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PubMed2006

Pre-partum monensin supplementation improves body reserves at calving and milk yield in Holstein cows dried-off with low body condition score.

The objective of this study was to determine the effect of a monensin controlled-release capsule administered intraruminally at drying-off on body condition score (BCS) at calving, milk yield, fertility and concentration of energy-related blood metabolites in Holstein cows dried-off with low BCS (< or = 3.0, scale 1 to 5 with a 0.25 point of increment). Between July and August, 2001, 220 cows from parity 2 or more and dried-off 50-70 days before expected parturition, with a BCS < or = 3.0 were randomly assigned to either a treatment group (n=110; oral capsule of monensin releasing 335 mg/day for 95 days) or a control group (no capsule, n=110). At assignment, on day 21 before expected parturition, at calving, and at 7, 14, and 21 days in milk a blood sample was obtained from a random sub sample of 10 cows per group. Effects of monensin on serum NEFA, BHBA and glucose were measured. Milk yield, milk fat and protein content (%) at DHIA test days during the entire lactation, 305 ME milk production and reproductive responses were compared. Monensin significantly improved BCS at calving, increased milk yield at test days 4 and 8, decreased the percentage of milk protein, did not change the percentage of milk fat, and decreased NEFA and BHBA during the post-partum period.

Animal Feed↗
PubMed2006

Spectral power distribution and quantum yields of Sm3+-doped heavy metal tellurite glass under the pumping of blue lighting emitting diode.

Quantum yields for multichannel transition emissions have been determined in Sm3+-doped heavy metal tellurite glass under the pumping of blue lighting emitting diode for the first time. To achieve this goal, the necessary fluorescence spectra were measured and calibrated in an integrating sphere, which was connected to a CCD detector with a 400 microm-core optical fiber. The spectral power distribution of the sample under the blue LED pumping was derived from the measured spectra firstly, and then the quantum yields for the visible emissions of Sm3+ were calculated based on the distribution and the total quantum yields in visible region is 7.55%. For accurate measurements, integrating sphere method is proved to be a reliable and reproducible way to characterize luminescence and laser materials.

Glass↗
PubMed2004

Metabolic changes in follicular fluid of the dominant follicle in high-yielding dairy cows early post partum.

Characteristics of the intrafollicular environment to which the preovulatory oocyte is exposed may be one of the major factors determining subsequent fertility. The aim of our study was to examine to what extent metabolic changes that occur in early post partum high-yielding dairy cows are reflected in the follicular fluid (FF) of the dominant follicle (>8 mm). Nine blood samples were taken per cow from nine high-yielding dairy cows between 7 days before and 46 days after parturition. From Day 14 post partum on and together with blood sampling, FF samples of the largest follicle were collected from the same cows by means of transvaginal follicle aspiration. Serum and FF samples were analyzed using commercial clinical and photometric chemistry assays for glucose, beta-hydroxybutyrate (beta-OHB), urea, total protein (TP), triglycerides (TG), non-esterified fatty acids (NEFA) and total cholesterol (TC). All cows lost body condition during the experimental period (0.94+/-0.09 points) illustrating a negative energy balance during the experimental period. In FF, glucose concentrations were significantly higher and the TP, TG, NEFA and TC concentrations were significantly lower than in serum (P<0.05). The concentrations of glucose, beta-OHB, urea and TC in serum and in FF changed significantly over time (P<0.05). Throughout the study, changes of all metabolites in serum were reflected by similar changes in FF. Especially for glucose, beta-OHB and urea the correlations were remarkably high. The results from the present study confirm that the typical metabolic adaptations which can be found in serum of high-yielding dairy cows shortly post partum, are reflected in follicular fluid and, therefore, may affect the quality of both the oocyte and the granulosa cells.

3-Hydroxybutyric Acid↗
PubMedDate not supplied

Augmentation of tissue ATP level during digestion using preoxygenated perfluorocarbon results in high islet yield-new strategy for islet isolation.

