islet isolation.

Adenosine↗
PubMed2007

EUS yield in evaluating biliary dilatation in patients with normal serum liver enzymes.

The finding of common bile duct (CBD) dilatation on abdominal imaging frequently results in additional testing. It has been our impression that endoscopic ultrasound (EUS) evaluation of a dilated CBD is a low-yield examination in the setting of normal serum liver enzymes. We therefore sought to evaluate the EUS yield in evaluating CBD dilatation in patients with normal as compared to elevated serum liver enzymes. A retrospective review was performed to identify patients referred for EUS evaluation of a dilated CBD in the absence of obvious pathology on prior imaging. Charts were reviewed for patient symptoms, presence of elevated serum liver enzymes, imaging studies before EUS, and EUS findings. Exclusion criteria included clinical jaundice, known biliary stricture, mass lesion or stone, and previously sphincterotomy and/or stent placement. Forty-seven patients were identified: 32 with normal and 15 with elevated serum liver enzymes. There was no difference in mean CBD diameter between these two groups (8.51 vs. 8.79 mm, p=0.854). Of the entire group, 15 patients had undergone prior magnetic resonance cholangiopancreatography (MRCP); an additional 7 patients had undergone prior endoscopic retrograde cholangiopancreatography (ERCP). EUS findings to explain CBD dilatation were found more commonly in patients with elevated compared with normal serum liver enzymes (53% vs. 6%, p=0.001). Periampullary diverticula and choledocholithiasis were the most common findings; of 32 patients with normal serum liver enzymes, one periampullary diverticulum and one CBD stone were found, respectively. The CBD stone had been missed by prior MRCP examination. Of 15 patients with elevated serum liver enzymes, there were 3 cases of choledocholithiasis, 4 periampullary diverticula, and 1 ampullary tumor. EUS should be the test of choice for further evaluation of CBD dilatation when index imaging is normal. Although the EUS yield is low in cases of biliary dilatation in the setting of normal serum liver enzymes, its preferential use would potentially avoid unnecessary MRCP and ERCP.

Adult↗
PubMed2006

Phytohormones and rice crop yield: strategies and opportunities for genetic improvement.

To feed an estimated world population of 8.9 billion by 2050, strategies for increasing grain production must be developed. Several agronomically important traits for increasing yield, such as plant height, grain number, and leaf erectness, have recently been characterized in rice (Oryza sativa L.). These traits are regulated primarily by three phytohormones: gibberellins, cytokinins, and brassinosteroids. The control of biosynthesis and degradation of these key phytohormones is discussed in terms of its importance for normal plant growth. Genes involved in the biosynthesis and regulation of these phytohormones can be used to develop effective strategies to increase grain yield. Genetic manipulation of phytohormone-related gene expression is thus a practical strategy to generate high-yielding transgenic plants through the modification of levels and profile of endogenous phytohormones.

Agriculture↗
PubMedDate not supplied

High-yield, automated radiosynthesis of 2-(1-{6-[(2-[18F]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile ([18F]FDDNP) ready for animal or human administration.

The biomarker 2-(1-{6-[(2-[(18)F]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile ([(18)F]FDDNP) is used as a positron emission tomography (PET) imaging probe for Alzheimer's disease and other neurodegenerative diseases. A high-yield and fully automated synthesis of [(18)F]FDDNP--along with the synthesis and characterization of non-radioactive FDDNP, a fluorescent probe derived from 2-(1,1-dicyanopropenyl-2)-6-dimethylaminonaphthalene (DDNP)--are reported. Radiofluorination of the tosyloxy precursor 2-{[6-(2,2-dicyano-1-methylvinyl)-2-naphthyl](methyl)amino}ethyl-4-methylbenzenesulfonate (DDNPTs) with K(18)F/Kryptofix 2.2.2. yielded chemically (>99%) and radiochemically (>99%) pure [(18)F]FDDNP in high radiochemical yields (40-60%; n> 120), with specific activities ranging from 4 to 8 Ci/mumol at the end of synthesis (90 minutes). Both remote, semiautomated and automated synthesis procedures are described. Either approach provides a reliable method for production of large quantities (110-170 mCi from 500 mCi of [(18)F]fluoride) of [(18)F]FDDNP allowing for multiple PET experiments in the same day or for distribution of the tracer from a single cyclotron facility to PET imaging centers at various geographical distances.

2-Naphthylamine↗
PubMed1992

The influence of signs prompting motorists to yield before marked crosswalks on motor vehicle-pedestrian conflicts at crosswalks with flashing amber.

The purpose of this experiment was to evaluate the effects of signs reading "STOP HERE FOR PEDESTRIANS" alone and in conjunction with advance stop lines on pedestrian safety at multilane crosswalks with pedestrian-activated amber flashing lights. Motorist and pedestrian behaviors measured throughout this experiment included the occurrence of various types of motor vehicle-pedestrian conflicts; the distance that motorists stopped before the crosswalk when yielding to pedestrians; and the percentage of motorists yielding to pedestrians. The introduction of the sign alone 50 feet (15.15 m) before the crosswalk increased the distance before the crosswalk that motorists yielded to pedestrians and reduced the percentage of motor vehicle-pedestrian conflicts whether the flashing light was activated or not. The addition of the advance stop line was associated with further improvements in both measures.

Accidents, Traffic↗
PubMed1984

High-yield synthesis of a [3H]ethylenediamine ditetrodotoxin derivative.

[3H]Tetrodotoxin [( 3H]TTX) and a [3H]ethylenediamine derivative of TTX are the most widely used ligands for the study of the Na channel. The former ligand presents a low specific radioactivity (1 Ci/mmol) while the latter is highly labeled (30 Ci/mmol). However, its two-step synthesis, i.e., mild oxidation followed by coupling of [3H]ethylenediamine, has been described with a low overall yield of 1.7%. In this work, more favorable experimental conditions are defined for the limiting reaction, i.e., the oxidation step, using [14C]testosterone as a model molecule. Applied to the oxidation of tetrodotoxin, this procedure produces yield values of 30-50%, as determined by high-performance liquid chromatography. Moreover, two oxidized TTX molecules appear to be covalently linked to [3H]ethylenediamine, yielding a new labeled tetrodotoxin derivative with a specific radioactivity of 45 Ci/mmol and a dissociation constant of 0.6 nM for electroplax membranes.

Animals↗
PubMed1984

Improved yield of plasma membrane from mammalian cells through modifications of the two-phase polymer isolation procedure.

Modifications to the two-phase polymer gradient procedure for isolating plasma membrane from mammalian cells have resulted in greatly increased yields of purified plasma membrane. First, the cells were not treated with a membrane stabilizer (ZnCl2) prior to homogenization. This reduced the severity of homogenization required for disruption and allowed a greater proportion of the surface membrane to form large, flattened sheets that are more easily purified than the smaller fragments formed during more severe homogenization. Second, three crude fractions obtained from the homogenate (600g, 2000g, and 12,000g pellets), rather than a single, low-speed pellet (600g) containing only large sheets of membrane, were subjected to gradient centrifugation to obtain plasma membrane. This modification allowed purification of small as well as large fragments of plasmalemma and greatly increased the yield of purified membrane. Mg+2-dependent, Na+-K+-stimulated ATPase, a marker enzyme for plasma membrane, was enriched in the purified fraction by congruent to 17-fold relative to homogenate on a specific activity basis, and the yield of isolated plasma membrane averaged 70%, and was occasionally as high as 90%.

Animals↗
PubMed1977

The rise in chlorophyll a fluorescence yield and decay in delayed light emission in tris-washed chloroplasts in the 6-100 microseconds time range after an excitation flash.

Parallel measurements of the rise in chlorophyll a fluorescence yield and delayed light emission decay, after a 10 ns saturating excitation flash, have been made in tris (hydroxymethyl)aminomethane-washed chloroplasts. Various electron donor systems (Mn2+; ascorbate; reduced phenylenediamine and benzidine) were used in conjuction with different preillumination regimes to alter [P+-680], the oxidized form of the Photosystem II reaction center chlorophyll a. Conditions giving rise to high [p+ -680] resulted in only a small rise in fluorescence yield, an inhibition of a 6 microseconds component of delayed light emission. These results confirm the hypothesis that P+-680 acts as a quencher of fluorescence and that delayed light emission in the microsecond time range is due to the back reaction of P+-680 and Q-. (Q is the first "stable" electron acceptor of Photosystem II.) Two preillumination flashes are required before the full effect of Tris washing is observed in the delayed light emission decay and fluorescence yield rise; this suggests that a capacity to hold two charges exists between the Tris block and P+-680. Tris washing has no direct effect on the movement of electrons from Z (the first electron donor to P+-680. Finally, Mn2+ donates electrons to P+-680 via Z.

Ascorbic Acid↗
PubMed1978

Picosecond time-resolved study of MgCl2-induced chlorophyll fluorescence yield changes from chloroplasts.

The MgCl2-induced chlorophyll fluorescence yield changes in broken chloroplasts, suspended in a cation-free medium, treated with 3,-(3',4'-dichlorophenyl)-1,1-dimethylurea and pre-illuminated, has been investigated on a pico-second time scale. Chloroplasts in the low fluorescing state showed a fluorescence decay law of the form exp --At1/2, where A was found to be 0.052 ps-1/2, and may be attributed to the rate of spillover from Photosystem II to Photosystem I. Addition of 10 mM MgCl2 produced a 50% increase in the steady-state fluorescence quantum yield and caused a marked decrease in the decay rate. The fluorescence deday law was found to be predominantly exponential with a 1/e lifetime of 1.6 ns. These results support the hypothesis that cation-induced changes in the fluorescence yield of chlorophyll are related to the variations in the rate of energy transfer from Photosystem II to Photosystem I, rather than to changes in the partitioning of absorbed quanta between the two systems.

Chlorophyll↗
PubMed1988

Reaction of trans-4-N-acetoxy-N-acetylaminostilbene with guanosine and deoxyguanosine in vitro: the primary reaction product at N2 of guanine yields different final adducts.