BACKGROUND: Recently, preservation using oxygenated perfluorocarbon (the two-layer method) has shown beneficial effects on islet yield and viability. In this paper, we apply this concept on isolation processes to examine the effectiveness of oxygenation. METHODS: Rat pancreata were digested using four different methods: (groups 1A, 1B, 2A, and 2B) with or without oxygenated perfluorocarbon in groups 1 and 2, respectively. Adenosine was added into the collagenase solution in subgroup A whereas it is not added in subgroup B. RESULTS: Tissue oxygen tension in group 1 was about 0 during digestion; whereas it rapidly reached about 300 mm Hg and was maintained in group 2. Tissue ATP level just after laparotomy (control) was 4.2 +/- 0.7 micromol/g dry weight. The ATP levels after digestion were 0.12 +/- 0.03 in group 1A (P < 0.01 vs control); 0.70 +/- 0.10 in group 1B (P < 0.01 vs control); 0.30 +/- 0.18 in group 2A (P < 0.01 vs control); and 2.90 +/- 0.80 in group 2B (P = 0.19 vs control). Islet yields (IEQ/pancreas) were 1600 +/- 400 in group 1B; 1400 +/- 400 in group 1B; 1300 +/- 400 in group 2A; and 2400 +/- 100 in group 2B. The amount in group 2B was significantly greater than that in the other three groups. CONCLUSIONS: Oxygen provision by preoxygenated perfluorocarbon itself showed no beneficial effect on islet yield. However, if oxygen provision was associated with adenosine administration into the pancreas, tissue ATP levels after digestion were well maintained, and a greater number of islets were retrieved.

Adenosine Triphosphate↗
PubMed2005

Experimental quantification of cavitation yield revisited: focus on high frequency ultrasound reactors.

Acoustic cavitation plays an important role in enhancing the reaction rate of chemical processes in sonochemical systems. However, quantification of cavitation intensity in sonochemical systems is generally limited to low frequency systems. In this study, an empirical determination of cavitation yield in high frequency ultrasound systems was performed by measuring the amount of iodine liberated from the oxidation of potassium iodide (KI) solution at 1.7 and 2.4 MHz. Experiments for determining cavitation were carried out at various solute (KI) concentrations under constant temperature, obtained by direct cooling of the solution and variable temperature conditions, in the absence of external cooling. Cavitation yield measurements, reported in this work, extend previously reported results and lend credence to the two step reaction pathway in high frequency systems. Additionally, the concentration of KI and temperature affect the cavitation yield of a system such that the iodine production is proportional to both conditions. It is proposed that direct cooling of sonicated KI solution may be advantageous for optimization of cavitation intensity in high frequency sonochemical reactors.

Chemical Fractionation↗
PubMed2004

Faecal bacteria yields in artificial flood events: quantifying in-stream stores.

Stream sediments have been recognised as an in-channel store of faecal contamination that can be mobilised during floods or other sediment-disturbing events. We studied this store of faecal contamination by creating artificial floods during dry weather when, in the absence of overland flow from the catchment, the only source of faecal bacteria was stores within the channel. Artificial floods, created by releasing water from a supply reservoir, increased the E. coli concentration in the water column by two orders of magnitude, from a background level of 10(2) cfu per 100 mL to over 10(4) cfu per 100 mL. The bacterial peak concentrations and yields declined systematically through a triplicate flood series. The size of the total in-channel store, calculated as the sum of yields of an infinite series of artificial floods, was approximately 10(8) cfu m(-2) of streambed area. Direct measurements of sediment E. coli found few sites (only those associated with cattle crossings) with areal concentrations as high as 10(8) cfu m(-2), consistent with flood yields. Concentrations of E. coli in the biofilms on exposed rocks were orders of magnitude lower, indicating that exposed rocks were not a source of E. coli released by the artificial floods.

Animals↗
PubMed2004

Mouse embryonic stem cells efficiently lipofected with nuclear localization peptide result in a high yield of chimeric mice and retain germline transmission potency.

Embryonic stem (ES) cells are an important tool in developmental biology, genomics, and transgenic methods, as well as in potential clinical applications such as gene therapy or tissue engineering. Electroporation is the standard transfection method for mouse ES (mES) cells because lipofection is quite inefficient. It is also unclear if mES cells treated with cationic lipids maintain pluripotency. We have developed a simple lipofection method for high efficiency transfection and stable transgene expression by employing the nonclassical nuclear localization signal M9 derived from the heterogeneous nuclear ribonucleoprotein A1. In contrast to using 20 microg DNA for 10 x 10(6) cells via electroporation which resulted in 10-20 positive cells/mm2, M9-assisted lipofection of 2 x 10(5) cells with 2 microg DNA resulted in > 150 positive cells/mm2. Electroporation produced only 0.16% EGFP positive cells with fluorescence intensity (FI) > 1000 by FACS assay, while M9-lipofection produced 36-fold more highly EGFP positive cells (5.75%) with FI > 1000. Using 2.5 x 10(6) ES cells and 6 microg linearized DNA followed by selection with G418, electroporation yielded 17 EGFP expressing colonies, while M9-assisted lipofection yielded 72 EGFP expressing colonies. The mES cells that stably expressed EGFP following M9-assisted lipofection yielded > 66% chimeric mice (8 of 12) and contributed efficiently to the germline. In an example of gene targeting, a knock-in mouse was produced from an ES clone screened from 200 G418-resistant colonies generated via M9-assisted lipofection. To our knowledge, this is the first report of generation of transgenic or knock-in mice obtained from lipofected mES cells and this method may facilitate large scale genomic studies of ES developmental biology or large scale generation of mouse models of human disease.

Animals↗
PubMed2006

Relationship between machine-derived smoke yields and biomarkers in cigarette smokers in Germany.

In order to determine whether smokers of cigarettes in the contemporary yield ranges of the German market (0.1-1.0mg nicotine, 1-10mg tar) differ in their actual exposure to various smoke constituents, we performed a field study with 274 smokers and 100 non-smokers. The following biomarkers were determined: In 24-h urine: Nicotine equivalents (molar sum of nicotine, cotinine, trans-3'-hydroxycotinine and their respective glucuronides), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, metabolite of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, NNK), 3-hydroxypropylmercapturic acid (metabolite of acrolein), trans,trans-muconic acid, S-phenylmercapturic acid (metabolites of benzene), 1-hydroxypyrene (metabolite of pyrene); in saliva: Cotinine and trans-3'-hydroxycotinine; in exhaled air: Carbon monoxide; in blood: Methyl-, hydroxyethyl-, cyanoethyl- (biomarker of acrylonitrile) and carbamoylethylvaline (biomarker of acrylamide) hemoglobin adducts. All biomarkers were found to be significantly higher in smokers compared to non-smokers and showed strong correlations with the daily cigarette consumption. Biomarker levels and per cigarette increases in smokers were at most weakly related to the machine-derived smoke yields. It is concluded that machine-derived yields of cigarettes from the contemporary German cigarette market have little or no impact on the actual smoking-related exposure determined by suitable biomarkers.

Adolescent↗
PubMed2000

Oxygen yield from single turnover flashes in leaves: non-photochemical excitation quenching and the number of active PSII.