The model ultimate carcinogen, trans-4-N-acetoxy-N-acetylaminostilbene (N-acetoxy-AAS), was reacted with guanosine (Guo) and deoxyguanosine (d-Guo) and the resulting adducts were purified by Sephadex LH-20 chromatography and HPLC for structure identification. A number of new adducts was identified by mass and 1H-NMR spectroscopy. The generation of all known adducts can now be explained by a common mechanism. The electrophile formed from the hydroxamic acid ester at C-beta reacts in a first step predominantly with N2 of guanine (Gua). The resulting quinone-imide intermediate reacts in a second step with either one of three nucleophiles: (1) predominantly with N3 of Gua to yield the previously described angular cyclic adducts ((5R,6R)/(5S,6S)-9-oxo-5,6,7,9-tetrahydro-imidazo(2,1-b)purines); (2) with N1 of Gua to yield linear cyclic adducts ((6R,7R)/(6S,7S)-9-oxo-5,6,7,9-tetrahydro-imidazo(1,2-a)purines); (3) with water to yield the open ring (1R,2R)/(1S,2S)-2-(N2'-guanyl)-1-hydroxyethanes. To some minor extent (1:8-1:9) the electrophile reacts first with N1 or N3 of guanine which leads to the formation of two pairs of the corresponding regioisomeric cyclic adducts. This reaction mechanism may also explain the formation of cross-links between different bases.

Carcinogens↗
PubMed1983

New high-yield synthesis of 18F-labelled 2-deoxy-2-fluoro-D-glucose.

A new high-yield synthesis for the production of 18F-2-FDG has been developed by reacting 18F-labelled acetyl hypofluorite, prepared by in situ reaction of 18F-molecular fluorine with sodium acetate in glacial acetic acid, and tri-acetyl-D-glucal at room temperature. Molecular fluorine labelled with 18F was produced by a 20Ne(d, alpha) 18F reaction. 1,3,4,6-tri-O-acetyl-2-deoxy-2-fluoro-D-glucopyranose is extracted with methylene chloride, evaporated to dryness and hydrolyzed, yielding 98% radiochemically pure 18F-2-FDG. Overall radiochemical yield is about 24 +/- 3%. The specific activity of the final product at the end of synthesis is about 25.38 GBq/mmol (685 mCi/mmol). The synthesis time is approximately 60 min. The synthesis proves that small medical cyclotrons are able to produce 18F-molecular fluorine at the levels needed for the synthesis of 18F-2-FDG used in functional imaging with positron emission tomography.

Deoxy Sugars↗
PubMed1984

A new, simple, high-yield synthesis of "no-carrier-added" 11C-labelled DMO.

This paper describes a fast (20 min), convenient, and high yield synthesis of "no-carrier-added" 11C-labelled 5,5-dimethyloxazoladine-2,4-dione (DMO). During the synthesis [11C]phosgene is reacted in situ with 2-hydroxy-2-methylpropionamide in the presence of KOH for 20 min in a -5 degrees C bath and then for 5 min at room temperature. Filtration through a reverse-phase (C18) Sep-Pack column purifies the final product. This synthesis yields about 40 mCi of 11C-labelled DMO (radiochemical yield 40-60%) with a chemical purity exceeding 98% and a radiochemical purity exceeding 99%. The specific activity at the end of the synthesis is 80 Ci/mmol.

Carbon Radioisotopes↗
PubMed1985

Measurement of yield and cross section for the 27Al (gamma,2p) 25Na reaction with a clinical linear accelerator.

A clinical electron linear accelerator was adapted for continuous energy selection and used to measure bremsstrahlung yield for the photonuclear reaction 27Al (gamma,2p) 25Na from 24.0 to 32.0-MeV in 0.25 MeV steps. A germanium detector was used to measure the number of photoproduct gamma-rays emitted. The yield values were analyzed for photonuclear cross section using PHONUC II, a program especially adapted for use with yield data from thick-target bremsstrahlung. The cross section shows distinct resonance peaks at 26.3 +/- 0.3, 27.3 +/- 0.4 and 30.3 +/- 0.5 MeV. Possible theoretical origins of these resonances and applications of the reaction in accelerator energy calibration are discussed.

Aluminum↗
PubMed1985

Anisotropic yield behavior of bone under combined axial force and torque.

In this study the yield behavior of cortical bone was determined under combined loading conditions involving tension, compression and torsion. The axis of each test sample coincided with the long bone axis. To minimize viscoelastic behavior, tests were conducted using an effective strain rate in the range of 0.01-0.06 s-1. Experimental yield loci for bovine and human cortical bone were determined using a strain offset technique to determine the 'common yield point' for combined loading. Several failure criteria which have been used for composite materials were examined for applicability to the experimental results. Data were obtained for bovine and human tibial and femoral bone. The Tsai-Wu criterion was in best agreement to the test data, although Hill's criterion could describe the individual compression-torsion or tension-torsion regimes with good accuracy.

Animals↗