O(2) evolution from single turnover flashes of up to 96 micromol absorbed quanta m(-2) and from multiple turnover pulses of 8.6 and 38.6 ms duration and 12800 and 850 micromol absorbed quanta m(-2) s(-1) intensity, respectively, was measured in sunflower leaves with the help of zirconium O(2) analyser. O(2) evolution from one flash could be measured with 1% accuracy on the background of 10-50 micromol O(2) mol(-1). Before the measurements leaves were pre-adapted either at 30-60 or 1700 micromol quanta m(-2) s(-1) to induce different non-photochemical excitation quenching (q(N)). Short (1 min) exposures at the high light that created only energy-dependent, q(E) type quenching, caused no changes in the O(2) yield from saturating flashes or pulses that could be related to the q(E) quenching, but the yield from low intensity flashes and pulses decreased considerably. Long 30-60-min exposures at the high light induced a reversible inhibitory, q(I) type quenching that decreased the O(2) yield from both, saturating and limiting flashes and pulses (but more from the limiting ones), which reversed within 15 min under the low light. The results are in agreement with the notion that q(E) is caused by a quenching process in the PSII antenna and no changes occur in the PSII centres, but the reversible (15-30 min) q(I) quenching is accompanied by inactivation of a part of PSII centres.

Helianthus↗
PubMed2002

cAMP-induced modulation of the growth yield of Saccharomyces cerevisiae during respiratory and respiro-fermentative metabolism.

The aim of this study was to investigate the effects of an overactivation of the cAMP/protein kinase A signaling pathway on the energetic metabolism of growing yeast. By using a cAMP-permeant mutant strain, we show that the rise in intracellular cAMP activates both anabolic and catabolic pathways. Indeed, different physiological patterns were observed with respect to the growth condition: (i) When cells were grown with a limiting amount of lactate, cAMP addition markedly increased the growth rate, whereas it only slightly increased the mitochondrial and cellular protein content. In parallel, the respiratory rate increased and the growth yield, as assessed by direct microcalorimetry, was not significantly modified by cAMP. (ii) Under conditions where the growth rate was already optimal (high lactate concentration), exogenous cAMP led to a proliferation of well-coupled mitochondria within cells and to an accumulation of cellular and mitochondrial proteins. This phenomenon was associated with a rise in the respiratory activity, thus leading to a drop in the growth yield. (iii) Under conditions of catabolic repression (high glucose concentration), cAMP addition markedly increased the fermentation rate and decreased the growth yield. It is concluded that overactivation of the cAMP/PKA pathway leads to uncoupling between biomass synthesis and catabolism, under conditions where an optimal growth rate is sustained by either a fermentative or a respiratory metabolism.

Culture Media↗
PubMed1999

Theories for kinetics and yields of fluorescence and photochemistry: how, if at all, can different models of antenna organization be distinguished experimentally?

The models most commonly used to describe the antenna organization of the photosynthetic membrane are the connected units model and the domain model. The theoretical descriptions of the exciton dynamics according to these models are reviewed with emphasis on a common nomenclature. Based on this nomenclature we compare for the two models the kinetics and yields of photochemistry and fluorescence under non-annihilation and annihilation conditions both under continuous light and under flash excitation. The general case is considered, that all initially open reaction centers become gradually closed and that exciton transfer between photosynthetic units (PSUs) is possible. Then, calculated kinetics and yields depend on the model assumptions made to account for the exciton transfer between PSUs. Here we extend the connected units model to flash excitation including exciton-exciton annihilation, and present a new simple mathematical formalism of the domain model under continuous light and flash excitation without annihilation. Product and fluorescence yields predicted by the connected units model for different degrees of connectivity are compared with those predicted by the domain model using the same sets of rate constants. From these calculations we conclude that it is hardly possible to distinguish experimentally between different models by any current method. If at all, classical fluorescence induction measurements are more suited for assessing the excitonic connectivity between PSUs than ps experiments.

Journal Article↗
PubMed1988

A new method for high yield purification of type beta transforming growth factor from human platelets.

A new method was developed for the purification of type beta transforming growth factor from human platelets. This method is a three-step procedure including gel filtration, weak cation exchange HPLC and reverse phase HPLC. All steps are carried out at low pH using exclusively volatile acidic buffer solutions. The sterile conditions and easy removal of salt by lyophilization facilitate the quantification of the growth factor in biological assays. Based on immunological characterization the purified acid-stable, highly basic transforming growth factor beta is the beta 1 form. Using the present method pure platelet TGF beta 1 is obtained in very high yield. 40 units of outdated human platelets yield 800 micrograms pure TGF beta 1, which is about a 10-20 fold higher yield than reported for other purification procedures.

Blood Platelets↗
PubMed1983

A master equation theory of fluorescence induction, photochemical yield, and singlet-triplet exciton quenching in photosynthetic systems.

A master equation theory is formulated to describe the dependence of the fluorescence yield (phi) in photosynthetic systems on the number of photons (Y) absorbed per photosynthetic unit (or domain). This theory is applied to the calculation of the dependence of the fluorescence yield on Y in (a) fluorescence induction, and (b) singlet exciton-triplet excited-state quenching experiments. In both cases, the fluorescence yield depends on the number of previously absorbed photons per domain, and thus evolves in a nonlinear manner with increasing Y. In case a, excitons transform the photosynthetic reaction centers from a quenching state to a nonquenching state, or a lower efficiency of quenching state; subsequently, absorbed photons have a higher probability of decaying by radiative pathways and phi increases as Y increases. In case b, ground-state carotenoid molecules are converted to long-lived triplet excited-state quenchers, and phi decreases as Y increases. It is shown that both types of processes are formally described by the same theoretical equations that relate phi to Y. The calculated phi (Y) curves depend on two parameters m and R, where m is the number of reaction centers (or ground-state carotenoid molecules that can be converted to triplets), and R is the ratio phi (Y leads to infinity)/(Y leads to 0). The finiteness of the photosynthetic units is thus taken into account. The m = 1 case corresponds to the "puddle" model, and m leads to infinity to the "lake," or matrix, model. It is shown that the experimental phi (Y) curves for both fluorescence induction and singlet-triplet exciton quenching experiments are better described by the m leads to infinity cases than the m = 1 case.

Kinetics↗
PubMed1992

Effects of domain connection and disconnection on the yields of in-plane bimolecular reactions in membranes.

It has recently been shown (Vaz, W.L.C., E.C.C. Melo, and T.E. Thompson. 1989. Biophys. J. 56:869-875; 1990. Biophys. J. 58:273-275) that in lipid bilayer membranes in which ordered and disordered phases coexist, the ordered phase can form a two-dimensional reticular structure that subdivides the coexisting disordered phase into a disconnected domain structure. Here we consider theoretically the yields of bimolecular reactions between membrane-localized reactants, when both the reactants and products are confined to the disordered phase. It is shown that compartmentalization of reactants in disconnected domains can lead to significant reductions in reaction yields. The reduction in yield was calculated for classical bimolecular processes and for enzyme-catalyzed reactions. These ideas can be used to explain certain experimental observations.

Biophysical Phenomena↗
PubMed1998

Myoglobin mutants giving the largest geminate yield in CO rebinding in the nanosecond time domain.

We have measured the rebinding of carbon monoxide (CO) to some distal mutants of myoglobin (Mb) in the time range from 10(-8) to 10(-1) s by flash photolysis, in which the photodissociated CO rebinds to the heme iron without escaping to the solvent water from the protein matrix. We have found that the double mutants [His64-->Val/Val68-->Thr (H64V/V68T) and His64-->Val/Val68-->Ser (H64V/V68S)] have an extremely large geminate yield (70-80%) in water at 5 degreesC, in contrast to the 7% of the geminate yield of wild-type Mb. The CO geminate yields for these two mutants are the largest in those of Mb mutants reported so far, showing that the two mutants have a unique heme environment that favors CO geminate rebinding. Comparing the crystal structures and 1H-NMR and vibrational spectral data of H64V/V68T and H64V/V68S with those of other mutants, we discuss factors that may control the nanosecond geminate CO rebinding and CO migration in the protein matrix.

Carbon Monoxide↗
PubMed1980

Dextran alpha-(1 yields 2)-debranching enzyme from Flavobacterium Sp. M-73. Properties and mode of action.

The general properties and specificity of a dextran alpha-(1 yields 2)-debranching enzyme from Flavobacterium have been examined in order to apply this enzyme to the structural analysis of highly branched dextrans. The optimum pH range and temperature were pH 5.5-6.5, and 45 degrees, respectively. The enzyme was stable up to 40 degrees on heating for 10 min, and over a pH range of 6.5-9.0 on incubation at 4 degrees for 24 h. The effects of various metal ions and chemical reagents have also been examined. The debranching enzyme has a strict specificity for the (1 yields 2)-alpha-D-glucosidic linkage at branch points of dextrans and related branched oligosaccharides, and produces D-glucose as the only reducing sugar. The degree of hydrolysis of the dextrans by this enzyme and the Km value (mg/mL) were as follows: B-1298 soluble, 25.2%, 0.21; B-1299 soluble, 31.5%, 0.27; and B-1397, 11.8%, 0.91. the debranching enzyme thus has a novel type of specificity as a dextranhydrolase. We have termed this enzyme as dextran alpha-(1 yields 2)-debranching enzyme, and its systematic name is also discussed.

Cations↗
PubMed2001

Tumour markers in serum, bronchoalveolar lavage and biopsy cytosol in lung carcinoma: what environment lends the optimum diagnostic yield?

BACKGROUND: The aim of this study was to assess the diagnostic yield of the tumour markers carbohydrate antigen (CA 125), carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), squamous cell carcinoma antigen (SCC) and specific tissue polypeptide antigen (TPS) in serum, bronchoalveolar lavage (BAL) and biopsy cytosol in a group of patients with bronchogenic carcinoma. METHODS: Serum, BAL and biopsy cytosol samples were collected in a group of 85 patients with benign or malignant pulmonary diseases. After appropriate processing, tumour markers were determined by enzyme immunoassay. The diagnostic yields (sensitivity, specificity and accuracy) in each environment (serum, BAL or biopsy) were obtained by using "ROC" curves. RESULTS: Determined individually, CA 125, NSE and SCC show the greatest diagnostic accuracy in cytosol. CEA and TPS do so in BAL. CEA is the most relevant marker in serum and BAL, and CA 125 in cytosol. When the different tumour markers are associated, they offer better overall yields for all except TPS. CONCLUSIONS: For the factors evaluated in this study, determination of CEA in BAL was clinically the most useful marker in comparison with serum and cytosol determinations, although the latter may also be helpful in certain situations. Although there is no specific tumour marker for lung cancer, the combination of several can be used to monitor most patients with lung cancer.

Adult↗
PubMed1986

Bethanechol increases the diagnostic yield in patients with esophageal chest pain.

The diagnostic yield of routine esophageal manometrics in evaluating noncardiac chest pain is low. To determine if bethanechol stimulation would increase the diagnostic yield, we examined 87 patients with chest pain but no gastroesophageal reflux, 47 patients with gastroesophageal reflux but no chest pain, and 20 normal subjects. All subjects underwent standard esophageal manometrics before and after two doses of 50 micrograms/kg body wt bethanechol administered subcutaneously 15 min apart. Mean amplitude and duration of contractions and percentage of abnormal contractions were measured in the distal 7 cm of the esophageal body. Pathologic manometric parameters were defined as mean +/- 2 SD of values obtained in normal patients. Patients with chest pain had pathological responses for amplitude of contraction, duration of contraction, and percentage of abnormal contractions of 31%, 14%, and 22%, respectively, in the basal period. This increased to 43%, 66%, and 40%, respectively, after the first dose of bethanechol and to 53%, 85%, and 82% after the second dose of bethanechol. Chest pain was reproduced with new manometric abnormalities in 46% of patients after the first dose of bethanechol and in 77% after the second dose. Our conclusions are that: sequential bethanechol administration significantly increases the diagnostic yield of standard esophageal manometrics in the evaluation of noncardiac chest pain and duration of contraction after pharmacologic provocation with bethanechol is the best parameter to segregate patients with chest pain from normal subjects and gastroesophageal reflux patients.

Adult↗